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Mendez, M.; Lin, D.; Sutton, R. 2021. Study of Per- and Polyfluoroalkyl Substances in Bay Area POTWs: Phase 1, Sampling and Analysis Plan. SFEI Contribution No. 1020. San Francisco Estuary Institute: Richmond, CA.
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Miller, E.; Mendez, M.; Shimabuku, I.; Buzby, N.; Sutton, R. 2020. Contaminants of Emerging Concern in San Francisco Bay: A Strategy for Future Investigations 2020 Update. SFEI Contribution No. 1007. San Francisco Estuary Institute: Richmond, CA.

This 2020 CEC Strategy Update is a brief summary document that describes the addition of recently monitored CECs to the tiered risk-based framework. Reviews of findings relevant to San Francisco Bay are provided, as is a discussion of the role of environmental persistence in classifying CECs within the framework. The Strategy is a living document that guides RMP special studies on CECs, assuring continued focus on the issues of highest priority to protecting the health of the Bay. A key focus of the Strategy is a tiered risk-based framework that guides future monitoring proposals. The Strategy also features a multi-year plan indicating potential future research priorities.

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Heberger, M.; Sutton, R.; Buzby, N.; Sun, J.; Lin, D.; Mendez, M.; Hladik, M.; Orlando, J.; Sanders, C.; Furlong, E. 2020. Current-Use Pesticides, Fragrance Ingredients, and Other Emerging Contaminants in San Francisco Bay Margin Sediment and Water. SFEI Contribution No. 934. San Francisco Estuary Institute: Richmond, CA.

The Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) has recently focused attention on better characterization of contaminants in nearshore “margin” areas of San Francisco Bay. The margins of the Lower South Bay are mudflats and shallow regions that receive direct discharges of stormwater and wastewater; as a result, they may have higher levels of urban contaminants than the open Bay. In the summer of 2017, the RMP collected samples of margin
sediment in the South and Lower South Bay for analysis of legacy contaminants. The study described here leveraged that sampling effort by adding monitoring of sediment and water for two additional sets of emerging contaminants: 1) current-use pesticides; and 2) fragrance ingredients including the polycyclic musk galaxolide, as well as a range of other commonly detected emerging contaminants linked to toxicity concerns such as endocrine disruption.

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Journal Article (Peer-Reviewed)
Hung, C.; Klasios, N.; Zhu, X.; Sedlak, M.; Sutton, R. 2020. Methods Matter: Methods for Sampling Microplastic and Other Anthropogenic Particles and Their Implications for Monitoring and Ecological Risk Assessment. Integrated Environmental Assessment and Management 16 (6) . SFEI Contribution No. 1014.

To inform mitigation strategies and understand how microplastics affect wildlife, research is focused on understanding the sources, pathways, and occurrence of microplastics in the environment and in wildlife. Microplastics research entails counting and characterizing microplastics in nature, which is a labor‐intensive process, particularly given the range of particle sizes and morphologies present within this diverse class of contaminants. Thus, it is crucial to determine appropriate sampling methods that best capture the types and quantities of microplastics relevant to inform the questions and objectives at hand. It is also critical to follow protocols with strict quality assurance and quality control (QA/QC) measures so that results reflect accurate estimates of microplastic contamination. Here, we assess different sampling procedures and QA/QC strategies to inform best practices for future environmental monitoring and assessments of exposure. We compare microplastic abundance and characteristics in surface‐water samples collected using different methods (i.e., manta and bulk water) at the same sites, as well as duplicate samples for each method taken at the same site and approximate time. Samples were collected from 9 sampling sites within San Francisco Bay, California, USA, using 3 different sampling methods: 1) manta trawl (manta), 2) 1‐L grab (grab), and 3) 10‐L bulk water filtered in situ (pump). Bulk water sampling methods (both grab and pump) captured more microplastics within the smaller size range (<335 μm), most of which were fibers. Manta samples captured a greater diversity of morphologies but underestimated smaller‐sized particles. Inspection of pump samples revealed high numbers of particles from procedural contamination, stressing the need for robust QA/QC, including sampling and analyzing laboratory blanks, field blanks, and duplicates. Choosing the appropriate sampling method, combined with rigorous, standardized QA/QC practices, is essential for the future of microplastics research in marine and freshwater ecosystems.

Miller, E.; Klasios, N.; Lin, D.; Sedlak, M.; Sutton, R.; Rochman, C. 2020. Microparticles, Microplastics, and PAHs in Bivalves in San Francisco Bay. SFEI Contribution No. 976. San Francisco Estuary Institute: Richmond, CA.

