Richard G. Luthy is the Silas H. Palmer Professor of Civil and Environmental Engineering and Senior Fellow in the Woods Institute for the Environmnet. He is the Director of the NSF Engineering Research Center for Re-inventing the Nation’s Urban Water Infrastructure (ReNUWIt), a four-university consortium that seeks more sustainable solutions to urban water challenges in the arid west.

His area of teaching and research is environmental engineering and water quality with applications to water reuse, stormwater use, and systems-level analysis of our urban water challenges. His research addresses management of persistent organic contaminants and contaminants of emerging concern in natural systems that are engineered to improve water quality and protect the environment and human health.

Professor Luthy is a past chair of the National Research Council's Water Science and Technology Board and a former President of the Association of Environmental Engineering and Science Professors. He is Chair of the NRC's Committee on the Beneficial Use of Stormwater and Graywater. He is a registered professional engineer, a board certified environmental engineer, and a member of the National Academy of Engineering.

Academic Appointments

Honors & Awards

  • Gordon Maskew Fair Award, American Academy of Environmental Engineer & Scientists (2015)
  • Chair, National Research Council Committee on Beneficial Use of Stormwater and Graywater (2013-2015)
  • Fellow, Water Environment Federation (2013)
  • Civil & Environmental Engineering Academy of Distinguished Alumni, University of California, Berkeley (2012)
  • Distinguished Lecturer, AEESP (2011-2012)
  • Einstein Chair Professor, Chinese Academy of Sciences (2005)
  • Chair Professor, Dept. of Environ. Sci. and Eng., Tsinghua University, Beijing, China (2004-2007)

Boards, Advisory Committees, Professional Organizations

  • Member, National Academy of Engineering (1999 - Present)

Professional Education

  • Hon. Sci. D., Clarkson University, Potsdam, NY, Environmental Engineering (2005)
  • Ph.D., University of California, Berkeley, CA, Civil Engineering (Environmental Engineering) (1976)
  • M.S., University of California, Berkeley, CA, Civil Engineering (Environmental Engineering) (1974)
  • M.S., University of Hawaii, Honolulu, HI, Ocean Engineering (1969)
  • B.S., University of California, Berkeley, CA, Chemical Engineering (1967)

2015-16 Courses

Stanford Advisees

All Publications

  • Urban Water-Supply Reinvention DAEDALUS Luthy, R. G., Sedlak, D. L. 2015; 144 (3): 72-82
  • In Situ Sediment Treatment Using Activated Carbon: A Demonstrated Sediment Cleanup Technology INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT Patmont, C. R., Ghosh, U., LaRosa, P., Menzie, C. A., Luthy, R. G., Greenberg, M. S., Cornelissen, G., Eek, E., Collins, J., Hull, J., Hjartland, T., Glaza, E., Bleiler, J., Quadrini, J. 2015; 11 (2): 195-207


    This paper reviews general approaches for applying activated carbon (AC) amendments as an in situ sediment treatment remedy. In situ sediment treatment involves targeted placement of amendments using installation options that fall into two general approaches: 1) directly applying a thin layer of amendments (which potentially incorporates weighting or binding materials) to surface sediment, with or without initial mixing; and 2) incorporating amendments into a premixed, blended cover material of clean sand or sediment, which is also applied to the sediment surface. Over the past decade, pilot- or full-scale field sediment treatment projects using AC-globally recognized as one of the most effective sorbents for organic contaminants-were completed or were underway at more than 25 field sites in the United States, Norway, and the Netherlands. Collectively, these field projects (along with numerous laboratory experiments) have demonstrated the efficacy of AC for in situ treatment in a range of contaminated sediment conditions. Results from experimental studies and field applications indicate that in situ sequestration and immobilization treatment of hydrophobic organic compounds using either installation approach can reduce porewater concentrations and biouptake significantly, often becoming more effective over time due to progressive mass transfer. Certain conditions, such as use in unstable sediment environments, should be taken into account to maximize AC effectiveness over long time periods. In situ treatment is generally less disruptive and less expensive than traditional sediment cleanup technologies such as dredging or isolation capping. Proper site-specific balancing of the potential benefits, risks, ecological effects, and costs of in situ treatment technologies (in this case, AC) relative to other sediment cleanup technologies is important to successful full-scale field application. Extensive experimental studies and field trials have shown that when applied correctly, in situ treatment via contaminant sequestration and immobilization using a sorbent material such as AC has progressed from an innovative sediment remediation approach to a proven, reliable technology. Integr Environ Assess Manag 2015; 11:195-207. © 2014 The Authors. Published 2014 SETAC.

    View details for DOI 10.1002/ieam.1589

    View details for Web of Science ID 000357020200004

    View details for PubMedID 25323491

  • Modeling Uptake of Hydrophobic Organic Contaminants into Polyethylene Passive Samplers ENVIRONMENTAL SCIENCE & TECHNOLOGY Thompson, J. M., Hsieh, C., Luthy, R. G. 2015; 49 (4): 2270-2277


    Single-phase passive samplers are gaining acceptance as a method to measure hydrophobic organic contaminant (HOC) concentration in water. Although the relationship between the HOC concentration in water and passive sampler is linear at equilibrium, mass transfer models are needed for nonequilibrium conditions. We report measurements of organochlorine pesticide diffusion and partition coefficients with respect to polyethylene (PE), and present a Fickian approach to modeling HOC uptake by PE in aqueous systems. The model is an analytic solution to Fick's second law applied through an aqueous diffusive boundary layer and a polyethylene layer. Comparisons of the model with existing methods indicate agreement at appropriate boundary conditions. Laboratory release experiments on the organochlorine pesticides DDT, DDE, DDD, and chlordane in well-mixed slurries support the model's applicability to aqueous systems. In general, the advantage of the model is its application in the cases of well-agitated systems, low values of polyethylene-water partioning coefficients, thick polyethylene relative to the boundary layer thickness, and/or short exposure times. Another significant advantage is the ability to estimate, or at least bound, the needed exposure time to reach a desired CPE without empirical model inputs. A further finding of this work is that polyethylene diffusivity does not vary by transport direction through the sampler thickness.

    View details for DOI 10.1021/es504442s

    View details for Web of Science ID 000349806400037

    View details for PubMedID 25607420

  • Improvement of Urban Lake Water Quality by Removal of Escherichia coli through the Action of the Bivalve Anodonta califomiensis ENVIRONMENTAL SCIENCE & TECHNOLOGY Ismail, N. S., Dodd, H., Sassoubre, L. M., Horne, A. J., Boehm, A. B., Luthy, R. G. 2015; 49 (3): 1664-1672


    High levels of fecal indicator bacteria, such as Escherichia coli, can be indicative of poor water quality. The use of shellfish to reduce eutrophication has been proposed, but application of bivalves to reduce bacterial levels has not been extensively reported. Removal of E. coli by the native freshwater mussel Anodonta californiensis was studied using laboratory batch systems and field-based flow-through systems. Batch systems were utilized to determine the fate and inactivation of E. coli after uptake by the mussel. Batch experiments demonstrated that uptake patterns followed first order kinetics and E. coli was inactivated with less than 5% of the initial colonies recoverable in fecal matter or tissue. Flow-through systems located at an urban impaired lake in San Francisco, CA were utilized to determine uptake kinetics under environmentally relevant conditions. The bivalves maintained a 1-log removal of E. coli for the duration of exposure. The calculated uptake rates can be used in conjunction with hydrologic models to determine the number of bivalves needed to maintain removal of E. coli in different freshwater systems. The outcomes of this study support the use of native freshwater bivalves to achieve the co-benefits of rehabilitating a freshwater ecosystem and improving water quality via reduction of E. coli in contaminated freshwater systems.

    View details for DOI 10.1021/es5033212

    View details for Web of Science ID 000349060300052

    View details for PubMedID 25587628

  • Assessment of the crop coefficient for saltgrass under native riparian field conditions in the desert southwest HYDROLOGICAL PROCESSES Bawazir, A. S., Luthy, R., King, J. P., Tanzy, B. F., Solis, J. 2014; 28 (25): 6163-6171

    View details for DOI 10.1002/hyp.10100

    View details for Web of Science ID 000346337400013

  • Engagement at the Science-Policy Interface ENVIRONMENTAL SCIENCE & TECHNOLOGY Hering, J. G., Dzombak, D. A., Green, S. A., Luthy, R. G., Swackhamer, D. 2014; 48 (19): 11031-11033

    View details for DOI 10.1021/es504225t

    View details for Web of Science ID 000343016600005

  • Uptake of Contaminants of Emerging Concern by the Bivalves Anodonta californiensis and Corbicula fluminea ENVIRONMENTAL SCIENCE & TECHNOLOGY Ismail, N. S., Mueller, C. E., Morgan, R. R., Luthy, R. G. 2014; 48 (16): 9211-9219


    Uptake of seven contaminants regularly detected in surface waters and spanning a range of hydrophobicities (log D(ow) -1 to 5) was studied for two species of freshwater bivalves, the native mussel Anodonta californiensis and the invasive clam Corbicula fluminea. Batch systems were utilized to determine compound partitioning, and flow-through systems, comparable to environmental conditions in effluent dominated surface waters, were used to determine uptake and depuration kinetics. Uptake of compounds was independent of bivalve type. Log bioconcentration factor (BCF) values were correlated with log D(ow) for nonionized compounds with the highest BCF value obtained for triclocarban (TCC). TCC concentrations were reduced in the water column due to bivalve activity. Anionic compounds with low D(ow) values, i.e., clofibric acid and ibuprofen, were not removed from water, while the organic cation propranolol showed biouptake similar to that of TCC. Batch experiments supported compound uptake patterns observed in flow-through experiments. Contaminant removal from water was observed through accumulation in tissue or settling as excreted pseudofeces or feces. The outcomes of this study indicate the potential utility of bivalve augmentation to improve water quality by removing hydrophobic trace organic compounds found in natural systems.

    View details for DOI 10.1021/es5011576

    View details for Web of Science ID 000340701800034

  • In Situ Sequestration of Hydrophobic Organic Contaminants in Sediments under Stagnant Contact with Activated Carbon. 1. Column Studies ENVIRONMENTAL SCIENCE & TECHNOLOGY Choi, Y., Cho, Y., Luthy, R. G. 2014; 48 (3): 1835-1842


    The effectiveness of activated carbon (AC) treatment to sequester hydrophobic organic contaminants in sediments under stagnant contact was comprehensively studied for the first time. Two years of column experiments were conducted to simulate field conditions with two study sediments contaminated with petroleum and polychlorinated biphenyls, respectively, and variations in AC-sediment contact times, initial AC mixing regimes and distribution, AC particle sizes, and pore-water flow. The benefit of AC treatment was gradually enhanced with time toward the end point of the treatment, where sorption equilibrium is established between sediment and AC. After two years of stagnant contact, the contaminant uptake in polyethylene passive samplers embedded in the columns was reduced by 95-99% for polycyclic aromatic hydrocarbons and 93-97% for polychlorinated biphenyls with 5 and 4 wt % AC dose, respectively, when AC was initially applied by mechanical mixing. These results verify that AC treatment can effectively control the availability of hydrophobic organic contaminants under stagnant conditions within a reasonable time frame following an initial distribution of AC into the sediment. The effectiveness of AC treatment was strongly dependent on AC particle size and AC distribution, while the effect of AC initial mixing regimes and pore-water flow was not pronounced.

    View details for DOI 10.1021/es403335g

    View details for Web of Science ID 000331015100059

  • In Situ Sequestration of Hydrophobic Organic Contaminants in Sediments under Stagnant Contact with Activated Carbon. 2. Mass Transfer Modeling ENVIRONMENTAL SCIENCE & TECHNOLOGY Choi, Y., Cho, Y., Werner, D., Luthy, R. G. 2014; 48 (3): 1843-1850


    The validity of a hydrophobic organic contaminant mass transfer model to predict the effectiveness of in situ activated carbon (AC) treatment under stagnant sediment-AC contact is studied for different contaminants and sediments. The modeling results and data from a previous 24-month column experiment of uptake in polyethylene samplers are within a factor of 2 for parent- and alkylated-polycyclic aromatic hydrocarbons in petroleum-impacted sediment and factors of 3-10 for polychlorinated biphenyls. The model successfully reproduces the relative effects of AC-sediment contact time, contaminant properties, AC particle size, AC mixing regime, AC distribution, and hydraulic conditions observed in the sediment column experiments. The model tracks contaminant concentrations in different sediment compartments over time, which provides useful information on the contaminant sequestration by the added AC. Long-term projection of the effectiveness of AC amendment using the model shows that the effects of AC particle size and particle-scale heterogeneity in AC distribution are pronounced within a year or so. However, the effect of those factors becomes less significant after a much longer contact period (on the order of a decade or two), resulting in substantial reduction in pore-water concentrations, for example, greater than 99% for benz[a]anthracene, under various scenarios.

    View details for DOI 10.1021/es404209v

    View details for Web of Science ID 000331015100060

  • Bioturbation Delays Attenuation of DDT by Clean Sediment Cap but Promotes Sequestration by Thin-Layered Activated Carbon ENVIRONMENTAL SCIENCE & TECHNOLOGY Lin, D., Cho, Y., Werner, D., Luthy, R. G. 2014; 48 (2): 1175-1183


    The effects of bioturbation on the performance of attenuation by sediment deposition and activated carbon to reduce risks from DDT-contaminated sediment were assessed for DDT sediment-water flux, biouptake, and passive sampler (PE) uptake in microcosm experiments with a freshwater worm, Lumbriculus variegatus. A thin-layer of clean sediment (0.5 cm) did not reduce the DDT flux when bioturbation was present, while a thin (0.3 cm) AC cap was still capable of reducing the DDT flux by 94%. Bioturbation promoted AC sequestration by reducing the 28-day DDT biouptake (66%) and DDT uptake into PE (>99%) compared to controls. Bioturbation further promoted AC-sediment contact by mixing AC particles into underlying sediment layers, reducing PE uptake (55%) in sediment compared to the AC cap without bioturbation. To account for the observed effects from bioturbation, a mass transfer model together with a biodynamic model were developed to simulate DDT flux and biouptake, respectively, and models confirmed experimental results. Both experimental measurements and modeling predictions imply that thin-layer activated carbon placement on sediment is effective in reducing the risks from contaminated sediments in the presence of bioturbation, while natural attenuation process by clean sediment deposition may be delayed by bioturbation.

    View details for DOI 10.1021/es404108h

    View details for Web of Science ID 000330205000042

  • Recycled water for augmenting urban streams in mediterranean-climate regions: a potential approach for riparian ecosystem enhancement HYDROLOGICAL SCIENCES JOURNAL-JOURNAL DES SCIENCES HYDROLOGIQUES Lawrence, J. E., Pavia, C. P., Kaing, S., Bischel, H. N., Luthy, R. G., Resh, V. H. 2014; 59 (3-4): 488-501
  • Economic and Ecological Costs and Benefits of Streamflow Augmentation Using Recycled Water in a California Coastal Stream ENVIRONMENTAL SCIENCE & TECHNOLOGY Halaburka, B. J., Lawrence, J. E., Bischel, H. N., Hsiao, J., Plumlee, M. H., Resh, V. H., Luthy, R. G. 2013; 47 (19): 10735-10743


    Streamflow augmentation has the potential to become an important application of recycled water in water scarce areas. We assessed the economic and ecological merits of a recycled water project that opted for an inland release of tertiary-treated recycled water in a small stream and wetland compared to an ocean outfall discharge. Costs for the status-quo scenario of discharging secondary-treated effluent to the ocean were compared to those of the implemented scenario of inland streamflow augmentation using recycled water. The benefits of the inland-discharge scenario were greater than the increase in associated costs by US$1.8M, with recreational value and scenic amenity generating the greatest value. We also compared physical habitat quality, water quality, and benthic macroinvertebrate community upstream and downstream of the recycled water discharge to estimate the effect of streamflow augmentation on the ecosystem. The physical-habitat quality was higher downstream of the discharge, although streamflow came in unnatural diurnal pulses. Water quality remained relatively unchanged with respect to dissolved oxygen, pH, and ammonia-nitrogen, although temperatures were elevated. Benthic macroinvertebrates were present in higher abundances, although the diversity was relatively low. A federally listed species, the California red-legged frog (Rana draytonii), was present. Our results may support decision-making for wastewater treatment alternatives and recycled water applications in Mediterranean climates.

    View details for DOI 10.1021/es305011z

    View details for Web of Science ID 000330094900004

  • A Changing Framework for Urban Water Systems ENVIRONMENTAL SCIENCE & TECHNOLOGY Hering, J. G., Waite, T. D., Luthy, R. G., Drewes, J. E., Sedlak, D. L. 2013; 47 (19): 10721-10726


    Urban water infrastructure and the institutions responsible for its management have gradually evolved over the past two centuries. Today, they are under increasing stress as water scarcity and a growing recognition of the importance of factors other than the cost of service provision are forcing a reexamination of long-held ideas. Research and development that supports new technological approaches and more effective management strategies are needed to ensure that the emerging framework for urban water systems will meet future societal needs.

    View details for DOI 10.1021/es4007096

    View details for Web of Science ID 000330094900002

    View details for PubMedID 23650975

  • Renewing Urban Streams with Recycled Water for Streamflow Augmentation: Hydrologic, Water Quality, and Ecosystem Services Management ENVIRONMENTAL ENGINEERING SCIENCE Bischel, H. N., Lawrence, J. E., Halaburka, B. J., Plumlee, M. H., Bawazir, A. S., King, J. P., McCray, J. E., Resh, V. H., Luthy, R. G. 2013; 30 (8): 455-479
  • Hyporheic Zone in Urban Streams: A Review and Opportunities for Enhancing Water Quality and Improving Aquatic Habitat by Active Management ENVIRONMENTAL ENGINEERING SCIENCE Lawrence, J. E., Skold, M. E., Hussain, F. A., Silverman, D. R., Resh, V. H., Sedlak, D. L., Luthy, R. G., McCray, J. E. 2013; 30 (8): 480-501
  • Unit Process Wetlands for Removal of Trace Organic Contaminants and Pathogens from Municipal Wastewater Effluents ENVIRONMENTAL ENGINEERING SCIENCE Jasper, J. T., Nguyen, M. T., Jones, Z. L., Ismail, N. S., Sedlak, D. L., Sharp, J. O., Luthy, R. G., Horne, A. J., Nelson, K. L. 2013; 30 (8): 421-436
  • Polyethylene-Water Partitioning Coefficients for Parent- and Alkylated-Polycyclic Aromatic Hydrocarbons and Polychlorinated Biphenyls ENVIRONMENTAL SCIENCE & TECHNOLOGY Choi, Y., Cho, Y., Luthy, R. G. 2013; 47 (13): 6943-6950


    We report polyethylene (PE)-water partitioning coefficients (K(PE)) for 17 parent-polycyclic aromatic hydrocarbons (PAHs), 22 alkylated-PAHs, 3 perdeuterated parent-PAHs, and 100 polychlorinated biphenyl (PCB) congeners or coeluting congener groups. The K(PE) values for compounds in the same homologue group are within 0.2 log units for alkylated-PAHs but span up to an order of magnitude for PCBs, due to the greater contribution of the position of the substituents (i.e., chlorines for PCBs and alkyl groups for alkylated-PAHs) to the molecular structure. The K(PE) values in deionized water for parent- and alkylated-PAHs show a good correlation with a regression model employing the number of aromatic carbons (C(AR)) and aliphatic carbons (C(AL)) in each compound: log K(PE) = -0.241 + 0.313 C(AR) + 0.461 C(AL). The regression model is useful for the assessment of freely dissolved aqueous concentrations of alkylated-PAHs, which comprise a significant fraction of the total in petroleum-derived PAHs and in some pyrogenic PAH mixtures. For PCBs, experimentally determined octanol-water partitioning coefficients are the best predictor of the K(PE) values among the molecular parameters studied. The effect of salinity up to 20 or 30 parts per thousand is found to be relatively insignificant on K(PE) values for PAHs or PCBs, respectively.

    View details for DOI 10.1021/es304566v

    View details for Web of Science ID 000321521400029

    View details for PubMedID 23488618

  • Measurement and Modeling of Activated Carbon Performance for the Sequestration of Parent- and Alkylated-Polycyclic Aromatic Hydrocarbons in Petroleum-Impacted Sediments ENVIRONMENTAL SCIENCE & TECHNOLOGY Choi, Y., Cho, Y., Gala, W. R., Luthy, R. G. 2013; 47 (2): 1024-1032


    We present a first comprehensive set of experiments that demonstrate the performance of activated carbon (AC) to reduce the availability of polycyclic aromatic hydrocarbons (PAHs) including alkylated-PAHs in petroleum-impacted sediments. The uptake in polyethylene samplers for total PAHs in a well-mixed sediment slurry was reduced up to 99% and 98% for petroleum-impacted sediments with oil contents of 1% and 2%, respectively, by treatment with 5% AC. The AC showed similar efficiency for parent-PAHs and a suite of alkylated-PAHs, which predominate over parent-PAHs in petroleum-impacted sediments. A mass transfer model was used to simulate the AC performance in a slurry phase with site-specific mass transfer parameters determined in this study. Comparison between the experimental data and simulation results suggested that dissolved organic matter and/or oil phase may have attenuated the AC performance by a factor of 5-6 for 75-300 μm AC with 5% dose at one month. The attenuation in AC performance became negligible with increase in AC-sediment slurry contact time to 12 months and with decrease in AC particle size. The results show the potential for AC amendment to sequester PAHs in petroleum-impacted sediments and the effect of contact time and AC particle size on the efficiency of the treatment.

    View details for DOI 10.1021/es303770c

    View details for Web of Science ID 000313667400045

    View details for PubMedID 23240641

  • A Changing Framework for Urban Water Systems Environmental Science & Technology, ASAP Hering, Janet, G., Waite, T., David, Luthy, Richard, G., Drewes, Jorg, E., Sedlak, David, L. 2013

    View details for DOI 10.1021/es4007096

  • Assessment of the crop coefficient for saltgrass under native riparian field conditions in the desert southwest Hydrological Processes Bawazir, A. S., Luthy, R., King, J. P., Tanzy, B. F., Solis, J. 2013

    View details for DOI 10.1002/hyp.10100

  • Economic and Ecological Costs and Benefits of Streamflow Augmentation Using Recycled Water in a California Coastal Stream Environmental Science & Technology Halaburka, Brian, J., Lawrence, Justin, E., Bischel, Heather, N., Hsiao, J., Plumlee, Megan, H., Resh, Vincent, H., Luthy, Richard, G. 2013

    View details for DOI 10.1021/es305011z

  • Hyporheic zone in urban streams: A review and opportunities for enhancing water quality and improving aquatic habitat by active management Environmental Engineering Science Lawrence, J. E., Skold, M. E., Hussain, F. A., Silverman, D. R., Resh, V. H., Sedlak, D. L., Luthy, Richard, G. 2013; 8 (30): 480-501

    View details for DOI 10.1089/ees.2012.0235

  • Introduction: Reinventing Urban Water Infrastructure Environmental Engineering Science Sedlak, D. L., Drewes, J. E., Luthy, R. G. 2013; 30 (8): 393-394

    View details for DOI 10.1089/ees.2013.3008

  • Design Options for a More Sustainable Urban Water Environment Environmental Science & Technology Luthy, R. G. 2013; 47 (19): 10719-10720

    View details for DOI 10.1021/es403728p

  • Kinetics and pathways for the debromination of polybrominated diphenyl ethers by bimetallic and nanoscale zerovalent iron: Effects of particle properties and catalyst CHEMOSPHERE Zhuang, Y., Jin, L., Luthy, R. G. 2012; 89 (4): 426-432


    Polybrominated diphenyl ethers (PBDEs) are recognized as a new class of widely-distributed and persistent contaminants for which effective treatment and remediation technologies are needed. In this study, two kinds of commercially available nanoscale Fe(0) slurries (Nanofer N25 and N25S), a freeze-dried laboratory-synthesized Fe(0) nanoparticle (nZVI), and their palladized forms were used to investigate the effect of particle properties and catalyst on PBDE debromination kinetics and pathways. Nanofers and their palladized forms were found to debrominate PBDEs effectively. The laboratory-synthesized Fe(0) nanoparticles also debrominated PBDEs, but were slower due to deactivation by the freeze-drying and stabilization processes in the laboratory synthesis. An organic modifier, polyacrylic acid (PAA), bound on N25S slowed PBDE debromination by a factor of three to four compared to N25. The activity of palladized nZVI (nZVI/Pd) was optimized at 0.3 Pd/Fe wt% in our system. N25 could debrominate selected environmentally-abundant PBDEs, including BDE 209, 183, 153, 99, and 47, to end products di-BDEs, mono-BDEs and diphenyl ether (DE) in one week, while nZVI/Pd (0.3 Pd/Fe wt%) mainly resulted in DE as a final product. Step-wise major PBDE debromination pathways by unamended and palladized Fe(0) are described and compared. Surface precursor complex formation is an important limiting factor for palladized Fe(0) reduction as demonstrated by PBDE pathways where steric hindrance and rapid sequential debromination of adjacent bromines play an important role.

    View details for DOI 10.1016/j.chemosphere.2012.05.078

    View details for Web of Science ID 000307626000011

    View details for PubMedID 22732301

  • Assessment of Nontoxic, Secondary Effects of Sorbent Amendment to Sediments on the Deposit-Feeding Organism Neanthes arenaceodentata ENVIRONMENTAL SCIENCE & TECHNOLOGY Janssen, E. M., Choi, Y., Luthy, R. G. 2012; 46 (7): 4134-4141


    Activated carbon (AC) amendments to sediments were tested for nontoxic, secondary effects on survival, weight change, and energetic biomarkers of the deposit feeder Neanthes arenaceodentata. The tests employed silica sand, reference sediments, and contaminated sediments. Survival was not affected by the sediment type, the AC dose (20% versus 5%), or the AC particle size. Without additional food supply, exposure to untreated and AC-amended sediments resulted in similar reduction of weight and lipid content, with no difference between ingestible and noningestible AC. Overall, whether with or without AC, the organisms showed signs of starvation, as the organisms would most likely rely on organic surface deposits for their diet in the environments from which the sediments were collected. When additional food was supplied, the organisms grew significantly and maintained higher lipid and glycogen contents. However, when feeding on fish food, organisms grew less in AC amendments with slightly lower lipid and glycogen contents relative to organisms exposed to untreated sediment. Batch tests show that AC did not sorb sediment-associated nitrogen but sorbed nitrogen from fish food. Despite some effects of AC on these deposit feeders, absolute effects of AC amendments on growth and energy reserves were not significant.

    View details for DOI 10.1021/es204066g

    View details for Web of Science ID 000302850400070

    View details for PubMedID 22372688

  • Long-term monitoring and modeling of the mass transfer of polychlorinated biphenyls in sediment following pilot-scale in-situ amendment with activated carbon. Journal of contaminant hydrology Cho, Y., Werner, D., Choi, Y., Luthy, R. G. 2012; 129-130: 25-37


    The results of five years of post-treatment monitoring following in-situ activated carbon (AC) placement for stabilization of polychlorinated biphenyls (PCBs) at an inter-tidal mudflat adjacent to Hunters Point Shipyard, San Francisco Bay, CA, USA are reported in this paper. After five years, AC levels of the sediment cores were comparable to those at earlier sampling times. Passive sampler uptake validated the benefit of the AC amendment with a strong local sorbent dose-response relationship. The PCB uptakes in passive samplers decreased up to 73% with a 3.7 dry wt.% AC dose after five years, confirming the temporal enhancement of the amendment benefit from a 19% reduction with a 4.4% dose observed within one month. The long-term effectiveness of AC, the local AC dose response, the impact of fouling by NOM, the spatial heterogeneity of AC incorporation, and the effects of advective sediment pore-water movement are discussed with the aid of a PCB mass transfer model. Modeling and experimental results indicated that the homogeneous incorporation of AC in the sediment will significantly accelerate the benefit of the treatment.

    View details for DOI 10.1016/j.jconhyd.2011.09.009

    View details for PubMedID 22055155

  • Intra-particle migration of mercury in granular polysulfide-rubber-coated activated carbon (PSR-AC) CHEMOSPHERE Kim, E., Masue-Slowey, Y., Fendorf, S., Luthy, R. G. 2012; 86 (6): 648-654


    The depth profile of mercuric ion after the reaction with polysulfide-rubber-coated activated carbon (PSR-AC) was investigated using micro-X-ray fluorescence (?-XRF) imaging techniques and mathematical modeling. The ?-XRF results revealed that mercury was concentrated at 0-100 ?m from the exterior of the particle after 3 months of treatment with PSR-AC in 10 ppm HgCl(2) aqueous solution. The ?-X-ray absorption near edge spectroscopic (?-XANES) analyses indicated HgS as a major mercury species, and suggested that the intra-particle mercury transport involved a chemical reaction with PSR polymer. An intra-particle mass transfer model was developed based on either a Langmuir sorption isotherm with liquid phase diffusion (Langmuir model) or a kinetic sorption with surface diffusion (kinetic sorption model). The Langmuir model predicted the general trend of mercury diffusion, although at a slower rate than observed from the ?-XRF map. A kinetic sorption model suggested faster mercury transport, which overestimated the movement of mercuric ions through an exchange reaction between the fast and slow reaction sites. Both ?-XRF and mathematical modeling results suggest mercury removal occurs not only at the outer surface of the PSR-AC particle but also at some interior regions due to a large PSR surface area within an AC particle.

    View details for DOI 10.1016/j.chemosphere.2011.11.012

    View details for Web of Science ID 000301096200014

    View details for PubMedID 22133913

  • Sorption of Organic Compounds to Fresh and Field-Aged Activated Carbons in Soils and Sediments ENVIRONMENTAL SCIENCE & TECHNOLOGY Oen, A. M., Beckingham, B., Ghosh, U., Krusa, M. E., Luthy, R. G., Hartnik, T., Henriksen, T., Cornelissen, G. 2012; 46 (2): 810-817


    Activated carbon (AC) amendment to polluted sediment or soil is an emerging in situ treatment technique that reduces freely dissolved porewater concentrations and subsequently reduces the ecological and human health risk of hydrophobic organic compounds (HOCs). An important question is the capacity of the amended AC after prolonged exposure in the field. To address this issue, sorption of freshly spiked and native HOCs to AC aged under natural field conditions and fresh AC amendments was compared for one soil and two sediments. After 12-32 months of field aging, all AC amendments demonstrated effectiveness for reducing pore water concentrations of both native (30-95%) and spiked (10-90%) HOCs compared to unamended sediment or soil. Values of K(AC) for field-aged AC were lower than freshly added AC for spiked HOCs up to a factor of 10, while the effect was less for native HOCs. The different behavior in sorbing native HOCs compared to freshly spiked HOCs was attributed to differences in the sorption kinetics and degree of competition for sorption sites between the contaminants and pore-clogging natural organic matter. The implications of these findings are that amended AC can still be effective in sorbing additional HOCs some years following amendment in the field. Thus, a certain level of long-term sustainability of this remediation approach is observed, but conclusions for decade-long periods cannot be drawn solely based on the present study.

    View details for DOI 10.1021/es202814e

    View details for Web of Science ID 000299136200033

    View details for PubMedID 22128748

  • Management Experiences and Trends for Water Reuse Implementation in Northern California ENVIRONMENTAL SCIENCE & TECHNOLOGY Bischel, H. N., Simon, G. L., Frisby, T. M., Luthy, R. G. 2012; 46 (1): 180-188


    In 2010, California fell nearly 300,000 acre-ft per year (AFY) short of its goal to recycle 1,000,000 AFY of municipal wastewater. Growth of recycled water in the 48 Northern California counties represented only 20% of the statewide increase in reuse between 2001 and 2009. To evaluate these trends and experiences, major drivers and challenges that influenced the implementation of recycled water programs in Northern California are presented based on a survey of 71 program managers conducted in 2010. Regulatory requirements limiting discharge, cited by 65% of respondents as a driver for program implementation, historically played an important role in motivating many water reuse programs in the region. More recently, pressures from limited water supplies and needs for system reliability are prevalent drivers. Almost half of respondents (49%) cited ecological protection or enhancement goals as drivers for implementation. However, water reuse for direct benefit of natural systems and wildlife habitat represents just 6-7% of total recycling in Northern California and few financial incentives exist for such projects. Economic challenges are the greatest barrier to successful project implementation. In particular, high costs of distribution systems (pipelines) are especially challenging, with $1 to 3 million/mile costs experienced. Negative perceptions of water reuse were cited by only 26% of respondents as major hindrances to implementation of surveyed programs.

    View details for DOI 10.1021/es202725e

    View details for Web of Science ID 000298762900026

    View details for PubMedID 22107126



    Interactions of perfluoroalkyl acids (PFAAs) with tissue and serum proteins likely contribute to their tissue distribution and bioaccumulation patterns. Protein-water distribution coefficients (K(PW) ) based on ligand associations with bovine serum albumin (BSA) as a model protein were recently proposed as biologically relevant parameters to describe the environmental behavior of PFAAs, yet empirical data on such protein binding behavior are limited. In the present study, associations of perfluoroalkyl carboxylates (PFCAs) with two to 12 carbons (C?-C??) and perfluoroalkyl sulfonates with four to eight carbons (C?, C?, and C?) with BSA are evaluated at low PFAA:albumin mole ratios and various solution conditions using equilibrium dialysis, nanoelectrospray ionization mass spectrometry, and fluorescence spectroscopy. Log K(PW) values for C? to C?? PFAAs range from 3.3 to 4.3. Affinity for BSA increases with PFAA hydrophobicity but decreases from the C? to C?? PFCAs, likely due to steric hindrances associated with longer and more rigid perfluoroalkyl chains. The C?-sulfonate exhibits increased affinity relative to the equivalent chain-length PFCA. Fluorescence titrations support evidence that an observed dependence of PFAA-BSA binding on pH is attributable to conformational changes in the protein. Association constants determined for perfluorobutanesulfonate and perfluoropentanoate with BSA are on the order of those for long-chain PFAAs (K(a) ?10?/M), suggesting that physiological implications of strong binding to albumin may be important for short-chain PFAAs.

    View details for DOI 10.1002/etc.647

    View details for Web of Science ID 000296230300005

    View details for PubMedID 21842491

  • Partitioning of dissolved organic matter-bound mercury between a hydrophobic surface and polysulfide-rubber polymer WATER RESEARCH Kim, E., Luthy, R. G. 2011; 45 (17): 5441-5448


    This study investigated the role of dissolved organic matter on mercury partitioning between a hydrophobic surface (polyethylene, PE) and a reduced sulfur-rich surface (polysulfide rubber, PSR). Comparative sorption studies employed polyethylene and polyethylene coated with PSR for reactions with DOM-bound mercuric ions. These studies revealed that PSR enhanced the Hg-DOM removal from water when DOM was Suwannee River natural organic matter (NOM), fulvic acid (FA), or humic acid (HA), while the same amount of 1,3-propanedithiol-bound mercuric ion was removed by both PE and PSR-PE. The differences for Hg-DOM removal efficiencies between PE and PSR-PE varied depending on which DOM was bound to mercuric ion as suggested by the PE/water and PSR-PE/water partition coefficients for mercury. The surface concentrations of mercury on PE and PSR-PE with the same DOM measured by x-ray photoelectron spectroscopy were similar, which indicated the comparable amounts of immobilized mercury on PE and PSR-PE being exposed to the aqueous phase. With these observations, two major pathways for the immobilization reactions between PSR-PE and Hg-DOM were examined: 1) adsorption of Hg-DOM on PE by hydrophobic interactions between DOM and PE, and 2) addition reaction of Hg-DOM onto PSR by a complexation reaction between Hg and PSR. The percent contribution of each pathway was derived from a mass balance and the ratios among aqueous mercury, PE-bound Hg-DOM, and PSR-bound Hg-DOM concentrations. The results indicate strong binding of mercuric ion with both dissolved organic matter and PSR polymer. The FT-IR examination of Hg-preloaded-PSR-PEs after the reaction with DOM corroborated a strong interaction between mercuric ion and 1,3-propanedithiol compared to Hg-HA, Hg-FA, or Hg-NOM interactions.

    View details for DOI 10.1016/j.watres.2011.08.003

    View details for Web of Science ID 000295894600010

    View details for PubMedID 21872900

  • Reactive transport of neutral mercury species in polysulfide-rubber-coated activated carbon (PSR-AC) particle Kim, E., Masue-Slowey, Y., Fendorf, S., Luthy, R. G. AMER CHEMICAL SOC. 2011


    The benthic community was analyzed to evaluate pollution-induced changes for the polychlorinated biphenyl (PCB)-contaminated site at Hunters Point (HP) relative to 30 reference sites in San Francisco Bay, California, USA. An analysis based on functional traits of feeding, reproduction, and position in the sediment shows that HP is depauperate in deposit feeders, subsurface carnivores, and species with no protective barrier. Sediment chemistry analysis shows that PCBs are the major risk drivers at HP (1,570 ppb) and that the reference sites contain very low levels of PCB contamination (9 ppb). Different feeding traits support the existence of direct pathways of exposure, which can be mechanistically linked to PCB bioaccumulation by biodynamic modeling. The model shows that the deposit feeder Neanthes arenaceodentata accumulates approximately 20 times more PCBs in its lipids than the facultative deposit feeder Macoma balthica and up to 130 times more than the filter feeder Mytilus edulis. The comparison of different exposure scenarios suggests that PCB tissue concentrations at HP are two orders of magnitude higher than at the reference sites. At full scale, in situ sorbent amendment with activated carbon may reduce PCB bioaccumulation at HP by up to 85 to 90% under favorable field and treatment conditions. The modeling framework further demonstrates that such expected remedial success corresponds to exposure conditions suggested as the cleanup goal for HP. However, concentrations remain slightly higher than at the reference sites. The present study demonstrates how the remedial success of a sorbent amendment, which lowers the PCB availability, can be compared to reference conditions and traditional cleanup goals, which are commonly based on bulk sediment concentrations.

    View details for DOI 10.1002/etc.574

    View details for Web of Science ID 000293060900011

    View details for PubMedID 21560148

  • Dehalogenation of Polybrominated Diphenyl Ethers and Polychlorinated Biphenyl by Bimetallic, Impregnated, and Nanoscale Zerovalent Iron ENVIRONMENTAL SCIENCE & TECHNOLOGY Zhuang, Y., Ahn, S., Seyfferth, A. L., Masue-Slowey, Y., Fendorf, S., Luthy, R. G. 2011; 45 (11): 4896-4903


    Nanoscale zerovalent iron particles (nZVI), bimetallic nanoparticles (nZVI/Pd), and nZVI/Pd impregnated activated carbon (nZVI/Pd-AC) composite particles were synthesized and investigated for their effectiveness to remove polybrominated diphenyl ethers (PBDEs) and/or polychlorinated biphenyls (PCBs). Palladization of nZVI promoted the dehalogenation kinetics for mono- to tri-BDEs and 2,3,4-trichlorobiphenyl (PCB 21). Compared to nZVI, the iron-normalized rate constants for nZVI/Pd were about 2-, 3-, and 4-orders of magnitude greater for tri-, di-, and mono-BDEs, respectively, with diphenyl ether as a main reaction product. The reaction kinetics and pathways suggest an H-atom transfer mechanism. The reaction pathways with nZVI/Pd favor preferential removal of para-halogens on PBDEs and PCBs. X-ray fluorescence mapping of nZVI/Pd-AC showed that Pd mainly deposits on the outer part of particles, while Fe was present throughout the activated carbon particles. While BDE 21 was sorbed onto activated carbon composites quickly, debromination was slower compared to reaction with freely dispersed nZVI/Pd. Our XPS and chemical data suggest about 7% of the total iron within the activated carbon was zerovalent, which shows the difficulty with in-situ synthesis of a significant fraction of zerovalent iron in the microporous material. Related factors that likely hinder the reaction with nZVI/Pd-AC are the heterogeneous distribution of nZVI and Pd on activated carbon and/or immobilization of hydrophobic organic contaminants at the adsorption sites thereby inhibiting contact with nZVI.

    View details for DOI 10.1021/es104312h

    View details for Web of Science ID 000291128700035

    View details for PubMedID 21557574

  • Saving water CHEMISTRY WORLD Smith, M., Luthy, R. 2011; 8 (6): 29-29
  • In Situ Measurement of PCB Pore Water Concentration Profiles in Activated Carbon-Amended Sediment Using Passive Samplers ENVIRONMENTAL SCIENCE & TECHNOLOGY Oen, A. M., Janssen, E. M., Cornelissen, G., Breedveld, G. D., Eek, E., Luthy, R. G. 2011; 45 (9): 4053-4059


    Vertical pore water profiles of in situ PCBs were determined in a contaminated mudflat in San Francisco Bay, CA, 30 months after treatment using an activated carbon amendment in the upper layer of the sediment. Pore water concentrations were derived from concentrations of PCBs measured in two passive samplers; polyethylene (PE, 51 ?m thick) and polyoxymethylene (POM, 17 ?m thick) at different sediment depths. To calculate pore water concentrations from PCB contents in the passive samplers, an equilibrium approach and a first-order uptake model were applied, using five performance reference compounds to estimate pore water sampling rates. Vertical pore water profiles showed good agreement among the measurement and calculation methods with variations within a factor of 2, which seems reasonable for in situ measurements. The close agreements of pore water estimates for the two sampler materials (PE and POM) and the two methods used to translate uptake in samplers to pore water concentrations demonstrate the robustness and suitability of the passive sampling approach. The application of passive samplers in the sediment presents a promising method for site monitoring and remedial treatment evaluation of sorbent amendment or capping techniques that result in changes of pore water concentrations in the sediment subsurface.

    View details for DOI 10.1021/es200174v

    View details for Web of Science ID 000289819400038

    View details for PubMedID 21473574

  • Drivers and challenges for nonpotable water reuse implementation and the emerging role of trace constituents Luthy, R. G., Bischel, H. N., Simon, G., Frisby, T. M. AMER CHEMICAL SOC. 2011
  • In-situ Sorbent Amendments: A New Direction in Contaminated Sediment Management ENVIRONMENTAL SCIENCE & TECHNOLOGY Ghosh, U., Luthy, R. G., Cornelissen, G., Werner, D., Menzie, C. A. 2011; 45 (4): 1163-1168

    View details for DOI 10.1021/es102694h

    View details for Web of Science ID 000287122400003

    View details for PubMedID 21247210

  • Immobilization of Hg(II) in water with polysulfide-rubber (PSR) polymer-coated activated carbon WATER RESEARCH Kim, E., Seyfferth, A. L., Fendorf, S., Luthy, R. G. 2011; 45 (2): 453-460


    An effective mercury removal method using polymer-coated activated carbon was studied for possible use in water treatment. In order to increase the affinity of activated carbon for mercury, a sulfur-rich compound, polysulfide-rubber (PSR) polymer, was effectively coated onto the activated carbon. The polymer was synthesized by condensation polymerization between sodium tetrasulfide and 1,2-dichloroethane in water. PSR-mercury interactions and Hg-S bonding were elucidated from x-ray photoelectron spectroscopy, and Fourier transform infra-red spectroscopy analyses. The sulfur loading levels were controlled by the polymer dose during the coating process and the total surface area of the activated carbon was maintained for the sulfur loading less than 2 wt%. Sorption kinetic studies showed that PSR-coated activated carbon facilitates fast reaction by providing a greater reactive surface area than PSR alone. High sulfur loading on activated carbon enhanced mercury adsorption contributing to a three orders of magnitude reduction in mercury concentration. ?-X-ray absorption near edge spectroscopic analyses of the mercury bound to activated carbon and to PSR on activated carbon suggests the chemical bond with mercury on the surface is a combination of Hg-Cl and Hg-S interaction. The pH effect on mercury removal and adsorption isotherm results indicate competition between protons and mercury for binding to sulfur at low pH.

    View details for DOI 10.1016/j.watres.2010.08.045

    View details for Web of Science ID 000286790500005

    View details for PubMedID 20965542



    Field-related influences on polychlorinated biphenyl (PCB) exposure were evaluated by employing caged deposit-feeders, Neanthes arenaceodentata, along with polyoxymethylene (POM) samplers using parallel in situ and ex situ bioassays with homogenized untreated or activated carbon (AC) amended sediment. The AC amendment achieved a remedial efficiency in reducing bioaccumulation by 90% in the laboratory and by 44% in the field transplants. In situ measurements showed that PCB uptake by POM samplers was greater for POM placed in the surface sediment compared with the underlying AC amendment, suggesting that tidal exchange of surrounding material with similar PCB availability as untreated sediment was redeposited in the cages. Polychlorinated biphenyls bioaccumulation with caged polychaetes from untreated sediment was half as large under field conditions compared with laboratory conditions. A biodynamic model was used to confirm and quantify the different processes that could have influenced these results. Three factors appeared most influential in the bioassays: AC amendment significantly reduces bioavailability under laboratory and field conditions; sediment deposition within test cages in the field partially masks the remedial benefit of underlying AC-amended sediment; and deposit-feeders exhibit less PCB uptake from untreated sediment when feeding is reduced. Ex situ and in situ experiments inevitably show some differences that are associated with measurement methods and effects of the environment. Parallel ex situ and in situ bioassays, passive sampler measurements, and quantifying important processes with a model can tease apart these field influences.

    View details for Web of Science ID 000285814200017

    View details for PubMedID 20872900

  • Toward Identifying the Next Generation of Superfund and Hazardous Waste Site Contaminants ENVIRONMENTAL HEALTH PERSPECTIVES Ela, W. P., Sedlak, D. L., Barlaz, M. A., Henry, H. F., Muir, D. C., Swackhamer, D. L., Weber, E. J., Arnold, R. G., Ferguson, P. L., Field, J. A., Furlong, E. T., Giesy, J. P., Halden, R. U., Henry, T., Hites, R. A., Hornbuckle, K. C., Howard, P. H., Luthy, R. G., Meyer, A. K., Saez, A. E., vom Saal, F. S., Vulpe, C. D., Wiesner, M. R. 2011; 119 (1): 6-10


    This commentary evolved from a workshop sponsored by the National Institute of Environmental Health Sciences titled "Superfund Contaminants: The Next Generation" held in Tucson, Arizona, in August 2009. All the authors were workshop participants.Our aim was to initiate a dynamic, adaptable process for identifying contaminants of emerging concern (CECs) that are likely to be found in future hazardous waste sites, and to identify the gaps in primary research that cause uncertainty in determining future hazardous waste site contaminants.Superfund-relevant CECs can be characterized by specific attributes: They are persistent, bioaccumulative, toxic, occur in large quantities, and have localized accumulation with a likelihood of exposure. Although still under development and incompletely applied, methods to quantify these attributes can assist in winnowing down the list of candidates from the universe of potential CECs. Unfortunately, significant research gaps exist in detection and quantification, environmental fate and transport, health and risk assessment, and site exploration and remediation for CECs. Addressing these gaps is prerequisite to a preventive approach to generating and managing hazardous waste sites.A need exists for a carefully considered and orchestrated expansion of programmatic and research efforts to identify, evaluate, and manage CECs of hazardous waste site relevance, including developing an evolving list of priority CECs, intensifying the identification and monitoring of likely sites of present or future accumulation of CECs, and implementing efforts that focus on a holistic approach to prevention.

    View details for DOI 10.1289/ehp.1002497

    View details for Web of Science ID 000285788900017

    View details for PubMedID 21205582

  • Debromination of Polybrominated Diphenyl Ethers by Nanoscale Zerovalent Iron: Pathways, Kinetics, and Reactivity ENVIRONMENTAL SCIENCE & TECHNOLOGY Zhuang, Y., Ahn, S., Luthy, R. G. 2010; 44 (21): 8236-8242


    The debromination of selected polybrominated diphenyl ethers (PBDEs) by nanoscale zerovalent iron particles (nZVI) was studied to investigate the degradation pathways and the reaction kinetics of the PBDEs. The primary PBDE investigated was 2,3,4-tribromodiphenyl ether (BDE 21) to assess degradation pathways. nZVI could effectively debrominate the selected PBDEs into lower brominated compounds and diphenyl ether, a completely debrominated form of PBDEs. The susceptibility of the meta-bromine by nZVI was observed from the debromination tests for PBDEs with single-flanked (2,3-diBDE and 3,4-diBDE) and unflanked (three mono-BDEs) bromines. The stepwise debromination from n-bromo- to (n-1)-bromodiphenyl ether was observed as the dominant reaction process, although simultaneous multistep debromination seemed to be plausible for di-BDEs having two bromines adjacent on the same phenyl ring. The reaction rate constants were estimated by assuming the reaction between PBDEs and nZVI was a pseudo-first-order reaction and the rates decreased with fewer bromine substituents. The reaction rate constants were correlated with the heat of formation and the energy of the lowest unoccupied molecular orbital of the corresponding compounds, and these appear to be useful descriptors of relative reaction rates among PBDE homologue groups.

    View details for DOI 10.1021/es101601s

    View details for Web of Science ID 000283484000044

    View details for PubMedID 20923154

  • Simultaneous removal of mercury(II) and PCBs by polysulfide-rubber(PSR)-coated activated carbon Kim, E., Luthy, R. G. AMER CHEMICAL SOC. 2010
  • Assessment of Advective Porewater Movement Affecting Mass Transfer of Hydrophobic Organic Contaminants in Marine Intertidal Sediment ENVIRONMENTAL SCIENCE & TECHNOLOGY Cho, Y., Werner, D., Moffett, K. B., Luthy, R. G. 2010; 44 (15): 5842-5848


    Advective porewater movement and molecular diffusion are important factors affecting the mass transfer of hydrophobic organic compounds (HOCs) in marsh and mudflat sediments. This study assessed porewater movement in an intertidal mudflat in South Basin adjacent to Hunters Point Shipyard, San Francisco, CA, where a pilot-scale test of sorbent amendment assessed the in situ stabilization of polychlorinated biphenyls (PCBs). To quantify advective porewater movement within the top 0-60 cm sediment layer, we used temperature as a tracer and conducted heat transport analysis using 14-day data from multidepth sediment temperature logging stations and one-dimensional heat transport simulations. The best-fit conditions gave an average Darcy velocity of 3.8cm/d in the downward vertical direction for sorbent-amended sediment with a plausible range of 0 cm/d to 8 cm/d. In a limiting case with no net advection, the best-fit depth-averaged mechanical dispersion coefficient was 2.2x10(-7) m2/s with a range of 0.9x10(-7) m2/s to 5.6x10(-7) m2/s. The Peclet number for PCB mobilization showed that molecular diffusion would control PCB mass transfer from sediment to sorbent particles for the case of uniform distribution of sorbent. However, the advective flow and mechanical dispersion in the test site would significantly benefit the stabilization effect of heterogeneously distributed sorbent by acting to smooth out the heterogeneities and homogenizing pollutant concentrations across the entire bioactive zone. These measurements and modeling techniques on intertidal sediment porewater transport could be useful for the development of more reliable mass transfer models for the prediction of contaminant release within the sediment bed, the movement of HOCs in the intertidal aquatic environment, and in situ sequestration by sorbent addition.

    View details for DOI 10.1021/es903583y

    View details for Web of Science ID 000280367200031

    View details for PubMedID 20608739

  • Noncovalent Interactions of Long-Chain Perfluoroalkyl Acids with Serum Albumin ENVIRONMENTAL SCIENCE & TECHNOLOGY Bischel, H. N., Macmanus-Spencer, L. A., Luthy, R. G. 2010; 44 (13): 5263-5269


    Preferential distribution of long-chain perfluoroalkyl acids (PFAAs) in the liver, kidney, and blood of organisms highlights the importance of PFAA-protein interactions in PFAA tissue distribution patterns. A serum protein association constant may be a useful parameter to characterize the bioaccumulative potential and in vivo bioavailability of PFAAs. In this work, association constants (K(a)) and binding stoichiometries for PFAA-albumin complexes are quantified over a wide range of PFAA:albumin mole ratios. Primary association constants for perfluorooctanoate (PFOA) or perfluorononanoate (PFNA) with the model protein bovine serum albumin (BSA) determined via equilibrium dialysis are on the order of 10(6) M(-1) with one to three primary binding sites. PFNA was greater than 99.9% bound to BSA or human serum albumin (HSA) at a physiological PFAA:albumin mole ratio (<10(-3)), corresponding to a high protein-water distribution coefficient (log K(PW) > 4). Nanoelectrospray ionization mass spectrometry (nanoESI-MS) data reveal PFAA-BSA complexes with up to eight occupied binding sites at a 4:1 PFAA:albumin mole ratio. Association constants estimated by nanoESI-MS are on the order of 10(5) M(-1) for PFOA and PFNA and 10(4) M(-1) for perfluorodecanoate and perfluorooctanesulfonate. The results reported here suggest binding through specific high affinity interactions at low PFAA:albumin mole ratios.

    View details for DOI 10.1021/es101334s

    View details for Web of Science ID 000279304700070

    View details for PubMedID 20540534

  • Polychlorinated Biphenyl Sorption and Availability in Field-Contaminated Sediments ENVIRONMENTAL SCIENCE & TECHNOLOGY Werner, D., Hale, S. E., Ghosh, U., Luthy, R. G. 2010; 44 (8): 2809-2815


    Traditional and new relationships of polychlorinated biphenyl (PCB) distribution among the solid phases, the free aqueous phase, and biolipids are comprehensively reviewed using seven well-characterized freshwater and marine sediments polluted with PCBs. The traditional relationship relating free aqueous concentration and biolipid concentration to sediment total organic carbon, compound octanol-water partitioning coefficient, and solid-phase contaminant concentration overestimates measured free aqueous concentrations and biolipid concentrations by mean factors of 8 and 33, respectively. By contrast, relationships based on measured free aqueous phase concentrations or the PCB mass fraction desorbed from sediment provide reasonable predictions of biolipid concentrations. Solid-phase concentration-based predictions perform better when sorption to amorphous organic matter and black carbon (BC) is distinguished. Contrary to previously published relationships, BC sorption appears to be linear for free aqueous PCB-congener concentrations in the picogram to microgram per liter range.

    View details for DOI 10.1021/es902325t

    View details for Web of Science ID 000276556000013

    View details for PubMedID 19961220

  • Measurement and Modeling of Polychlorinated Biphenyl Bioaccumulation from Sediment for the Marine Polychaete Neanthes arenaceodentata and Response to Sorbent Amendment ENVIRONMENTAL SCIENCE & TECHNOLOGY Janssen, E. M., Croteau, M., Luoma, S. N., Luthy, R. G. 2010; 44 (8): 2857-2863


    Bioaccumulation rates of polychlorinated biphenyls (PCBs) for the marine polychaete Neanthes arenaceodentata were characterized, including PCB uptake rates from water and sediment, and the effect of sorbent amendment to the sediment on PCB bioavailability, organism growth, and lipid content. Physiological parameters were incorporated into a biodynamic model to predict contaminant uptake. The results indicate rapid PCB uptake from contaminated sediment and significant organism growth dilution during time-series exposure studies. PCB uptake from the aqueous phase accounted for less than 3% of the total uptake for this deposit-feeder. Proportional increase of gut residence time and assimilation efficiency as a consequence of the organism's growth was assessed by PCB uptake and a reactor theory model of gut architecture. Pulse-chase feeding and multilabeled stable isotope tracing techniques proved high sediment ingestion rates (i.e., 6-10 times of dry body weight per day) indicating that such deposit-feeders are promising biological indicators for sediment risk assessment. Activated carbon amendment reduced PCB uptake by 95% in laboratory experiments with no observed adverse growth effects on the marine polychaete. Biodynamic modeling explained the observed PCB body burdens for N. arenaceodentata, with and without sorbent amendment.

    View details for DOI 10.1021/es901632e

    View details for Web of Science ID 000276556000020

    View details for PubMedID 20384377

  • Debromination of polybrominated diphenyl ethers by nano-iron particles and carbon-supported nano-iron particles Zhuang, Y., Ahn, S., Luthy, R. G. AMER CHEMICAL SOC. 2010
  • Binding of Perfluorocarboxylates to Serum Albumin: A Comparison of Analytical Methods ANALYTICAL CHEMISTRY MacManus-Spencer, L. A., Tse, M. L., Hebert, P. C., Bischel, H. N., Luthy, R. G. 2010; 82 (3): 974-981


    Perfluorochemicals are globally pervasive contaminants that are persistent, bioaccumulative, and toxic. Perfluorocarboxylic acids (PFCAs) with 8-13 carbons accumulate in the liver and blood of aquatic organisms; PFCA-protein interactions may explain this accumulation pattern. Here, the interactions between PFCAs with 8-11 carbons and serum albumin are examined using three experimental approaches: surface tension titrations, (19)F NMR spectroscopy, and fluorescence spectroscopy. Surface tension titrations indicate complex formation at high (mM) PFCA concentrations. Secondary association constants ranging from 10(2) to 10(4) M(-1) were determined from (19)F NMR titrations at high PFCA:albumin mole ratios. Fluorescence measurements indicate that PFCA-albumin interactions alter the protein conformation at low PFCA:albumin mole ratios (up to 5:1) and suggest two binding classes with association constants around 10(5) and 10(2) M(-1). While (19)F NMR and fluorescence provide both qualitative and quantitative information about PFCA-albumin interactions, surface tension provides only qualitative information. Limitations associated with instrumentation and methods require high PFCA concentrations in both surface tension and (19)F NMR experiments; in contrast, fluorescence allows for analysis of a wider range of PFCA concentrations and PFCA:albumin mole ratios. Results from this study indicate that fluorescence, though an indirect method, offers a more comprehensive picture of the nature of PFCA-albumin interactions.

    View details for DOI 10.1021/ac902238u

    View details for Web of Science ID 000273983700032

    View details for PubMedID 20039637

  • Measurement and modeling of polychlorinated biphenylbioaccumulation from sediment for the marine polychaete Neanthes arenaceodentata and response to sorbent amendment Environmental Science & Technology Janssen, Elisabeth, M.L., Croteau, M., Luoma, Samuel, N., Luthy, Richard, G. 2010; 8 (44): 2857 - 2863
  • Sorption of dichlorodiphenyltrichloroethane (DDT) and its metabolites by activated carbon in clean water and sediment slurries WATER RESEARCH Hale, S. E., Tomaszewski, J. E., Luthy, R. G., Werner, D. 2009; 43 (17): 4336-4346


    Polyethylene-water partitioning coefficients (K(PE)) and mass transfer coefficients (k(PE)) for the ortho and para isomers of the organochlorine pesticide dichlorodiphenyltrichloroethane (DDT) and its metabolites dichlorodiphenyldichloroethane (DDD), dichlorodiphenyldichloroethylene (DDE) and, dichlorodiphenylmonochloroethylene (DDMU) were measured. These data were used to derive activated carbon (AC) sorption isotherms in clean water in the sub-nanogram per litre free aqueous concentration range for a virgin and a regenerated AC. The sorption strength of AC for DDT and its metabolites was very high and logarithmic values of the AC-water partitioning coefficients, logK(AC), ranged from 8.47 to 9.26. A numerical mass transfer model was calibrated with this data to interpret previously reported reductions in DDT uptake by semipermeable membrane devices after AC amendment of sediment from Lauritzen Channel, California, USA. The activated carbon-water partitioning coefficient values (K(AC)) measured in clean water systems appear to overestimate the AC sorption capacity in sediment up to a factor 32 for DDT and its metabolites at long contact time with fine-sized AC. Modelling results show decreased attenuation of the AC sorption capacity with increased sediment-AC contact time. We infer that increased resistance in mass transfer of DDTs to sorption sites in the microporous region likely caused by deposits of dissolved organic matter in the macro- and mesopores of AC appears to be the most relevant fouling mechanism. These results suggest that DDTs may diffuse through possible deposits of dissolved organic matter over time, implying that the effects of sediment on the sorption of DDTs by AC may be more kinetic than competitive.

    View details for DOI 10.1016/j.watres.2009.06.031

    View details for Web of Science ID 000270629500026

    View details for PubMedID 19595428

  • Field Application of Activated Carbon Amendment for In-Situ Stabilization of Polychlorinated Biphenyls in Marine Sediment ENVIRONMENTAL SCIENCE & TECHNOLOGY Cho, Y., Ghosh, U., Kennedy, A. J., Grossman, A., Ray, G., Tomaszewski, J. E., Smithenry, D. W., Bridges, T. S., Luthy, R. G. 2009; 43 (10): 3815-3823


    We report results on the first field-scale application of activated carbon (AC) amendment to contaminated sediment for in-situ stabilization of polychlorinated biphenyls (PCBs). The test was performed on a tidal mud flat at South Basin, adjacent to the former Hunters Point Naval Shipyard, San Francisco Bay, CA. The major goals of the field study were to (1) assess scale up of the AC mixing technology using two available, large-scale devices, (2) validate the effectiveness of the AC amendment at the field scale, and (3) identify possible adverse effects of the remediation technology. Also, the test allowed comparison among monitoring tools, evaluation of longer-term effectiveness of AC amendment, and identification of field-related factors that confound the performance of in-situ biological assessments. Following background pretreatment measurements, we successfully incorporated AC into sediment to a nominal 30 cm depth during a single mixing event, as confirmed by total organic carbon and black carbon contents in the designated test plots. The measured AC dose averaged 2.0-3.2 wt% and varied depending on sampling locations and mixing equipment. AC amendment did not impact sediment resuspension or PCB release into the water column over the treatment plots, nor adversely impactthe existing macro benthic community composition, richness, or diversity. The PCB bioaccumulation in marine clams was reduced when exposed to sediment treated with 2% AC in comparison to the control plot Field-deployed semi permeable membrane devices and polyethylene devices showed about 50% reduction in PCB uptake in AC-treated sediment and similar reduction in estimated pore-water PCB concentration. This reduction was evident even after 13-month post-treatment with then 7 months of continuous exposure, indicating AC treatment efficacy was retained for an extended period. Aqueous equilibrium PCB concentrations and PCB desorption showed an AC-dose response. Field-exposed AC after 18 months retained a strong stabilization capability to reduce aqueous equilibrium PCB concentrations by about 90%, which also supports the long-term effectiveness of AC in the field. Additional mixing during or after AC deployment, increasing AC dose, reducing AC-particle size, and sequential deployment of AC dose will likely improve AC-sediment contact and overall effectiveness. The reductions in PCB availability observed with slow mass transfer under field conditions calls for predictive models to assess the long-term trends in pore-water PCB concentrations and the benefits of alternative in-situ AC application and mixing strategies.

    View details for DOI 10.1021/es802931c

    View details for Web of Science ID 000266046700066

    View details for PubMedID 19544893

  • Field application of activated carbon amendment for in situ stabilization of PCBs in sediment Luthy, R. G., Cho, Y., Ghosh, U., Kennedy, A. J., Bridges, T. S. AMER CHEMICAL SOC. 2009
  • The stability of marine sediments at a tidal basin in San Francisco Bay amended with activated carbon for sequestration of organic contaminants (vol 42, pg 15, 2008) WATER RESEARCH Zimmerman, J. R., Bricker, J. D., Jones, C., Dacunto, P. J., Street, R. L., Luthy, R. G. 2008; 42 (20): 5072-5072
  • Nitromusk compounds in San Francisco Bay sediments CHEMOSPHERE Rubinfeld, S. A., Luthy, R. G. 2008; 73 (6): 873-879


    Synthetic nitromusk fragrances are used in a wide variety of consumer products and can enter aquatic environments through wastewater effluent. Although nitromusks are known to be hydrophobic, little attention has been paid to their behavior in sediments. A sediment extraction method using sonication was developed and used to analyze samples from San Francisco Bay. Both musk xylene (MX) and musk ketone (MK) were found at low levels, with mean concentrations of 0.034 and 0.038ngg(-1), respectively. The highest concentrations were found in the southernmost region of the Bay. Samples were also analyzed from a nearby tidal channel fed by a wastewater treatment plant outfall. At this location both musk xylene and musk ketone were found at higher concentrations of 0.13-0.24ngg(-1) MX and 1.08-2.74ngg(-1) MK. A metabolite of musk xylene was also found at levels up to 4.08ngg(-1), suggesting that these metabolites may play an important role in the fate of nitromusk compounds. Concentrations of all three compounds were highest at the earliest of four sampling dates, and a geographic survey of sediments along the tidal channel showed that concentrations decreased rapidly with distance from the outfall and were close to background before the channel reached the Bay.

    View details for DOI 10.1016/j.chemosphere.2008.07.042

    View details for Web of Science ID 000260486600002

    View details for PubMedID 18783818

  • Measuring and modeling reduction of DDT availability to the water column and mussels following activated carbon amendment of contaminated sediment WATER RESEARCH Tomaszewski, J. E., McLeod, P. B., Luthy, R. G. 2008; 42 (16): 4348-4356


    A 28-day accumulation study demonstrated the use of mussel uptake, passive samplers, and biodynamic modeling to measure the reduction of dichlorodiphenyltrichloroethane (DDT) availability in the water column after the addition of activated carbon to contaminated sediment. Sediment collected from Lauritzen Channel, Richmond, California (16.5mg total DDT/kg) was mixed with either virgin activated carbon or a reactivated carbon for one month, after which a 28-day laboratory exposure study was completed. Mussels (Mytilus edulis) suspended above activated carbon-treated sediment accumulated significantly less total DDT in soft tissue, 91% and 84% for virgin and reactivated carbon, respectively, as compared to untreated sediment. Mussel tissue concentrations correlated to concentrations in semipermeable membrane devices (SPMDs) and polyethylene devices (PEDs) suspended over the same sediments. A biodynamic model that incorporated DDT water concentrations, either analytically measured or estimated from PED uptake, described mussel accumulation over time. Thus, passive samplers in combination with biodynamic modeling may provide an important screening tool for assessment of filter-feeding uptake and ecological risk to water-dwelling organisms exposed to aqueous phase hydrophobic organic contaminants.

    View details for DOI 10.1016/j.watres.2008.07.016

    View details for Web of Science ID 000260757300015

    View details for PubMedID 18723202

  • The stability of marine sediments at a tidal basin in San Francisco Bay amended with activated carbon for sequestration of organic contaminants WATER RESEARCH Zimmerman, J. R., Bricker, J. D., Jones, C., Dacunto, P. J., Street, R. L., Luthy, R. G. 2008; 42 (15): 4133-4145


    Recent laboratory studies show that adding activated carbon to marine sediments reduces the bioavailability of persistent organic contaminants, such as polychlorinated biphenyls, to benthic organisms. The present work investigates how mixing activated carbon into cohesive sediment affects the stability of sediment obtained from the intertidal zone at the Hunters Point Naval Shipyard Superfund site in South Basin, San Francisco Bay, CA. Our results show for these sediments that mixing activated carbon into sediment does not significantly affect stability of surface sediments, as measured by sediment erosion rate and critical shear stress for incipient motion, thus supporting the potential field application of this technique for in situ stabilization of persistent organic contaminants. Hydrodynamic modeling was used to estimate the maximum bottom shear stress encountered during high-wind storm events at the estuarine inlet from which the sediments were obtained. Comparison of estimated bottom shear stresses with measured critical shear stresses shows that surface sediments will not erode under normal, non-storm conditions. Bottom shear stresses caused by large waves under infrequent high-wind storm conditions may erode surface sediments for short periods of time. We conclude from sediment stability tests and hydrodynamic modeling that mixing activated carbon amendment with cohesive sediment at selected locations within South Basin will not reduce surface sediment stability nor result in significant erosion of treated sediments.

    View details for DOI 10.1016/j.watres.2008.05.023

    View details for Web of Science ID 000259919800013

    View details for PubMedID 18692860

  • Field deployment of polyethylene devices to measure PCB concentrations in pore water of contaminated sediment ENVIRONMENTAL SCIENCE & TECHNOLOGY Tomaszewski, J. E., Luthy, R. G. 2008; 42 (16): 6086-6091


    Sediment pore water concentrations of polychlorinated biphenyls (PCBs) in a contaminated mudflat in San Francisco Bay, CA were determined by field-deployed polyethylene devices (PEDs). Sequential sampling of PEDs deployed in the field showed large differences in uptake rates and time to equilibrium compared to PEDs mixed with field-collected sediment in the laboratory. We demonstrate a modeling approach that involves the use of impregnated performance reference compounds (PRCs) and interpretation of the data either by PCB molar volume adjustment or environmental adjustment factors to measure pore water concentrations of 118 PCB congeners. Both adjustment methods predicted comparable sampling rates, and PCB pore water concentrations estimated by use of the molar volume adjustment method were similar to values analytically measured in pore waters from the laboratory and field. The utility of PEDs for sampling pore water in the field was evaluated at a tidal mudflat amended with activated carbon to sequester PCBs. Pore water concentrations decreased up to 60% within 18 months after activated carbon amendment, as compared to a mechanical-mixed control plot Results of this study illustrate PEDs provide an inexpensive, in situ method to measure total PCB contamination in sediment pore water using a small set of PRCs.

    View details for DOI 10.1021/es800582a

    View details for Web of Science ID 000258439600041

    View details for PubMedID 18767670

  • Modeling PAH mass transfer in a slurry of contaminated soil or sediment amended with organic sorbents WATER RESEARCH Ahn, S., Werner, D., Luthy, R. G. 2008; 42 (12): 2931-2942


    A three-compartment kinetic partitioning model was employed to assess contaminant mass transfer and intraparticle diffusion in systems comprising dense slurries of polluted soil or aquifer sediment with or without sorbent amendments to sequester polycyclic aromatic hydrocarbons (PAHs). The model was applied to simulate temporal changes in aqueous and particle-bound PAH concentrations comparing different pollution sources (heavy oil or tar sludge) and various sorbent amendments (polyoxymethylene (POM), coke breeze, and activated carbon). For the model evaluation, all the parameters needed were directly measured from a series of experiments, allowing full calibration and verification of model predictions without parameter fitting. The numerical model reproduced two separate laboratory-scale experiments reasonably: PAH uptake in POM beads and PAH uptake by semipermeable membrane devices. PAH mass transfer was then simulated for various scenarios, considering different sorbent doses and mass transfer rates as well as biodegradation. Such model predictions provide a quick assessment tool for identifying mass transfer limitations during washing, stabilization, or bioslurry treatments of polluted soil or sediment in mixed systems. It appears that PAHs would be readily released from materials contaminated by small oil droplets, but not tar decanter sludge. Released PAHs would be sequestered rapidly by activated carbon amendment but to a much lesser extent by coke breeze. If sorbing black carbon is present in the slurries, POM pellets would not be effective as a sequestration amendment. High first-order biodegradation rates in the free aqueous phase, e.g., in the order of 0.001 s(-1) for phenanthrene, would be required to compete effectively with adsorption and mass transfer for strong sorbents.

    View details for DOI 10.1016/j.watres.2008.03.011

    View details for Web of Science ID 000257649100010

    View details for PubMedID 18456306

  • Uptake of PAHs into polyoxymethylene and application to oil-soot (lampblack)-impacted soil samples CHEMOSPHERE Hong, L., Luthy, R. G. 2008; 72 (2): 272-281


    Polyoxymethylene (POM) is a polymeric material used increasingly in passive sampling of hydrophobic organic contaminants such as PAHs and PCBs in soils and sediments. In this study, we examined the sorption behavior of 12 PAH compounds to POM and observed linear isotherms spanning two orders of magnitude of aqueous concentrations. Uptake kinetic studies performed in batch systems for up to 54 d with two different volume ratios of POM-to-aqueous phase were evaluated with coupled diffusion and mass transfer models to simulate the movement of PAHs during the uptake process and to assess the physicochemical properties and experimental conditions that control uptake rates. Diffusion coefficients of PAHs in POM were estimated to be well correlated with diffusants' molecular weights as D(POM) proportional, variant(MW)(-3), descending from 2.3 x 10(-10) cm(2) s(-1) for naphthalene to 7.0 x 10(-11) cm(2) s(-1) for pyrene. The uptake rates for PAHs with log K(ow)<5.8 were controlled by the POM phase and the hydrophobicity of PAH compounds. For more hydrophobic PAH compounds, the aqueous boundary layer played an increasingly important role in determining the overall mass transfer rate. The POM partitioning technique was demonstrated to agree well with two other procedures for measuring PAH soil-water distribution coefficients in oil-soot (lampblack) containing soil samples.

    View details for DOI 10.1016/j.chemosphere.2008.01.028

    View details for Web of Science ID 000256737900018

    View details for PubMedID 18334261

  • Aerobic biotransformation and fate of N-ethyl perfluorooctane sulfonamidoethanol (N-EtFOSE) in activated sludge ENVIRONMENTAL SCIENCE & TECHNOLOGY Rhoads, K. R., Janssen, E. M., Luthy, R. G., Criddle, C. S. 2008; 42 (8): 2873-2878


    Processes affecting the fate of perfluorinated organics are of increasing concern due to the global dispersal, persistence, and bioaccumulation of these contaminants. The volatile compound N-ethyl perfluorooctane sulfonamidoethanol (N-EtFOSE) and its phosphate esters have been used in protective surface coatings. In this report, we describe the fate of N-EtFOSE in aerobic batch assays. These assays were performed using undiluted activated sludge in serum bottles that were sealed to prevent the escape of N-EtFOSE and volatile transformation products. Separate assays were performed with N-EtFOSE and reported transformation products. N-EtFOSE degraded to N-ethyl perfluorooctane sulfonamido acetic acid (N-EtFOSAA) with an observed first-order rate of 0.99 +/- 0.08 day(-1) and a pseudosecond order rate of 0.26 +/- 0.02 L/mg VSS day(-1). N-EtFOSAA underwent further transformation at a slower rate (0.093 +/- 0.012 day(-1)) to N-ethylperfluorooctane sulfonamide (N-EtFOSA). N-EtFOSA then transformed to perfluorooctane sulfonamide (FOSA). FOSA transformed to perfluorooctane sulfinate (PFOSI), and PFOSI transformed to perfluorooctane sulfonate (PFOS). Perfluorooctanoic acid (PFOA) was not detected as a transformation product of any compound. Using the measured rate of N-EtFOSE biotransformation and literature values for phase partitioning and mass transfer in aeration basins, we modeled the fate of N-EtFOSE in a typical activated sludge aeration basin open to the atmosphere. The model predicts that 76% of the N-EtFOSE is stripped into the atmosphere, 5% sorbs to waste solids, 13% undergoes transformation to N-EtFOSAA, and 6% is discharged in the wastewater effluent.

    View details for DOI 10.1021/es702866c

    View details for Web of Science ID 000254890400033

    View details for PubMedID 18497137

  • ANYL 155-Investigation of the binding of perfluorocarboxylates to a model serum protein: A comparison of analytical methods MacManus-Spencer, L. A., Tse, M. L., Bische, H., Luthy, R. G. AMER CHEMICAL SOC. 2008
  • Biodynamic modeling of PCB uptake by Macoma balthica and Corbicula fluminea from sediment amended with activated carbon ENVIRONMENTAL SCIENCE & TECHNOLOGY McLeod, P. B., Luoma, S. N., Luthy, R. G. 2008; 42 (2): 484-490


    Activated carbon amendment was assessed in the laboratory as a remediation strategy for freshwater sediment contaminated with polychlorinated biphenyls (PCBs) from the Grasse River (near Massena, NY). Three end points were evaluated: aqueous equilibrium PCB concentration, uptake into semipermeable membrane devices (SPMDs), and 28-day bioaccumulation in the clam Corbicula fluminea. PCB uptake by water, SPMDs, and clams followed similar trends, with reductions increasing as a function of carbon dose. Average percent reductions in clam tissue PCBs were 67, 86, and 95% for activated carbon doses of 0.7, 1.3, and 2.5% dry wt, respectively. A biodynamic model that incorporates sediment geochemistry and dietary and aqueous uptake routes was found to agree well with observed uptake by C. fluminea in our laboratory test systems. Results from this study were compared to 28-day bioaccumulation experiments involving PCB-contaminated sediment from Hunters Point Naval Shipyard (San Francisco Bay, CA) and the clam Macoma balthica. Due to differences in feeding strategy, M. balthica deposit-feeds whereas C. fluminea filter-feeds, the relative importance of the aqueous uptake route is predicted to be much higher for C. fluminea than for M. balthica. Whereas M. balthica takes up approximately 90% of its body burden through sediment ingestion, C. fluminea only accumulates approximately 45% via this route. In both cases, results strongly suggest that it is the mass transfer of PCBs from native sediment to added carbon particles, not merely reductions in aqueous PCB concentrations, that effectively reduces PCB bioavailability and uptake by sediment-dwelling organisms.

    View details for DOI 10.1021/es070139a

    View details for Web of Science ID 000252317700030

    View details for PubMedID 18284151

  • Field methods for amending marine sediment with activated carbon and assessing treatment effectiveness MARINE ENVIRONMENTAL RESEARCH Cho, Y., Smithenry, D. W., Ghosh, U., Kennedy, A. J., Millward, R. N., Bridges, T. S., Luthy, R. G. 2007; 64 (5): 541-555


    Previous laboratory studies have shown reductions in PCB bioavailability for sediments amended with activated carbon (AC). Here we report results on a preliminary pilot-scale study to assess challenges in scaling-up for field deployment and monitoring. The goals of the preliminary pilot-scale study at Hunters Point Shipyard (San Francisco, USA) were to (1) test the capabilities of a large-scale mixing device for incorporating AC into sediment, (2) develop and evaluate our field assessment techniques, and (3) compare reductions in PCB bioavailability found in the laboratory with well-mixed systems to those observed in the field with one-time-mixed systems. In this study we successfully used a large-scale device to mix 500kg of AC into a 34.4m(2) plot to a depth of 1ft, a depth that includes the majority of the biologically active zone. Our results indicate that after 7 months of AC-sediment contact in the field, the 28-day PCB bioaccumulation for the bent-nosed clam, Macoma nasuta, field-deployed to this AC-amended sediment was approximately half of the bioaccumulation resulting from exposure to untreated sediment. Similar PCB bioaccumulation reductions were found in laboratory bioassays conducted on both the bivalve, M. nasuta and the estuarine amphipod, Leptocheirus plumulosus, using sediment collected from the treated and untreated field plots one year after the AC amendment occurred. To further understand the long-term effectiveness of AC as an in situ treatment strategy for PCB-contaminated sediments under field conditions, a 3-year comprehensive study is currently underway at Hunters Point that will compare the effectiveness of two large-scale mixing devices and include both unmixed and mixed-only control plots.

    View details for DOI 10.1016/j.marenvres.2007.04.006

    View details for Web of Science ID 000251201400001

    View details for PubMedID 17570482

  • Activated carbon amendment as a treatment for residual DDT in sediment from a superfund site in San Francisco Bay, Richmond, California, USA ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY Tomaszewski, J. E., Werner, D., Luthy, R. G. 2007; 26 (10): 2143-2150


    Pesticide formulators formerly operating at Lauritzen Channel, a portion of San Francisco Bay near Richmond (CA, USA), caused contamination of sediment with dichlorodiphenyltrichloroethane (DDT). The present study evaluated the distribution of residual DDT in channel sediment six years following extensive remedial dredging. High DDT concentrations (up to 252 mg/ kg) were found in Young Bay Mud sampled across the channel. Particle analyses showed most of the contamination is contained in the clay/silt sediment fraction, and desorption tests showed that availability is greater for DDT metabolites than parent DDT. The present study examined the feasibility of using activated carbon amendment to sequester DDT from sediment, including an evaluation of reactivated carbon as a less costly alternative to virgin activated carbons. Treatment success of activated carbon amendment to sediment collected from Lauritzen Channel was measured by reductions in aqueous equilibrium concentrations and uptake in semipermeable membrane devices (SPMDs). Four different activated carbons were tested and, after one month of treatment with 3.2 weight % carbon, DDT aqueous equilibrium concentrations were reduced up to 83% and SPMD uptake was reduced up to 91%. Reactivated carbon was comparable with virgin carbons in all tests. Reduction in SPMD uptake of DDT by treatment with 3.2% reactivated carbon increased to 99% after 26 months of treatment. The effectiveness of activated carbon was dependent on the type, size, dose, and contact time. The results show the potential usefulness of activated carbon amendment as a follow-up remedial technology for management of residuals after dredging contaminated sediment.

    View details for Web of Science ID 000249528000015

    View details for PubMedID 17867891

  • Bioaccumulation of perfluorochemicals in sediments by the aquatic oligochaete Lumbriculds variegatus ENVIRONMENTAL SCIENCE & TECHNOLOGY Higgins, C. P., McLeod, P. B., Macmanus-Spencer, L. A., Luthy, R. G. 2007; 41 (13): 4600-4606


    Bioaccumulation of perfluoroalkyl sulfonates, perfluorocarboxylates, and 2-(N-ethylperfluorooctane sulfonamido) acetic acid (N-EtFOSAA) from laboratory-spiked and contaminated field sediments was assessed using the freshwater oligochaete, Lumbriculus variegatus. Semistatic batch experiments were conducted to monitor the biological uptake of these perfluorochemicals (PFCs) over 56 days. The elimination of PFCs was measured as the loss of PFCs in L. variegatus exposed to PFC-spiked sediment for 28 days and then transferred to clean sediment. The resultant data suggest that PFCs in sediments are readily bioavailable and that bioaccumulation from sediments does not continually increase with increasing perfluorocarbon chain length. Perfluorooctane sulfonate (PFOS) and perfluorononanoate were the most bioaccumulative PFCs, as measured by laboratory-based estimated steady-state biota sediment accumulation factors (BSAFs) and BSAFs measured using contaminated field sediments. Elimination rate constants for perfluoroalkyl sulfonates and perfluorocaroboxylates were generally smaller than those previously measured for other organic contaminants. Last, a PFOS precursor, N-EtFOSAA, accumulated in the worm tissues and appeared to undergo biotransformation to PFOS and other PFOS precursors. This suggests that N-EtFOSAA, which has been detected in sediments and sludge often at levels exceeding PFOS, may contribute to the bioaccumulation of PFOS in aquatic organisms.

    View details for DOI 10.1021/es062792o

    View details for Web of Science ID 000247782500027

    View details for PubMedID 17695903

  • Modeling sorption of anionic surfactants onto sediment materials: An a priori approach for perfluoroalkyl surfactants and linear alkylbenzene sulfonates ENVIRONMENTAL SCIENCE & TECHNOLOGY Higgins, C. P., Luty, R. G. 2007; 41 (9): 3254-3261


    A mechanistically derived model predicting the sorption of anionic surfactants to sediments was developed and evaluated for three classes of surfactants: perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and linear alkylbenzene sulfonates. The model includes both hydrophobic and electrostatic components and estimates the contribution of each to the sediment-water distribution coefficient (Kd) using Gibbs free energy terms. The hydrophobic free energy term was calculated from the aqueous solubilities of non-charged alkylbenzene or perfluoroalkane analogs and prior observations of increases in Kd values with increasing chain lengths. The electrostatic term was calculated from aqueous solution measurements using the non-ideal competitive adsorption Donnan (NICA-Donnan) model. The NICA-Donnan calculations were performed using parameters previously derived for generic humic acids. These two terms were coupled by multiplying by the fraction of organic carbon in the sediment, foc, and a single fitting parameter, Faccess, the volumetric fraction of organic carbon accessible to the sorbing surfactant. The combined model accurately predicted the sediment-water distribution coefficients for all three classes of anionic surfactants. In its current formulation, the model was unable to capture the slight degree of isotherm nonlinearity observed for these surfactants.

    View details for DOI 10.1021/es062449j

    View details for Web of Science ID 000246371100040

    View details for PubMedID 17539534

  • Biological uptake of polychlorinated biphenyls by Macoma balthica from sediment amended with activated carbon ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY McLeod, P. B., Van den Heuvel-Greve, M. J., Luoma, S. N., Luthy, R. G. 2007; 26 (5): 980-987


    This work characterizes the efficacy of activated carbon amendment in reducing polychlorinated biphenyl (PCB) bioavailability to clams (Macoma balthica) from field-contaminated sediment (Hunters Point Naval Shipyard, San Francisco Bay, CA, USA). Test methods were developed for the use of clams to investigate the effects of sediment amendment on biological uptake. Sediment was mixed with activated carbon for one month. Bioaccumulation tests (28 d) were employed to assess the relationships between carbon dose and carbon particle size on observed reductions in clam biological uptake of PCBs. Extraction and cleanup protocols were developed for the clam tissue. Efficacy of activated carbon treatment was found to increase with both increasing carbon dose and decreasing carbon particle size. Average reductions in bioaccumulation of 22, 64, and 84% relative to untreated Hunters Point sediment were observed for carbon amendments of 0.34, 1.7, and 3.4%, respectively. Average bioaccumulation reductions of 41, 73, and 89% were observed for amendments (dose = 1.7% dry wt) with carbon particles of 180 to 250, 75 to 180, and 25 to 75 microm, respectively, in diameter, indicating kinetic phenomena in these tests. Additionally, a biodynamic model quantifying clam PCB uptake from water and sediment as well as loss through elimination provided a good fit of experimental data. Model predictions suggest that the sediment ingestion route contributed 80 to 95% of the PCB burdens in the clams.

    View details for Web of Science ID 000245749500021

    View details for PubMedID 17521146

  • Availability of polycyclic aromatic hydrocarbons from lampblack-impacted soils at former oil-gas plant sites in California, USA ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY Hong, L., Luthy, R. G. 2007; 26 (3): 394-405


    Lampblack-impacted soils at former oil-gas plant sites in California, USA, were characterized to assess the sorption of polycyclic aromatic hydrocarbons (PAHs) and the concentration-dependent effects of a residual oil tar phase on sorption mechanism and availability of PAHs. Nuclear magnetic resonance spectroscopy demonstrated similar aromaticity for both lampblack carbon and the oil tar phase, with pronounced resonance signals in the range of 100 to 150 ppm. Scanning-electron microscopic images revealed a physically distinct oil tar phase, especially at high concentrations in lampblack, which resulted in an organic-like film structure when lampblack particles became saturated with the oil tar. Sorption experiments were conducted on a series of laboratory-prepared lampblack samples to systematically evaluate influences of an oil tar phase on PAH sorption to lampblack. Results indicate that the sorption of PAHs to lampblack exhibits a competition among sorption phases at low oil tar contents when micro- and mesopores are accessible. When the oil tar content increases to more than 5 to 10% by weight, this tar phase fills small pores, reduces surface area, and dominates PAH sorption on lampblack surface. A new PAH partitioning model, Kd = KLB-C(1 - ftar)alpha + ftarKtar (alpha = empirical exponent), incorporates these effects in which the control of PAH partitioning transits from being dominated by sorption in lampblack (KLB-C) to absorption in oil tar (Ktar), depending on the fraction of tar (ftar). This study illustrates the importance of understanding interactions among PAHs, oil tar, and lampblack for explaining the differences in availability of PAHs among site soils and, consequently, for refining site-specific risk assessment and establishing soil cleanup levels.

    View details for Web of Science ID 000244241600003

    View details for PubMedID 17373502

  • Sorption of perfluorinated surfactants on sediments ENVIRONMENTAL SCIENCE & TECHNOLOGY Higgins, C. P., Luthy, R. G. 2006; 40 (23): 7251-7256


    The sorption of anionic perfluorochemical (PFC) surfactants of varying chain lengths to sediments was investigated using natural sediments of varying iron oxide and organic carbon content. Three classes of PFC surfactants were evaluated for sorptive potential: perfluorocarboxylates, perfluorosulfonates, and perfluorooctyl sulfonamide acetic acids. PFC surfactant sorption was influenced by both sediment-specific and solution-specific parameters. Sediment organic carbon, rather than sediment iron oxide content, was the dominant sediment-parameter affecting sorption, indicating the importance of hydrophobic interactions. However, sorption also increased with increasing solution [Ca2+] and decreasing pH, suggesting that electrostatic interactions play a role. Perfluorocarbon chain length was the dominant structural feature influencing sorption, with each CF2 moiety contributing 0.50-0.60 log units to the measured distribution coefficients. The sulfonate moiety contributed an additional 0.23 log units to the measured distribution coefficient, when compared to carboxylate analogs. In addition, the perfluorooctyl sulfonamide acetic acids demonstrated substantially stronger sorption than perfluorooctane sulfonate (PFOS). These data should prove useful for modeling the environmental fate of this class of contaminants.

    View details for DOI 10.1021/es061000n

    View details for Web of Science ID 000242367100027

    View details for PubMedID 17180974

  • Fluorochemical mass flows in a municipal wastewater treatment facility ENVIRONMENTAL SCIENCE & TECHNOLOGY Schultz, M. M., Higgins, C. P., Huset, C. A., Luthy, R. G., Barofsky, D. F., Field, J. A. 2006; 40 (23): 7350-7357


    Fluorochemicals have widespread applications and are released into municipal wastewater treatment plants via domestic wastewater. A field study was conducted at a full-scale municipal wastewater treatment plant to determine the mass flows of selected fluorochemicals. Flow-proportional, 24 h samples of raw influent, primary effluent, trickling filter effluent, secondary effluent, and final effluent and grab samples of primary, thickened, activated, and anaerobically digested sludge were collected over 10 days and analyzed by liquid chromatography electrospray-ionization tandem mass spectrometry. Significant decreases in the mass flows of perfluorohexane sulfonate and perfluorodecanoate occurred during trickling filtration and primary clarification, while activated sludge treatment decreased the mass flow of perfluorohexanoate. Mass flows of the 6:2 fluorotelomer sulfonate and perfluorooctanoate were unchanged as a result of wastewater treatment, which indicates that conventional wastewater treatment is not effective for removal of these compounds. A net increase in the mass flows for perfluorooctane and perfluorodecane sulfonates occurred from trickling filtration and activated sludge treatment. Mass flows for perfluoroalkylsulfonamides and perfluorononanoate also increased during activated sludge treatment and are attributed to degradation of precursor molecules.

    View details for DOI 10.1021/es061025m

    View details for Web of Science ID 000242367100041

    View details for PubMedID 17180988

  • Nanometer-scale chemical heterogeneities of black carbon materials and their impacts on PCB sorption properties: Soft X-ray spectromicroscopy study ENVIRONMENTAL SCIENCE & TECHNOLOGY Yoon, T. H., Benzerara, K., Ahn, S., Luthy, R. G., Tyliszczak, T., Brown, G. E. 2006; 40 (19): 5923-5929


    Synchrotron-based soft X-ray spectromicroscopy was used to probe nanometer-scale chemical heterogeneities of black carbon (BC) materials, including anthracite coal, coke, and activated carbon (AC), and to study their impact on the partitioning of one type of polychlorinated biphenyls (PCB-166: 2,3,4,4',5,6 hexachloro biphenyl) onto AC particles. Various carbon species (e.g., aromatic, ketonic/ phenolic, and carboxylic functional groups) were found in all of the BC materials examined, and impurities (e.g., carbonate and potassium ions in anthracite coal) were identified in nanometer-scale regions of these samples. We show that these chemical heterogeneities in AC particles influence their sorption of hydrophobic organic compounds (HOCs). PCB-166 was found to accumulate preferentially on AC particles with the highest content of aromatic functionalities. These new findings from X-ray spectromicroscopy have the following implications for the role of BC materials in the environment: (1) the functional groups of BC materials vary on a 25-nanometer scale, and so does the abundance of the HOCs; (2) molecular-level characterization of HOC sorption preferences on AC will lead to an improved understanding of AC sorption properties for the remediation of HOCs in soils and sediments.

    View details for DOI 10.1021/es060173+

    View details for Web of Science ID 000240826000022

    View details for PubMedID 17051780

  • Human development is linked to multiple water body impairments along the California coast ESTUARIES AND COASTS Handler, N. B., Payran, A., Higgins, C. P., Luthy, R. G., Boehm, A. B. 2006; 29 (5): 860-870
  • Modeling perfluorochemical surfactant sorption onto sediment materials: An a priori approach Higgins, C. P., Luthy, R. G. AMER CHEMICAL SOC. 2006: 614-614
  • Implications for perfluorochemical ecotoxicology: Inhibition and induction of an efflux transporter in the marine mussel, Mytilus californianus Stevenson, C., Macmanus-Spencer, L. A., Luckenbach, T., Luthy, R. G., Epel, D. AMER CHEMICAL SOC. 2006: 608-608
  • New perspectives on perfluorochemical ecotoxicology: inhibition and induction of an efflux transporter in the marine mussel, Mytilus californianus ENVIRONMENTAL SCIENCE & TECHNOLOGY Stevenson, C. N., Macmanus-Spencer, L. A., Luckenbach, T., Luthy, R. G., Epel, D. 2006; 40 (17): 5580-5585


    The toxicological effects of perfluoroalkyl acids on the p-glycoprotein (p-gp) cellular efflux transporter were investigated using the marine mussel Mytilus californianus as a model system. Four of the perfluoroalkyl acids studied exhibit chemosensitizing behavior, significantly inhibiting p-gp transporter activity. The inhibitory potency is maximal for the longer chain acids perfluorononanoate (PFNA) and perfluorodecanoate (PFDA), with average IC50 values of 4.8 and 7.1 microM, respectively. Results indicate that PFNA inhibits p-gp by an indirect mechanism, and this inhibition is reversible and accompanied by a rapid loss of PFNA from the tissue. In addition, PFNA induces expression of the p-gp transporter after a 2-h exposure, a stress response that may result in a metabolic cost to the organism. Given that most organisms, including humans, share efflux transporters as a first line of defense against toxicants, the results of this study may have broader implications for the ecotoxicology of perfluoroalkyl acids.

    View details for DOI 10.1021/es0602593

    View details for Web of Science ID 000240130200067

    View details for PubMedID 16999143

  • Modeling polychlorinated biphenyl mass transfer after amendment of contaminated sediment with activated carbon ENVIRONMENTAL SCIENCE & TECHNOLOGY Werner, D., Ghosh, U., Luthy, R. G. 2006; 40 (13): 4211-4218


    The sorption kinetics and concentration of polychlorinated biphenyls (PCBs) in historically polluted sediment is modeled to assess a remediation strategy based on in situ PCB sequestration by mixing with activated carbon (AC). We extend our evaluation of a model based on intraparticle diffusion by including a biomimetic semipermeable membrane device (SPMD) and a first-order degradation rate for the aqueous phase. The model predictions are compared with the previously reported experimental PCB concentrations in the bulk water phase and in SPMDs. The simulated scenarios comprise a marine and a freshwater sediment, four PCB congeners, two AC grain sizes, four doses of AC, and comparison with laboratory experiments for up to 540 days of AC amendment slowly mixed with sediment. The model qualitatively reproduces the observed shifts in the PCB distribution during repartitioning after AC amendment but systematically overestimates the overall effect of the treatment in reducing aqueous and SPMD concentrations of PCBs by a factor of 2-6. For our AC application in sediment, competitive sorption of the various solutes apparently requires a reduction by a factor of 16 of the literature values for the AC-water partitioning coefficient measured in pure aqueous systems. With this correction, model results and measurements agree within a factor of 3. We also discuss the impact of the nonlinearity of the AC sorption isotherm and first-order degradation in the aqueous phase. Regular mixing of the sediment accelerates the benefit of the proposed amendment substantially. But according to our scenario, after AC amendment is homogeneously mixed into the sediment and then left undisturbed, aqueous PCB concentrations tend toward the same reduction after approximately 5 or more years.

    View details for DOI 10.1021/es052215k

    View details for Web of Science ID 000238645400032

    View details for PubMedID 16856737

  • Treatment and containment of contaminated sediments ASSESSMENT AND REMEDIATION OF CONTAMINATED SEDIMENTS Tomaszewski, J. E., Smithenry, D. W., Cho, Y., Luthy, R. G., Lowry, G. V., Reible, D., Macek, T., Sura, M., Chrastilova, Z., Demnerova, K., Mackova, M., Pavlikova, D., Szekeres, M., Sylvestre, M. 2006; 73: 137-178
  • Phenanthrene and pyrene sorption and intraparticle diffusion in polyoxymethylene, coke, and activated carbon ENVIRONMENTAL SCIENCE & TECHNOLOGY Ahn, S., Werner, D., Karapanagioti, H. K., McGlothlin, D. R., Zare, R. N., Luthy, R. G. 2005; 39 (17): 6516-6526


    We report sorption isotherms and uptake kinetics for phenanthrene and pyrene with three organic model sorbents: polyoxymethylene (POM), coke, and activated carbon. We combine batch equilibration and kinetic experiments with the direct observation of the long-term diffusion of phenanthrene and pyrene as measured within cross-sectioned particles using microprobe laser-desorption laser-ionization mass spectroscopy (muL2MS). For POM pellets, the intraparticle concentration profiles predicted from kinetic batch experiments and a polymer diffusion model with spherical geometry are in agreement with the independent muL2MS measurements. For coke particles, the apparent diffusivities decreased with smaller particle size. These trends in diffusivities were described by a sorption-retarded pore diffusion model with a particle-size-dependent solid-water partitioning coefficient obtained from apparent equilibrium observed in the kinetic batch studies. For activated carbon, the muL2MS measurements showed faster radial diffusion of phenanthrene and pyrene into the particle interior than predicted from diffusion models based on a single sorption domain and diffusivity. A branched pore kinetic model, comprising polycyclic aromatic hydrocarbon (PAH) macropore diffusion with kinetic exchange of PAH between macroporous and microporous domains, fits the experimental observations better. Because of parallel macro- and microdiffusion processes, nonlinear sorption isotherms, and a concentration-dependent diffusivity, it is not possible to make independent parameter estimations for intraparticle diffusion in activated carbon using our present procedures.

    View details for DOI 10.1021/es050113o

    View details for Web of Science ID 000231723800035

    View details for PubMedID 16190207

  • Physicochemical characterization of coke-plant soil for the assessment of polycyclic aromatic hydrocarbon availability and the feasibility of phytoremediation ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY Ahn, S., Werner, D., Luthy, R. G. 2005; 24 (9): 2185-2195


    Coke oven site soil was characterized to assess the particle association and availability of polycyclic aromatic hydrocarbons (PAHs). We identified various carbonaceous materials including coal, coke, pitch, and tar decanter sludge. Most of the PAHs were associated with the polymeric matrix of tar sludge or hard pitch as discrete particles, coatings on soil mineral particles, or complex aggregates. The PAH availability from these particles was very low due to hindered diffusive release from solid tar or pitch with apparent diffusivities of 6 x 10(-15) for phenanthrene, 3 x 10(-15) for pyrene, and 1 x 10(-15) cm2/s for benzo[a]pyrene. Significant concentrations of PAHs were observed in the interior of solid tar aggregates with up to 40,000 mg/kg total PAHs. The release of PAHs from the interior of such particles requires diffusion over a substantial distance, and semipermeable membrane device tests confirmed a very limited availability of PAHs. These findings explain the results from three years of phytoremediation of the site soil, for which no significant changes in the total PAH concentrations were observed in the test plot samples. The observed low bioavailability of PAHs probably inhibited PAH phytoremediation, as diffusion-limited mass transfer would limit the release of PAHs to the aqueous phase.

    View details for Web of Science ID 000231341300010

    View details for PubMedID 16193745

  • Preliminary field testing of activated carbon mixing and in situ stabilization of PCBs in sediment Cho, Y., Smithenry, D. W., Luthy, R. G. AMER CHEMICAL SOC. 2005: U1591-U1591
  • Use of black carbon to alter the bioavailability of contaminants in sediments Millward, R. N., Burgess, R. M., Ho, K. T., Bridges, T. S., Lotufo, G. R., Luthy, R. G., Ghosh, U. AMER CHEMICAL SOC. 2005: U1508-U1508
  • Effects of dose and particle size on activated carbon treatment to sequester polychlorinated biphenyls and polycyclic aromatic hydrocarbons in marine sediments ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY Zimmerman, J. R., Werner, D., Ghosh, U., Millward, R. N., Bridges, T. S., Luthy, R. G. 2005; 24 (7): 1594-1601


    Recent laboratory studies show that mixing activated carbon with contaminated sediment reduces the chemical and biological availability of hydrophobic organic contaminants. In this study, we test the effects of varying the activated carbon dose and particle size in reducing the aqueous availability of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) and the uptake of PCBs by two benthic organisms. We mixed PCB- and PAH-contaminated sediment from Hunters Point Naval Shipyard, San Francisco Bay (CA, USA), for one month with activated carbon, at doses of 0.34, 1.7, and 3.4% dry mass basis. We found that increasing the carbon dose increased the effectiveness in reducing PCB bioaccumulation. In 56-d uptake tests with the benthic organisms Neanthes arenaceodentata and Leptocheirus plumulosus, PCB bioaccumulation was reduced by 93 and 90%, respectively, with 3.4% carbon. Increasing the dose also increased the effectiveness in reducing PCB and PAH aqueous concentrations and uptake by semipermeable membrane devices and quiescent flux of PCBs to overlying water. Decreasing activated carbon particle size increased treatment effectiveness in reducing PCB aqueous concentration, and larger-sized activated carbon (400-1,700 microm) was ineffective with a contact period of one month. We invoke a numerical model based on intraparticle diffusion in sediment and activated carbon particles to help interpret our experimental results. This model was useful in explaining the trends for the effect of activated carbon dose and particle size on PCB aqueous concentrations in well-mixed systems.

    View details for Web of Science ID 000229960700003

    View details for PubMedID 16050574

  • Improving risk assessments for manufactured gas plant soils by measuring PAH availability. Integrated environmental assessment and management Stroo, H. F., Nakles, D. V., Kreitinger, J. P., Loehr, R. C., Hawthorne, S. B., Luthy, R. G., Holman, H., LaPierre, A. 2005; 1 (3): 259-266


    Remediation of soils at oil-gas manufactured gas plant (MGP) sites is driven primarily by the human health risks posed by the carcinogenic polycyclic aromatic hydrocarbons (PAHs), particularly benzo[a]pyrene (BaP), that are associated with lampblack residues. Although PAHs on lampblack are tightly sorbed, risk assessments do not account for this reduced availability. A multi-investigator study of 7 oil-gas MGP site soil samples demonstrated that the dermal and ingestion absorption factors are far lower than current default assumptions used in risk assessments. Using these sample-specific absorption factors in standard risk assessment equations increased risk-based cleanup levels by a factor of 72 on average (with a range from 23 to 142 times the default level). The rapidly released fraction of the BaP in each sample, as measured by supercritical fluid extraction, was closely correlated (r2 = 0.96) to these calculated cleanup levels. The weight of evidence developed during this research indicates that the risks posed by PAHs on lampblack are far less than assumed when using default absorption factors and that a tiered evaluation protocol employing chemical analyses, chemical release data, and in vitro bioassays can be used to establish more realistic site-specific criteria.

    View details for PubMedID 16639887

  • Quantitative determination of perfluorochemicals in sediments and domestic sludge ENVIRONMENTAL SCIENCE & TECHNOLOGY Higgins, C. P., Field, J. A., Criddle, C. S., Luthy, R. G. 2005; 39 (11): 3946-3956


    Perfluorochemicals (PFCs) are the subject of increasingly intense environmental research. Despite their detection both in biota and in aqueous systems, little attention has been paid to the possible presence of this class of compounds in solid environmental matrixes. The limited available data indicate that some PFCs such as perfluorooctane sulfonate (PFOS) may strongly sorb to solids, and sewage sludge is widely suspected as a major sink of PFCs entering municipal waste streams. A quantitative analytical method was developed that consists of liquid solvent extraction of the analytes from sediments and sludge, cleanup via solid-phase extraction, and injection of the extracts with internal standards into a high-performance liquid chromatography (HPLC) system coupled to a tandem mass spectrometer (LC/MS/MS). The limits of detections of the method were analyte and matrix dependent, but ranged from 0.7 to 2.2 ng/g and 0.041 to 0.246 ng/g (dry weight) for sludge and sediment, respectively. A demonstration of the method was performed by conducting a limited survey of domestic sludge and sediments. The concentration of PFCs in domestic sludge ranged from 5 to 152 ng/g for total perfluorocarboxylates and 55 to 3370 ng/g for total perfluoroalkyl sulfonyl-based chemicals. Data from a survey of San Francisco Bay Area sediments suggest widespread occurrence of PFCs in sediments at the low ng/g to sub-ng/g level. Furthermore, substances that may be transformed to PFOS, such as 2-(N-ethylperfluorooctanesulfonamido) acetic acid (N-EtFOSAA) and 2-(N-methylperfluorooctanesulfonamido) acetic acid (N-MeFOSAA), are present in both sediments and sludge at levels often exceeding PFOS.

    View details for DOI 10.1021/es048245p

    View details for Web of Science ID 000229662200019

    View details for PubMedID 15984769

  • The sequestration of PCBs in Lake Hartwell sediment with activated carbon WATER RESEARCH Werner, D., Higgins, C. P., Luthy, R. G. 2005; 39 (10): 2105-2113


    Recent laboratory studies with a marine sediment from a tidal mudflat in San Francisco Bay demonstrated that a low dose of activated carbon enhances the sequestration of PCBs and PAHs under well-mixed conditions. Here we compare activated carbon treatment for a freshwater sediment from a rural site, using PCB-contaminated sediment from Lake Hartwell, SC. An activated carbon dose of 2% of the dry sediment mass lowered total aqueous PCB concentrations by more than 95% after 1 month of treatment and more than 98% after 6 months. Aqueous PCB concentrations remained below detection limits following 18 months of sediment-carbon contact in slowly mixed systems. Uptake of PCBs into semipermeable membrane devices was reduced by 78%, 91% and 97% over 1, 6 and 18 months, respectively. These tests show that PCB sequestration with activated carbon improves with contact time and is not diminished by prolonged mixing with sediment. Desorption studies confirmed the sequestration, in which 74% of the total PCB mass could be desorbed from untreated Lake Hartwell sediment within 30 days as compared to only 7% after activated carbon treatment for 6 months. We compare these observations with marine sediment from San Francisco Bay and propose a conceptual model to rationalize how sediment properties relate to the reduction in aqueous PCB concentrations during activated carbon treatment.

    View details for DOI 10.1016/j.watres.2005.03.019

    View details for Web of Science ID 000230241200019

    View details for PubMedID 15922398

  • Addition of activated carbon to sediments to reduce PCB bioaccumulation by a polychaete (Neanthes arenaceodentata) and an amphipod (Leptocheirus plumulosus) ENVIRONMENTAL SCIENCE & TECHNOLOGY Millward, R. N., Bridges, T. S., Ghosh, U., Zimmerman, J. R., Luthy, R. G. 2005; 39 (8): 2880-2887


    This work examines the effects of adding coke or activated carbon on the bioavailability of polychlorinated biphenyls (PCBs) in contaminated sedimentfrom South Basin at Hunters Point, San Francisco Bay. We show with 28-day sediment exposure tests that PCB bioaccumulation in a polychaete (Neanthes arenaceodentata) is reduced by 82% following 1-month contact of sediment with activated carbon and by 87% following 6-months contact of sediment with activated carbon. PCB bioaccumulation in an amphipod (Leptocheirus plumulosus) is reduced by 70% following 1-month contact of sediment with activated carbon and by 75% after 6-months contact of sediment with activated carbon. Adding coke had a negligible effect on reducing PCB bioaccumulation, probably because of the low specific surface area and the slow kinetics of PCB diffusion intothe solid coke particles. Reductions in congener bioaccumulation with activated carbon were inversely related to congener Kow, suggesting that the efficacy of activated carbon is controlled by the mass-transfer rate of PCBs from sediment and into activated carbon. We find that reductions in aqueous PCB concentrations in equilibrium with the sediment were similar to reductions in PCB bioaccumulation. While no lethality was observed following activated carbon addition, growth rates were reduced by activated carbon for the polychaete, but not for the amphipod, suggesting the need for further study of the potential impacts of activated carbon on exposed communities. The study suggests that treatment of the biologically active layer of contaminated sediments with activated carbon may be a promising in-situ technique for reducing the bioavailability of sediment-associated PCBs and other hydrophobic organic compounds.

    View details for DOI 10.1021/es048768x

    View details for Web of Science ID 000228428900066

    View details for PubMedID 15884389

  • Soft x-ray spectromicroscopy study of carbonaceous materials: Characterization of their chemical heterogeneities in sub-micrometer scale Yoon, T. H., Benzerara, K., Ahn, S. W., Luthy, R. G., Tyliszczak, T., Brown, G. E. AMER CHEMICAL SOC. 2005: U860-U860
  • Response to comment on "Addition of carbon sorbents to reduce PCB and PAH: Bioavailability in marine sediments: Physicochemical tests" ENVIRONMENTAL SCIENCE & TECHNOLOGY Zimmerman, J. R., Luthy, R. G., Ghosh, U., Millward, R. N., Bridges, T. S. 2005; 39 (4): 1199-1200

    View details for DOI 10.1021/es047983a

    View details for Web of Science ID 000227001700039

  • Effect of oil on polychlorinated biphenyl phase partitioning during land biotreatment of impacted sediment JOURNAL OF ENVIRONMENTAL ENGINEERING-ASCE McNamara, S. W., Ghosh, U., Dzombak, D. A., Weber, A. S., Smith, J. R., Luthy, R. G. 2005; 131 (2): 278-286
  • Sorbent wicking device for sampling hydrophobic organic compounds in unsaturated soil pore water. I: Design and hydraulic characteristics JOURNAL OF ENVIRONMENTAL ENGINEERING-ASCE McNamara, S. W., Luthy, R. G. 2005; 131 (1): 11-20
  • Improving Risk Assessments for Manufactured Gas Plant Soils Integrated Environmental Assessment and Management Stroo, Hans, F., Nakles, David, V., Kreitinger, Joseph, P., Loehr, Raymond, C., Hawthorne, Steven, B., Luthy, Richard, G. 2005; 1 (3): 259-266
  • Sorbent wicking device for sampling hydrophobic organic compounds in unsaturated soil pore water. II: Chemical capture, recovery, and analysis JOURNAL OF ENVIRONMENTAL ENGINEERING-ASCE McNamara, S. W., Luthy, R. G. 2005; 131 (1): 21-28
  • Thermal program desorption mass spectrometry of PAHs from mineral and organic surfaces ENVIRONMENTAL ENGINEERING SCIENCE Talley, J. W., Ghosh, U., Furey, J. S., Tucker, S. G., Luthy, R. G. 2004; 21 (6): 647-660
  • Addition of carbon sorbents to reduce PCB and PAH bioavailability in marine sediments: Physicochemical tests ENVIRONMENTAL SCIENCE & TECHNOLOGY Zimmerman, J. R., Ghosh, U., Millward, R. N., Bridges, T. S., Luthy, R. G. 2004; 38 (20): 5458-5464


    The addition of activated carbon as particulate sorbent to the biologically active layer of contaminated sediment is proposed as an in-situ treatment method to reduce the chemical and biological availability of hydrophobic organic contaminants (HOCs) such as polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). We report results from physicochemical experiments that assess this concept. PCB- and PAH-contaminated sediment from Hunters Point Naval Shipyard, San Francisco Bay, CA, was contacted with coke and activated carbon for periods of 1 and 6 months. Sediment treated with 3.4 wt % activated carbon showed 92% and 84% reductions in aqueous equilibrium PCB and PAH concentrations, 77% and 83% reductions in PCB and PAH uptake by semipermeable membrane devices (SPMD), respectively, and reductions in PCB flux to overlying water in quiescent systems up to 89%. Adding coke to contaminated sediment did not significantly decrease aqueous equilibrium PCB concentrations nor PCB or PAH availability in SPMD measurements. Coke decreased PAH aqueous equilibrium concentrations by 38-64% depending on coke dose and particle size. The greater effectiveness of activated carbon as compared to coke is attributed to its much greater specific surface area and a pore structure favorable for binding contaminants. The results from the physicochemical tests suggest that adding activated carbon to contaminated field sediment reduces HOC availability to the aqueous phase. The benefit is manifested relatively quickly under optimum contact conditions and improves in effectiveness with contact time from 1 to 6 months. Activated carbon application is a potentially attractive method for in-situ, nonremoval treatment of marine sediment contaminated with HOCs.

    View details for DOI 10.1021/es034992v

    View details for Web of Science ID 000224519500034

    View details for PubMedID 15543751

  • Effects of particulate carbonaceous matter on the bioavailability of benzo[a]pyrene and 2,2 ',5,5 '-tetrachlorobiphenyl to the clam, Macoma balthica ENVIRONMENTAL SCIENCE & TECHNOLOGY McLeod, P. B., van den Heuvel-Greve, M. J., Allen-King, R. M., Luoma, S. N., Luthy, R. G. 2004; 38 (17): 4549-4556


    We investigated the bioavailability via diet of spiked benzo[a]pyrene (BaP) and 2,2',5,5'-tetrachlorobiphenyl (PCB-52) from different carbonaceous (non-carbonate, carbon containing) particle types to clams (Macoma balthica) collected from San Francisco Bay. Our results reveal significant differences in absorption efficiency between compounds and among carbonaceous particle types. Absorption efficiency for PCB-52 was always greater than that for BaP bound to a given particle type. Among particles, absorption efficiency was highest from wood and diatoms and lowest from activated carbon. Large differences in absorption efficiency could not be simply explained by comparatively small differences in the particles' total organic carbon content. BaP and PCB-52 bound to activated carbon exhibited less than 2% absorption efficiency and were up to 60 times less available to clams than the same contaminants associated with other types of carbonaceous matter. These results suggest that variations in the amount and type of sediment particulate carbonaceous matter, whether naturally occurring or added as an amendment, will have a strong influence on the bioavailability of hydrophobic organic contaminants. This has important implications for environmental risk assessment, sediment management, and development of novel remediation techniques.

    View details for DOI 10.1021/es049893b

    View details for Web of Science ID 000223678900021

    View details for PubMedID 15461162

  • Granular activated carbon treatment of contaminated sediment to reduce PCB availability and biouptake. McLeod, P. B., Zimmerman, J. R., Werner, D., Smithenry, D. W., Luthy, R. G. AMER CHEMICAL SOC. 2004: U618-U618
  • Microbial transformations of perfluorinated organics. Fu, Q. S., Rhoads, K. R., Higgins, C. P., Luthy, R. G., Criddle, C. S. AMER CHEMICAL SOC. 2004: U609-U609
  • Effects of thiocyanate on the formation of free cyanide during chlorination and ultraviolet disinfection of publicly owned treatment works secondary effluent WATER ENVIRONMENT RESEARCH Zheng, A. P., Dzombak, D. A., Luthy, R. G. 2004; 76 (3): 205-212


    Cyanide has been detected in effluent of some publicly owned treatment works (POTWs) at levels exceeding influent concentration. Thiocyanate (SCN-) is a cyanide-related compound encountered in most POTW influents and may be decomposed to free cyanide (CN-) under some circumstances. Effects of SCN- on the formation of cyanide during chlorination and UV disinfection were studied through a laboratory study with synthetic solutions and POTW secondary effluent. Results indicated that CN- was detected in SCN- solutions after chlorination in which the chlorine dose or reaction time was not sufficient to destroy SCN-completely, thus ensuring no residual chlorine to destroy any CN-produced. It was also found that SCN can be broken down to yield cyanide by UV irradiation. In addition, SCN- was observed to cause significant positive error in the conventional total cyanide analysis technique involving acidic distillation and colorimetric measurement when nitrate was present in the sample.

    View details for Web of Science ID 000222451500003

    View details for PubMedID 15338691

  • Effects of nitrosation on the formation of cyanide in publicly owned treatment works secondary effluent WATER ENVIRONMENT RESEARCH Zheng, A. P., Dzombak, D. A., Luthy, R. G. 2004; 76 (3): 197-204


    Cyanide has been detected in the effluents of some publicly owned treatment works (POTWs) at levels exceeding the influent concentration. The presence of nitrite ion (NO2-) as a common constituent in domestic wastewater effluents may play an important role in the formation of cyanide through reaction with certain kinds of organic compounds, especially aromatic compounds. Laboratory studies with seven organic compounds (aniline. p-toluidine, phenol, 1,2,4-trihydroxybenzene, L-serine, glycine, and benzoic acid) revealed that cyanide can be formed by reaction of nitrite with some of these compounds. The most substantial free cyanide (HCN. CN-) production observed at 25 degrees C was 0.15 mg/L from reaction of 0.01 mM 1.2.4-trihydroxybenze with 5 mg/L nitrite for 72 hours. Substantial free cyanide formation was also observed at pH 2-4 in experiments with POTW effluents when reactive organics and nitrite were both added to wastewater. Formation of cyanide through nitrosation was strongly pH dependent, being most significant at low pH (2 to 4) and negligible at neutral-to-high pH. This result points to nitrous acid (HNO2) as being more reactive than the dissociated NO2- ion. The reaction of these nitrite species with organics also occurs in conventional analyses for total cyanide which involve distillation under strongly acidic conditions. Sufficient sample pretreatment with sulfamic acid at the time of sampling, not at the time of analysis. is highly recommended to prevent biasing analytical measurement of total cyanide in POTW effluents.

    View details for Web of Science ID 000222451500002

    View details for PubMedID 15338690

  • Formation of free cyanide and cyanogen chloride from chloramination of publicly owned treatment works secondary effluent: Laboratory study with model compounds WATER ENVIRONMENT RESEARCH Zheng, A. P., Dzombak, D. A., Luthy, R. G. 2004; 76 (2): 113-120


    The potential generation of cyanide species in wastewater upon chlorination in the presence of residual ammonia (resulting in chloramine formation) was investigated in experiments with synthetic solutions and publicly owned treatment works (POTW) secondary effluent. This study demonstrated that low concentrations (approximately 5 to 25 microg/L as cyanide) of cyanogen chloride (CNCI), a highly toxic cyanide species not measured in total or free cyanide analyses, could be detected as a result of chloramination reactions in POTW secondary effluent. The potential for chloramination of nitrogen-bearing organic compounds to yield CNCl and/or free cyanide was demonstrated in experiments with synthetic solutions spiked with selected precursor organics: L-serine, benzene, catechin, and humic acid. The amino acid L-serine yielded the largest concentrations of CNCI upon chloramination. Additionally, detectable cyanide (approximately 10 microg/L) was observed in solutions of L-serine and in POTW secondary effluent that was chloraminated followed by dechlorination to prevent destruction of any free cyanide produced. Thus, chlorination of POTW secondary effluent containing residual ammonia can lead to chloramination of organic compounds and the resulting production of CNCl and free cyanide.

    View details for Web of Science ID 000221290800004

    View details for PubMedID 15168842

  • The occurrence of cyanide formation in six full-scale publicly owned treatment works WATER ENVIRONMENT RESEARCH Zheng, A. P., Dzombak, D. A., Luthy, R. G., Kavanaugh, M. C., Deeb, R. A. 2004; 76 (2): 101-112


    This paper presents results from an intensive monitoring program implemented at six full-scale publicly owned treatment works (POTWs) to investigate the fate and formation of cyanide in wastewater treatment processes, with a focus on chlorination and dechlorination processes. A review of historical monitoring data for cyanide species in these POTWs was also conducted. This POTW monitoring program provided a database for the investigation of cyanide formation in wastewater secondary treatment. Data from participating POTWs showed evidence of cyanide formation in this 1-year monitoring effort, although the cyanide formation pattern varied significantly from one plant to another and among seasons. Generally, the chlorination of thiocyanate (SCN-) seems to be the most important mechanism for the formation of cyanide in wastewater treatment processes, especially in chlorination and dechlorination. This hypothesis is supported by the findings of a related laboratory study of mechanisms of cyanide formation in POTWs. It is recommended that POTWs monitor SCN in influent and secondary effluent to identify its presence and adjust chlorine dose appropriately.

    View details for Web of Science ID 000221290800003

    View details for PubMedID 15168841

  • Release of polychlorinated to water under biphenyls from river sediment low-flow conditions: Laboratory assessment. JOURNAL OF ENVIRONMENTAL ENGINEERING-ASCE Ortiz, E., Luthy, R. G., Dzombak, D. A., Smith, J. R. 2004; 130 (2): 126-135
  • Microscale association of organic contaminants to sediment particles and implications for risk management. Ghosh, U., Zimmerman, J. R., McLeod, P. B., Luthy, R. G., Milward, R. N., Bridges, T. S. AMER CHEMICAL SOC. 2003: U514-U514
  • PAH sorption mechanism and partitioning behavior in lampblack-impacted soils from former oil-gas plant sites ENVIRONMENTAL SCIENCE & TECHNOLOGY Hong, L., Ghosh, U., Mahajan, T., Zare, R. N., Luthy, R. G. 2003; 37 (16): 3625-3634


    This study assessed polycyclic aromatic hydrocarbon (PAH) association and aqueous partitioning in lampblack-impacted field soils from five sites in California that formerly housed oil-gas process operations. Lampblack is the solid residue resulting from the decomposition of crude oil at high temperatures in the gas-making operation and is coated or impregnated with oil gasification byproducts, among which PAHs are the compounds of the greatest regulatory concern. A suite of complementary measurements investigated the character of lampblack particles and PAH location and the associated effects on PAH partitioning between lampblack and water. PAH analyses on both whole samples and density-separated components demonstrated that 81-100% of PAHs in the lampblack-impacted soils was associated with lampblack particles. FTIR, 13C NMR, and SEM analyses showed that oil-gas lampblack solids comprise primarily aromatic carbon with soot-like structures. A free-phase aromatic oil may be present in some of the lampblack soils containing high PAH concentrations. Comparable long-term aqueous partitioning measurements were obtained with an air-bridge technique and with a centrifugation/alum flocculation procedure. Large solid/water partition coefficient (Kd) values were observed in samples exhibiting lower PAH and oil levels, whereas smaller Kd values were measured in lampblack samples containing high PAH levels. The former result is in agreement with an oil-soot partitioning model, and the latter is in agreement with a coal tar-water partitioning model. Lampblack containing high PAH levels appears to exhaust the sorption capacity of the soot-carbon, creating a free aromatic oil phase that exhibits partitioning behavior similar to PAHs in coal tar. This study improves mechanistic understanding of PAH sorption on aged lampblack residuals at former oil-gas sites and provides a framework for mechanistic assessment of PAH leaching potential and risk from such site materials.

    View details for DOI 10.1021/es0262683

    View details for Web of Science ID 000184803700022

    View details for PubMedID 12953875

  • Contaminant bioavailability in soil and sediment ENVIRONMENTAL SCIENCE & TECHNOLOGY Ehlers, L. J., Luthy, R. G. 2003; 37 (15): 295A-302A

    View details for Web of Science ID 000184501900023

    View details for PubMedID 12966964

  • PCB and PAH speciation among particle types in contaminated harbor sediments and effects on PAH bioavailability ENVIRONMENTAL SCIENCE & TECHNOLOGY Ghosh, U., Zimmerman, J. R., Luthy, R. G. 2003; 37 (10): 2209-2217


    This research provides particle-scale understanding of PCB and PAH distribution in sediments obtained from three urban locations in the United States: Hunters Point, CA; Milwaukee Harbor, WI; and Harbor Point, NY. The sediments comprised mineral grains (primarily sand, silt, and clays) and carbonaceous particles (primarily coal, coke, charcoal, pitch, cenospheres, and wood). The carbonaceous sediment fractions were separated from the mineral fractions based on their lower density and were identified by petrographic analysis. In all three sediments, carbonaceous particles contributed 5-7% of the total mass and 60-90% of the PCBs and PAHs. The production of carbonaceous particles is not known to be associated with PCB contamination, and it is very unlikely that these particles can be the source of PCBs in the environment Thus, it appears that carbonaceous particles preferentially accumulate PCBs acting as sorbents in the aqueous environment if PCBs are released directly to the sediment or if deposited as airborne soot particles. Aerobic bioslurry treatment resulted in negligible PAH loss from the carbonaceous coal-derived material in Milwaukee Harbor sediment but resulted in 80% of the PAHs being removed from carbonaceous particles in Harbor Point sediment. Microscale PAH extraction and analysis revealed that PAHs in Harbor Point sediment were associated mainly with coal tar pitch residue. PAHs present in semisolid coal tar pitch are more bioavailable than PAHs sorbed on carbonaceous particles such as coal, coke, charcoal, and cenosphere. Results of this study illustrate the importance of understanding particle-scale association of hydrophobic organic contaminants for explaining bioavailability differences among sediments.

    View details for DOI 10.1021/es020833k

    View details for Web of Science ID 000182866000025

    View details for PubMedID 12785527

  • Evaluation and testing of analytical methods for cyanide species in municipal and industrial contaminated waters ENVIRONMENTAL SCIENCE & TECHNOLOGY Zheng, A. P., Dzombak, D. A., Luthy, R. G., Sawyer, B., Lazouskas, W., Tata, P., Delaney, M. F., Zilitinkevitch, L., Sebroski, J. R., Swartling, R. S., Drop, S. M., Flaherty, J. M. 2003; 37 (1): 107-115


    Total cyanide analysis by distillation is used most commonly to assess cyanide content of water samples. This manual method is robust but slow and provides no information about cyanide speciation, a significant limitation in that cyanide species have substantially different toxicity characteristics. Seven alternative methods for the analysis of cyanide species or groups of species were evaluated in reagent water and five different contaminated water matrices, including five species-specific methods--weak acid dissociable (WAD) cyanide, free cyanide by microdiffusion, available cyanide, automated WAD cyanide by thin film distillation, metal cyanides by ion chromatography--and two automated techniques for total cyanide--total cyanide bythin film distillation and total cyanide by low-power UV digestion. The species-specific cyanide analytical techniques achieved low, ppb-level detection limits and exhibited satisfactory accuracy and precision for most contaminated waters. Analysis of low concentrations of cyanide species in raw wastewater was problematical for the available cyanide and ion chromatography methods, which experienced significant interference problems and/or low recoveries. There was recovery of significant diffusible cyanide in microdiffusion tests with nickel-cyanide-spiked samples, reflecting dissociation of this weak metal-cyanide complex during the test and demonstrating that the test can recover some fraction of WAD cyanide in addition to free cyanide. The automated total cyanide methods, which involve UV digestion, achieved low detection limits for most waters but exhibited low recoveries for some waters.

    View details for DOI 10.1021/es0258273

    View details for Web of Science ID 000180246200033

    View details for PubMedID 12542298

  • Bioterrorism and water security ENVIRONMENTAL SCIENCE & TECHNOLOGY Luthy, R. G. 2002; 36 (7): 123A-123A

    View details for Web of Science ID 000174789200002

    View details for PubMedID 11999032

  • Particle-scale understanding of the bioavailability of PAHs in sediment ENVIRONMENTAL SCIENCE & TECHNOLOGY Talley, J. W., Ghosh, U., Tucker, S. G., Furey, J. S., Luthy, R. G. 2002; 36 (3): 477-483


    This study reports results of sediment bioslurry treatment and earthworm bioaccumulation for polycyclic aromatic hydrocarbon (PAH) contaminants found in sediment dredged from Milwaukee Harbor. A significant finding was that bioslurry treatment reduced PAHs on the sediment clay/silt fraction but not on the sediment coal-derived fraction and that PAH reduction in the clay/silt fraction correlated with substantial reduction in earthworm PAH bioaccumulation. These findings are used to infer PAH bioavailability from characterization of particle-scale PAH distribution, association, and binding among the principal particle fractions in the sediment. The results are consistent with work showing that the sediment comprised two principal particle classes for PAHs, coal-derived and clay/silt, each having much different PAH levels, release rates, and desorption activation energies. PAH sorption on coal-derived particles is associated with minimal biodegradation, slow release rates, and high desorption activation energies, while PAH sorption on clay/silt particles is associated with significant potential biodegradability, relatively fast release rates, and lower desorption activation energies. These characteristics are attributed to fundamental differences in the organic matter to which the PAHs are sorbed. Although the majority of the PAHs are found preferentially on coal-derived particles, the PAHs on the clay/silt sediment fraction are more mobile and available, and thus potentially of greater concern. This study demonstrates that a suite of tests comprising both bioassays and particle-scale investigations provide a basis to assess larger-scale phenomena of biotreatment of PAH-impacted sediments and bioavailability and potential toxicity of PAH contaminants in sediments. Improved understanding of contaminant bioavailability aids decision-making on the effectiveness of biotreatment of PAH-impacted sediments and the likelihood for possible reuse of dredged sediments as reclaimed soil or fill.

    View details for DOI 10.1021/es010897f

    View details for Web of Science ID 000173626900041

    View details for PubMedID 11871564

  • Microscale detection of polychlorinated biphenyls using two-step laser mass spectrometry INTERNATIONAL JOURNAL OF MASS SPECTROMETRY Mahajan, T. B., Ghosh, U., Zare, R. N., Luthy, R. G. 2001; 212 (1-3): 41-48
  • Particle-scale investigation of PAH desorption kinetics and thermodynamics from sediment ENVIRONMENTAL SCIENCE & TECHNOLOGY Ghosh, U., Talley, J. W., Luthy, R. G. 2001; 35 (17): 3468-3475


    Dredged sediment from Milwaukee Harbor showed two primary classes of particles in the <2 mm size range: a lighter-density coal- and wood-derived fraction with 62% of total PAHs and a heavier-density sand, silt, and clay fraction containing the remaining 38% of the PAHs. Room-temperature PAH desorption kinetic studies on separated sediment fractions revealed slow desorption rates for the coal-derived particles and fast desorption rates for the clay/silt particles. The effect of temperature on PAH release was measured by thermal program desorption mass spectrometry to investigate the desorption activation energies for PAHs on the different sediment particles. Three activated diffusion-based models and an activated first-order rate model were used to describe the thermal desorption of PAHs for four molecular weight classes. PAH binding with the coal-derived particles was associated with high activation energies, typically in the range of 115-139 kJ/mol. PAHs bound to the clay/silt material had much lower activation energy, i.e., in the range of 37-41 kJ/ mol for molecular weight 202. Among the desorption models tested, a spherical diffusion model with PAHs located like a rind on the outer 1-3 microm region best described the PAH thermal desorption response for coal-derived particles. This internal PAH distribution pattern on coalderived particles is based on prior direct measurement of PAH locations at the subparticle scale. These studies reveal that heterogeneous particle types in sediment exhibit much different amounts and binding of PAHs. PAHs associated with coal-derived particles aged over several decades in the field appear to be far from reaching an equilibrium sorption state due to the extremely slow diffusivities through the polymer-like coal matrix. These results provide an improved mechanistic perspective for the understanding of PAH mobility and bioavailability in sediments.

    View details for DOI 10.1021/es0105820

    View details for Web of Science ID 000170824300021

    View details for PubMedID 11563648

  • Succession of phenotypic, genotypic, and metabolic community characteristics during in vitro bioslurry treatment of polycyclic aromatic hydrocarbon-contaminated sediments APPLIED AND ENVIRONMENTAL MICROBIOLOGY Ringelberg, D. B., Talley, J. W., Perkins, E. J., Tucker, S. G., Luthy, R. G., Bouwer, E. J., Fredrickson, H. L. 2001; 67 (4): 1542-1550


    Dredged harbor sediment contaminated with polycyclic aromatic hydrocarbons (PAHs) was removed from the Milwaukee Confined Disposal Facility and examined for in situ biodegradative capacity. Molecular techniques were used to determine the successional characteristics of the indigenous microbiota during a 4-month bioslurry evaluation. Ester-linked phospholipid fatty acids (PLFA), multiplex PCR of targeted genes, and radiorespirometry techniques were used to define in situ microbial phenotypic, genotypic, and metabolic responses, respectively. Soxhlet extractions revealed a loss in total PAH concentrations of 52%. Individual PAHs showed reductions as great as 75% (i.e., acenapthene and fluorene). Rates of (14)C-PAH mineralization (percent/day) were greatest for phenanthrene, followed by pyrene and then chrysene. There was no mineralization capacity for benzo[a]pyrene. Ester-linked phospholipid fatty acid analysis revealed a threefold increase in total microbial biomass and a dynamic microbial community composition that showed a strong correlation with observed changes in the PAH chemistry (canonical r(2) of 0.999). Nucleic acid analyses showed copies of genes encoding PAH-degrading enzymes (extradiol dioxygenases, hydroxylases, and meta-cleavage enzymes) to increase by as much as 4 orders of magnitude. Shifts in gene copy numbers showed strong correlations with shifts in specific subsets of the extant microbial community. Specifically, declines in the concentrations of three-ring PAH moieties (i.e., phenanthrene) correlated with PLFA indicative of certain gram-negative bacteria (i.e., Rhodococcus spp. and/or actinomycetes) and genes encoding for naphthalene-, biphenyl-, and catechol-2,3-dioxygenase degradative enzymes. The results of this study suggest that the intrinsic biodegradative potential of an environmental site can be derived from the polyphasic characterization of the in situ microbial community.

    View details for Web of Science ID 000167865500022

    View details for PubMedID 11282603

  • Microprobe laser mass spectrometry studies of polycyclic aromatic hydrocarbon distributions on harbor sediments and coals ISRAEL JOURNAL OF CHEMISTRY Gillette, J. S., Ghosh, U., Mahajan, T. B., Zare, R. N., Luthy, R. G. 2001; 41 (2): 105-110
  • Microscale PAH location ano association with organic matter and effects on biotreatment and bioaccumulation. Luthy, R. G., Ghosh, U., Gillette, J. S., Zare, R. N., Talley, J. W., Tucker, S. AMER CHEMICAL SOC. 2000: U337-U337
  • Microscale location, characterization, and association of polycyclic aromatic hydrocarbons on harbor sediment particles ENVIRONMENTAL SCIENCE & TECHNOLOGY Ghosh, U., Gillette, J. S., Luthy, R. G., Zare, R. N. 2000; 34 (9): 1729-1736
  • Theoretical study of hydrogen abstraction from ethane by small radicals. Senosiain, J. P., Musgrave, C. B., GOLDEN, D. M. AMER CHEMICAL SOC. 2000: U325-U325
  • Direct observation of polycyclic aromatic hydrocarbons on geosorbents at the subparticle scale ENVIRONMENTAL SCIENCE & TECHNOLOGY Gillette, J. S., Luthy, R. G., Clemett, S. J., Zare, R. N. 1999; 33 (8): 1185-1192
  • Organic phase resistance to dissolution of polycyclic aromatic hydrocarbon compounds ENVIRONMENTAL SCIENCE & TECHNOLOGY ORTIZ, E., Kraatz, M., Luthy, R. G. 1999; 33 (2): 235-242
  • Organic Phase Resistance to Dissolution of Polycyclic Aromatic Hydrocarbon Compounds Environmental Science and Technology Ortiz, E., Kraatz, M., Luthy, R., G. 1999; 2 (33): 235-242
  • Equilibrium precipitation and dissolution of iron cyanide solids in water ENVIRONMENTAL ENGINEERING SCIENCE Ghosh, R. S., Dzombak, D. A., Luthy, R. G. 1999; 16 (4): 293-313
  • Equilibrium Precipitation and Dissolution of Iron Cyanide Solids in Water Environmental Engineering Science Ghosh, R., S., Dzombak, D., A., Luthy, R., G. 1999; 16: 293-313
  • In situ measurement of PCB availability in unsaturated soils BIOREMEDIATION OF NITROAROMATIC AND HALOAROMATIC COMPOUNDS McNamara, S., Luthy, R. G. 1999: 241-246
  • Biodegradation kinetics of naphthalene in nonaqueous phase liquid-water mixed batch systems: Comparison of model predictions and experimental results BIOTECHNOLOGY AND BIOENGINEERING Ghoshal, S., Luthy, R. G. 1998; 57 (3): 356-366


    A model is formulated to describe dissolution of naphthalene from an insoluble nonaqueous phase liquid (NAPL) and its subsequent biodegradation in the aqueous phase in completely mixed batch reactors. The physicochemical processes of equilibrium partitioning and mass transfer of naphthalene between the NAPL and aqueous phases were incorporated into the model. Biodegradation kinetics were described by Monod's microbial growth kinetic model, modified to account for the inhibitory effects of 1,2-naphthoquinone formed during naphthalene degradation under certain conditions. System parameters and biokinetic coefficients pertinent to the NAPL-water systems were determined either by direct measurement or from nonlinear regression of the naphthalene mineralization profiles obtained from batch reactor tests with two-component NAPLs comprised of naphthalene and heptamethylnonane. The NAPLs contained substantial mass of naphthalene, and naphthalene biodegradation kinetics were evaluated over the time required for near complete depletion of naphthalene from the NAPL. Model predictions of naphthalene mineralization time profiles compared favorably to the general trends observed in the data obtained from laboratory experiments with the two-component NAPL, as well as with two coal tars obtained from the subsurface at contaminated sites and composed of many different PAHs (polycyclic aromatic hydrocarbon compounds). The effects of varying the NAPL mass and the naphthalene mole fractions in the NAPL are discussed. It was observed that the time to achieve a given percent removal of naphthalene does not change significantly with the initial mass of naphthalene in a fixed volume of the NAPL. Significant changes in the mineralization profiles are observed when the volume (and mass) of NAPL in the system is changed.

    View details for Web of Science ID 000070987000012

    View details for PubMedID 10099212

  • Sequestration of hydrophobic organic contaminants by geosorbents ENVIRONMENTAL SCIENCE & TECHNOLOGY Luthy, R. G., Aiken, G. R., Brusseau, M. L., Cunningham, S. D., Gschwend, P. M., Pignatello, J. J., Reinhard, M., Traina, S. J., Weber, W. J., Westall, J. C. 1997; 31 (12): 3341-3347
  • Mass transfer and bioavailability of PAH compounds in coal tar NAPL-slurry systems .1. Model development ENVIRONMENTAL SCIENCE & TECHNOLOGY Ramaswami, A., Luthy, R. G. 1997; 31 (8): 2260-2267
  • Mass transfer and bioavailability of PAH compounds in coal tar NAPL-slurry systems .2. Experimental evaluations ENVIRONMENTAL SCIENCE & TECHNOLOGY Ramaswami, A., Ghoshal, S., Luthy, R. G. 1997; 31 (8): 2268-2276
  • Dissolution of PCB congeners from an Aroclor and an Aroclor/hydraulic oil mixture WATER RESEARCH Luthy, R. G., Dzombak, D. A., SHANNON, M. J., UNTERMAN, R., Smith, J. R. 1997; 31 (3): 561-573
  • Aqueous Solubility of PCB Congeners from an Aroclor and an Aroclor/Hydraulic Oil Mixture Water Research Luthy, R., G., Dzombak, D., A., Shannon, M., J.R., Unterman, R., Smith, J., R. 1997; 3 (31): 561-573
  • PAH-bioavailability from NAPLs and significance for soil biotreatment IN SITU AND ON-SITE BIOREMEDIATION, VOL 5 Kraatz, M., ORTIZ, E., Luthy, R. G. 1997; 4(5): 669-674
  • Measuring and Modeling Physico-Chemical Limitations to Bioavailability and Biodegradation, Chapter 78 Manual of Environmental Microbiology Adeel, Z., Luthy, R., G. edited by Sabatini, D., A., Knox, R., C., Harwell, J., H. American Society for Microbiology, ASM Press Washington, DC.. 1997
  • Measuring and Modeling Physico-Chemical Limitations to Bioavailability and Biodegradation Manual of Environmental Microbiology Laha, S. edited by Huang, C., P., O’Melia, C., R., Morgan, J., J. American Society for Microbiology, ASM Press Washington, DC.. 1997: 339-362
  • Mass Transfer and Bioavailability of PAH Compounds in Coal Tar NAPL-Slurry Systems: 2. Experimental Evaluations Environmental Science and Technology Ramaswami, A., Ghoshal, S., Luthy, R., G. 1997; 8 (31): 2268-2276
  • Mass Transfer and Bioavailability of PAH Compounds in Coal Tar NAPL-Slurry Systems: 1. Model Development Environmental Science and Technology Ramaswami, A., Luthy, R., G. 1997; 8 (31): 2260-2267
  • Bioavailability of hydrophobic organic compounds from nonaqueous-phase liquids: The biodegradation of naphthalene from coal tar ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY Ghoshal, S., Luthy, R. G. 1996; 15 (11): 1894-1900
  • Biodegradation of naphthalene from coal tar and heptamethylnonane in mixed batch systems ENVIRONMENTAL SCIENCE & TECHNOLOGY Ghoshal, S., Ramaswami, A., Luthy, R. G. 1996; 30 (4): 1282-1291
  • Chemical characterization of coal tar-water interfacial films ENVIRONMENTAL SCIENCE & TECHNOLOGY Nelson, E. C., Ghoshal, S., Edwards, J. C., Marsh, G. X., Luthy, R. G. 1996; 30 (3): 1014-1022
  • Biodegradation of Naphthalene from Coal Tar and Heptamethylnonane in Mixed Batch Systems Environmental Science and Technology Ghoshal, S., Ramaswami, A., Luthy, R., G. 1996; 30 (4): 1282-1291
  • Chemical Characterization of Coal Tar-Water Interfacial Films Environmental Science and Technology Nelson, E., C., Ghoshal, S., Edwards, J., C., Marsh, G., X., Luthy, R., G. 1996; 30 (3): 1014-1022
  • Bioavailability of Hydrophobic Organic Compounds from Nonaqueous Phase Liquids: The Biodegradation of Naphthalene from Coal Tar Environmental Toxicology and Chemistry Goshal, S., Luthy, R., G. 1996; 15 (11): 1894-1990

    View details for Web of Science ID A1995QP70900035

    View details for PubMedID 22176412

  • Modeling Transport of Multiple Organic Compounds: Segregated Transport-Sorption/Solubilization Numerical Technique Water Resources Research Adeel, Z., Luthy, R., G., Edwards, D., A. 1995; 31 (8): 2035-2045


    The principal objective of this study was to quantify the bioavailability of micelle-solubilized naphthalene to naphthalene-degrading microorganisms comprising a mixed population isolated from contaminated waste and soils. Two nonionic surfactants were used, an alkylethoxylate, Brij 30 (C12E4), and an alkylphenol ethoxylate, Triton X-100 (C8PE9.5). Batch experiments were used to evaluate the effects of aqueous, micellized nonionic surfactants on the microbial mineralization of naphthalene and salicylic acid, an intermediate compound formed in the pathway of microbial degradation of naphthalene. The extent of solubilization and biodegradation under aerobic conditions was monitored by radiotracer and spectrophotometric techniques. Experimental results showed that surfactant concentrations above the critical micelle concentration were not toxic to the naphthalene-degrading bacteria and that the presence of surfactant micelles did not inhibit mineralization of naphthalene. Naphthalene solubilized by micelles of Brij 30 or Triton X-100 in liquid media was bioavailable and degradable by the mixed culture of bacteria.

    View details for Web of Science ID A1995PY86700024

    View details for PubMedID 7887597

  • Biodegradation of naphthalene from nonaqueous-phase liquids MICROBIAL PROCESSES FOR BIOREMEDIATION Ghoshal, S., Ramaswami, A., Luthy, R. G. 1995; 3 (8): 75-82
  • Biodegradation of naphthalene from coal tar: An assessment of the potential for slurry treatment at MGP sites INNOVATIVE TECHNOLOGIES FOR SITE REMEDIATION AND HAZARDOUS WASTE MANAGEMENT Ghoshal, S., Luthy, R. G. 1995: 211-218
  • Concentration-Dependent Regimes in Sorption and Transport of a Nonionic Surfactant in Sand/Aqueous Systems Surfactant-Enhanced Remediation and Subsurface Contamination: Emerging Technologies Emerging Technologies Ramaswami, A., Luthy, R., G. edited by Hurst, C., J. American Chemical Society Symposium. 1995: 712-729
  • Concentration-Dependent Regimes in Sorption and Transport of a Nonionic Surfactant in Sand/Aqueous Systems Adeel, A., Luthy, R., G. edited by Sabatini, D., A., Knox, R., C., Harwell, J., H. 1995
  • Surfactant Solubilization of Phenanthrene in Soil-Aqueous Systems and Its Effect on Biomineralization Aquatic Chemistry: Interfacial and Interspecies Processes Ramaswami, A., Luthy, R., G. edited by Hurst, C., J. American Chemical Society, Advances in Chemistry. 1995: 712-729
  • Biodegradation of Naphthalene in Aqueous Nonionic Surfactant Systems Applied and Environmental Microbiology Liu, Z., Jacobson, A., M., Luthy, R., G. 1995; 61 (1): 145-151

    View details for Web of Science ID A1994PA22100032

    View details for PubMedID 22165943


    View details for Web of Science ID A1994NU80800024

    View details for PubMedID 22176327

  • REMEDIATING TAR-CONTAMINATED SOILS AT MANUFACTURED-GAS PLANT SITES ENVIRONMENTAL SCIENCE & TECHNOLOGY Luthy, R. G., Dzombak, D. A., Peters, C. A., Roy, S. B., Ramaswami, A., Nakles, D. V., Nott, B. R. 1994; 28 (6): A266-A276
  • Additions and corrections: interfacial films in coal tar nonaqueous-phase liquid-water systems. Environmental science & technology Luthy, R. G., Ramaswami, A., Ghoshal, S., Merkel, W. 1994; 28 (4): 756-?

    View details for DOI 10.1021/es00053a600

    View details for PubMedID 22196563

  • Experimental Data and Modeling for Surfactant Micelles, HOCs and Soil Journal of Environmental Engineering, ASCE. Edwards, D., A., Liu, Z., Luthy, R., G. 1994; 120 (1): 23-41
  • Surfactant-Enhanced Bioremediation of Polynuclear Aromatic Hydrocarbons in Coke Waste Handbook of Bioremediation Sanseverino, J., Graves, D., A., Leavitt, M., E., Gupta, S., K., Luthy, R., G. edited by Wise, D., L., Trantolo, D., J. Marcel-Dekker, NY. 1994: 345-372
  • Mass Transfer and Biodegradation of PAH Compounds from Coal Tar Water Science and Technology Ramaswami, A., Ghoshal, S., Luthy, R., G. 1994; 30 (7): 61-70
  • Semiempirical Thermodynamic Modeling of Liquid-Liquid Phase Equilibria Coal Tar Dissolution in Water-Miscible Solvents Environmental Science and Technology Peters, C., A., Luthy, R., G. 1994; 28 (7): 1331-1340
  • Semi-Continuous Evaporation Model for Leachate Treatment Process Evaluation Environmental Progress Marks, A., L., Luthy, R., G., Diwekar, U., M. 1994; 13 (4): 278-289
  • Surfactant Solubilization of Organic Compounds in Soil/Aqueous Systems Journal of Environmental Engineering, ASCE. Edwards, D., A., Liu, Z., Luthy, R., G. 1994; 120 (1): 5-22
  • Landfill Leachate Treatment by Evaporation Journal of Environmental Engineering, ASCE Birchler, D., R., Milke, M., W., Marks, A., L., Luthy, R., G. 1994; 120 (5): 1109-1131
  • Distribution of Nonionic Surfactant and Phenanthrene in Sediment/Aqueous Systems Environmental Science and Technology Edwards, D., A., Adeel, Z., Luthy, R., G. 1994; 28 (8): 1550-1560
  • Remediating Tar-Contaminated Soils at Manufactured Gas Plant Sites Environmental Science and Technology Luthy, R., R., Dzombak, D., A., Peters, C., A., Roy, S., B., Ramaswami, A., Nakles, D., V. 1994; 28 (6): 266A-276A
  • Coal Tar Solubilization in Water-Miscible Solvents: Experimental Data Environmental Science and Technology Peters, C., A., Luthy, R., G. 1993; 27 (13): 2831-2843
  • Interfacial Films in Coal Tar Nonaqueous-Phase Liquid-Water Systems Environmental Science and Technology Luthy, R., G., Ramaswami, A., Ghoshal, S., Merkel, W. 1993; 27 (13): 2914-2918


    The solubilization and mineralization of (14)C-phenanthrene in soil-water systems was examined with several commercially available surface-active agents, viz., an alkyl ethoxylate C(12)E(4); two alkylphenol ethoxylate surfactants: C(8)PE(9.5) and C(9)PE(10.5); two sorbitan ethoxylate surfactants: the sorbitan monolaurate (Tween 20) and the sorbitan monooleate (Tween 80); two pairs of nonionic ethoxylate surfactant mixtures: C(12)E(4)/C(12)E(23) at a 1:1 ratio, and C(12-15)E(3)/C(12-15)E(9) at a 1:3 ratio; and two surfactants possessing relatively high critical micelle concentration (CMC) values and low aggregation numbers: CHAPS and octyglucoside. Surface tension experiments were performed to evaluate surfactant sorption onto soil and the surfactant doses required to attain the CMC in the soil-water systems. Surfactant solubilization of (14)C-phenanthrene commenced with the onset of micellization. The addition of surface-active agents was observed not to be beneficial to the microbial mineralization of phenanthrene in the soil-water systems and, for supra-CMC surfactant doses, phenanthrene mineralization was completely inhibited for all the surfactants tested. A comparison of solubilization, surface tension, and mineralization data confirms that the inhibitory effect on microbial degradation of phenanthrene is related to the CMC of the surfactant in the presence of soil. Additional tests demonstrated the recovery of mineralization upon dilution of surfactant concentration to sub-CMC levels, and a relatively high exit rate for phenanthrene from micelles. These tests suggest that the inhibitory effect is probably related to a reversible physiological surfactant micelle-bacteria interaction, possibly through partial complexing or release of membrane material with disrupting membrane lamellar structure. This study indicates that nonionic surfactant solubilization of sorbed hydrophobic organic compounds from soil may not be beneficial for the concomitant enhancement of soil bioremediation. Additional work is needed to address physicochemical processes for bioavailability enhancement, and effects of solubilizing agents on microorganisms for remediation and treatment of hydrophobic organic compounds and nonaqueous phase liquids.

    View details for Web of Science ID A1992JY04600010

    View details for PubMedID 18601093

  • SORPTION OF NONIONIC SURFACTANTS ONTO SOIL WATER RESEARCH Liu, Z. B., Edwards, D. A., Luthy, R. G. 1992; 26 (10): 1337-1345
  • Future Concerns in Environmental Engineering Graduate Education Journal of Professional Issues in Engineering Education and Practice, ASCE Luthy, R., G., Bella, D., A., Hunt, J., R., Johnson Jr., J., H., Lawler, D., F., O'Melia, C., R. 1992; 118 (4): 361-380
  • NONIONIC SURFACTANT SORPTION ONTO SOIL WATER SCIENCE AND TECHNOLOGY Liu, Z., Edwards, D. A., Luthy, R. G. 1992; 26 (9-11): 2337-2340
  • Effects of Nonionic Surfactants on the Solubilization and Mineralization of Phenanthrene in Soil-Water Systems Biotechnology and Bioengineering Laha, S., Luthy, R., G. 1992; 40 (11): 1367-1380
  • Interactions Between Nonionic Surfactant Monomers, Hydrophobic Organic Compounds and Soil Water Science and Technology Edwards, D., A., Liu, Z., Luthy, R., G. 1992; 26 (1-2): 147-158
  • Sorption of Nonionic Surfactants onto Soil Water Research Liu, Z., Edwards, D., A., Luthy, R., G. 1992; 26 (10): 1337-1345
  • Solubilization and Biodegradation of Hydrophobic Organic Compounds in Soil-Aqueous Systems with Nonionic Surfactants American Chemical Society Symposium Series No. 491, Transport and Remediation of Subsurface Contaminants: Colloidal, Interfacial and Surfactant Phenomena Sanseverino, J., Graves, D., A., Leavitt, M., E., Gupta, S., K., Luthy, R., G. edited by Wise, D., L., Trantolo, D., J. 1992: 345-372
  • Inhibition of Mineralization of Phenanthrene in Soil-Water Systems with Nonionic Surfactants Environmental Science and Technology Laha, S., Luthy, R., G. 1991; 25 (11): 1920-1930
  • Surfactant Solubilization of Polycyclic Aromatic Hydrocarbon Compounds in Soil-Water Suspensions Water Science and Technology Liu, Z., Laha, S., Luthy, R., G. 1991; 23: 475-485
  • Surfactant Enhanced Solubility of Hydrophobic Organic Compounds in Water and in Soil-Water Systems Organic Substances and Sediments in Water Edwards, D., A., Liu, Z., Luthy, R., G. edited by Baker, R., A. Lewis Publishers. 1991: 383-405
  • Bioremediation--Promises and Problems Editorial, Research Journal Water Pollution Control Federation Luthy, R., G. 1991; 63 (2)
  • Solubilization of Polycyclic Aromatic Hydrocarbons in Micellar Nonionic Surfactant Solutions Environmental Science and Technology Edwards, D., A., Luthy, R., G., Liu, Z. 1991; 25 (1): 127-133
  • Solving Groundwater Contamination Problems through Graduate Education in Environmental Engineering Water Environment and Technology Luthy, R., G., Benjamin, M., M. 1990; 2 (1): 48-57
  • Environmental Research: A Clearer Focus Across a Broader Horizon Environmental Science and Technology Luthy, R., G., Small, M., J. 1990; 24 (11): 1620-1623
  • Oxidation of Aniline and Other Primary Aromatic Amines by Manganese Dioxide Environmental Science and Technology Laha, S., Luthy, R., G. 1990; 24 (3): 363-373
  • Personnel and Research Shortages: Policy Recommendations for the Environmental Professions Environment Luthy, R., G. 1989; 31 (3): 4
  • Destruction of Iron-Complexed Cyanide by Alkaline Hydrolysis Water Science and Technology Robuck, S., J., Luthy, R., G. 1989; 21: 547-558
  • Microbial Degradation of Acenaphthene and Naphthalene Under Denitrification Conditions in Soil-Water Systems Applied and Environmental Microbiology Mihelcic, J., R., Luthy, R., G. 1988; 54: 1188-1198
  • Biodegradation Kinetics of Naphthalene in Nonaqueous Phase Liquid-Water Mixed Batch Systems: Comparison of Model Predictions and Experimental Results Biotechnology and Bioengineering Ghoshal, S., Luthy, R., G. 1988; 57 (3): 356-366
  • Degradation of Polycyclic Aromatic Hydrocarbon Compounds Under Various Redox Conditions in Soil-Water Systems Applied and Environmental Microbiology Mihelcic, J., R., Luthy, R., G. 1988; 54: 1182-1187
  • Microbial Ferrous Iron Oxidation in Acidic Solution Journal Water Pollution Control Federation Smith, J., R., Luthy, R., G., Middleton, A., W. 1988; 60 (4): 518-530
  • Complexation of Metals with Hydantoins Water Research Pavlovich, G., Z., Luthy, R., G. 1988; 23 (3): 327-336
  • Cementation of Cadmium on Zinc Water Science and Technology Luthy, R., G. 1987; 19: 1083-1088
  • Effect of Organic Solvent on Sorption of Aromatic Solutes onto Soils Journal of Environmental Engineering, ASCE Fu, J., K., Luthy, R., G. 1986; 112 (2): 346-366
  • Adsorption of Lead and Zinc on Blast Furnace Iron Oxide Solids Journal Water Pollution Control Federation Mihelcic, J., R., Luthy, R., G. 1986; 58 (3): 242-249
  • Blast Furnace Recycle Scrubber Water Quality and Reactions of Lead and Zinc Journal Water Pollution Control Federation Luthy, R., G., Sable, E., R., McMichael, F., C. 1986; 58 (3): 250-260
  • Aromatic Compound Solubility in Solvent/Water Mixtures Journal of Environmental Engineering, ASCE Fu, J., K., Luthy, R., G. 1986; 112 (2): 328-345
  • Prediction of Aromatic Solute Partition Coefficients Using the UNIFAC Group Contribution Model Environmental Science and Technology Campbell, J., R., Luthy, R., G. 1985; 19 (10): 980-985
  • Calcium Sulfate Solubility in Organic-Laden Wastewater Journal of Environmental Engineering, ASCE Banz, I., Luthy, R., G. 1985; 111 (3): 317-335
  • Discussion: Equilibrium Adsorption of Polycyclic Aromatic Hydrocarbons from Water onto Activated Carbon Environmental Science and Technology Walters, R., W., Luthy, R., G. 1985; 19 (9): 870-871
  • Equilibrium Adsorption of Polycyclic Aromatic Hydrocarbons from Water onto Activated Carbon Environmental Science and Technology Walters, R., W., Luthy, R., G. 1984; 18 (6): 395-403

    View details for Web of Science ID A1984ST45000006

    View details for PubMedID 22247939

  • Liquid-Suspended Solid Phase Partitioning of Polycyclic Aromatic Hydrocarbons in Coal Coking Wastewaters Water Research Walters, R., W., Luthy, R., G. 1984; 18 (7): 795-809
  • Biological Oxidation of Organic Constituents in Tar Sand Combustion Process Water Biotechnology and Bioengineering Torpy, M., F., Luthy, R., G. 1983; XXV: 3163-3176
  • Demineralization for Reuse of Coal Conversion Condensates Industrial and Engineering Chemistry: Process Design and Development Campbell, J., R., Luthy, R., G. 1983; 22 (3): 496-503
  • Removal of Organic Contaminants from Coal Conversion Condensates Journal Water Pollution Control Federation Luthy, R., G., Stamoudis, V., C., Campbell, J., R., Harrison, W. 1983; 55 (2): 196-207

    View details for Web of Science ID A1983RJ87200009

    View details for PubMedID 22288702

  • Measurement and Prediction of Distribution Coefficients for Aromatic Solutes Environmental Science and Technology Campbell, J., R., Luthy, R., G., Carrondo, M., J.T. 1983; 17 (10): 582-590
  • Chemical Equilibria in Split-Treatment Softening of Water Journal American Water Works Association Zipf, K., Luthy, R., G. 1981; 73 (6): 304-311
  • The Problem of Water Reuse in Coke Production Wastewater Reuse Luthy, R., G. edited by Middlebrooks, E., J. Ann Arbor Science Publishers, Inc.. 1981: 501-520
  • Treatment of Coal Coking and Coal Gasification Wastewaters Journal Water Pollution Control Federation Luthy, R., G. 1981; 53 (3): 325-339
  • Determination of Biological Removal of Organic Constituents in Quench Waters from High-BTU Coal Gasification Pilot Plants Water Research Stamoudis, V., C., Luthy, R., G. 1980; 14 (8): 1143-1156
  • The Production, Management and Chemistry of Coal Gasification Wastewaters Analytical Methods for Coal and Coal Products Luthy, R., G., Carter, M., J. edited by Baker, R., A. Academic Press. 1980: 137-167
  • Biological Treatment of a Coal Gasification Process Wastewater Water Research Luthy, R., G., T, J. 1980; 14 (9): 1269-1282
  • Biological Treatment of Synthetic Fuel Wastewater Journal of the Environmental Engineering Division ASCE Luthy, R., G., Sekel, D., J., Tallon, J., T. 1980; 106 (EE3): 609-629
  • Leach Characteristics of Coal Gasification Process Char Journal of the Environmental Engineering Division, ASCE Luthy, R., G., Vassiliou, P., Carter, M., J. 1980; 106 (EE1): 81-103
  • Biological Oxidation of Coke Plant Effluent Journal of the Environmental Engineering Division ASCE Luthy, R., G., Jones, L., D. 1980; 106 (EE4): 847-851
  • Cyanide and Thiocyanate in Coal Gasification Wastewaters Journal Water Pollution Control Federation Luthy, R., G., Bruce, S., G., Walters, R., W., Nakles, D., V. 1979; 51 (9): 2267-2282
  • Leaching Characteristics of Coal Gasification Process Ash and Char Proceedings of Symposium on Contaminants and Sediments, Chapter 9 Edwards, D., A., Laha, S., Liu, Z., Luthy, R., G. edited by Sabatini, D., A., Knox, R., C. Ann Arbor Science Publishers, Inc.. 1979: 159-168
  • Kinetics of Reaction of Cyanide and Reduced Sulfur Species in Aqueous Solution Environmental Science and Technology Luthy, R., G., Bruce Jr., S., G. 1979; 13 (12): 1481-1487
  • Removal of Emulsified Oil with Organic Coagulants and Dissolved Air Flotation Journal Water Pollution Control Federation Luthy, R., G., Selleck, R., E., Galloway, T., R. 1978; 50 (2): 331-346
  • Surface Properties of Petroleum Refinery Waste Oil Emulsions Environmental Science and Technology Luthy, R., G., Selleck, R., E., Galloway, T., R. 1977; 12 (11): 1211-1217
  • Underwater Construction Survey The Military Engineer Ciani, J., B., Brackett, R., L., Luthy, R., G. 1972; 62 (421): 315-318