California mussels (Mytilus californianus and hybrid Mytilus galloprovincialis / Mytilus trossulus) and Asian clams (Corbicula fluminea) were collected at multiple sites in San Francisco Bay. Mussels from a reference area with minimal urban influence were also deployed in cages for 90 days at multiple sites within the Bay prior to collection.Mussels from the reference time zero site, Bodega Head, had some of the lowest microparticle levels found in this study, along with resident clams from the San Joaquin and Sacramento Rivers and mussels transplanted to Pinole Point. The highest concentrations of microparticles were in mussels transplanted to Redwood Creek and Coyote Creek. The results of this study and current literature indicate that bivalves may not be good status and trends indicators of microplastic concentrations in the Bay unless the interest is in human health exposure via contaminated bivalve consumption.

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Journal Article (Peer-Reviewed)
Soberón, F. Sánchez; Sutton, R.; Sedlak, M.; Yee, D.; Schuhmacher, M.; Park, J. - S. 2020. Multi-box mass balance model of PFOA and PFOS in different regions of San Francisco Bay. Chemosphere 252 . SFEI Contribution No. 986.

We present a model to predict the long-term distribution and concentrations of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in estuaries comprising multiple intercommunicated sub-embayments. To that end, a mass balance model including rate constants and time-varying water inputs was designed to calculate levels of these compounds in water and sediment for every sub-embayment. Subsequently, outflows and tidal water exchanges were used to interconnect the different regions of the estuary. To calculate plausible risks to population, outputs of the model were used as inputs in a previously designed model to simulate concentrations of PFOA and PFOS in a sport fish species (Cymatogaster aggregata). The performance of the model was evaluated by applying it to the specific case of San Francisco Bay, (California, USA), using 2009 sediment and water sampled concentrations of PFOA and PFOS in North, Central and South regions. Concentrations of these compounds in the Bay displayed exponential decreasing trends, but with different shapes depending on region, compound, and compartment assessed. Nearly stable PFOA concentrations were reached after 50 years, while PFOS needed close to 500 years to stabilize in sediment and fish. Afterwards, concentrations stabilize between 4 and 23 pg/g in sediment, between 0.02 and 44 pg/L in water, and between 7 and 104 pg/g wet weight in fish, depending on compound and region. South Bay had the greatest final concentrations of pollutants, regardless of compartment. Fish consumption is safe for most scenarios, but due to model uncertainty, limitations in monthly intake could be established for North and South Bay catches.

Buzby, N.; Lin, D.; Sutton, R. 2020. Neonicotinoids and Their Degradates in San Francisco Bay Water. SFEI Contribution No. 1002. San Francisco Estuary Institute: Richmond, CA.

In the summer of 2017, open Bay water samples were collected during the RMP Status and Trends Water Cruise. Samples were analyzed for 19 neonicotinoids and metabolites. The only neonicotinoid detected was imidacloprid, an active ingredient used in both urban and agricultural applications. Imidacloprid was detected at a single site above the method detection limits (2.2-2.6 ng/L) in Lower South Bay at a level of 4.2 ng/L. This value is within the range of concentrations found in a separate RMP study in water samples collected from the South and Lower South Bay margins in 2017. Imidacloprid was detected at 3 of 12 of the margin sites at levels between 3.9 and 11 ng/L; no other neonicotinoids were detected. Of note, these RMP studies appear to represent the first evaluation of ambient neonicotinoid concentrations in an estuarine environment in the nation.

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Sun, J.; Sutton, R.; Ferguson, L.; Overdahl, K. 2020. New San Francisco Bay Contaminants Emerge. SFEI Contribution No. 931. San Francisco Estuary Institute: Richmond, CA.

In 2016, the RMP launched a novel investigation to detect new or unexpected contaminants in Bay waters, as well as treated sewage (or wastewater) discharged to the Bay. This study used non-targeted analysis, a powerful tool that provides a broad, open-ended view of thousands of synthetic and naturally-derived chemicals simultaneously. We identified hundreds of contaminants, and the results have opened our eyes to urban stormwater runoff as an important pathway for emerging contaminants to enter the Bay.

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Journal Article (Peer-Reviewed)
Miller, E.; Sedlak, M.; Lin, D.; Box, C.; Holleman, C.; Rochman, C. M.; Sutton, R. 2020. Recommended Best Practices for Collecting, Analyzing, and Reporting Microplastics in Environmental Media: Lessons Learned from Comprehensive Monitoring of San Francisco Bay. Journal of Hazardous Materials . SFEI Contribution No. 1023.

Microplastics are ubiquitous and persistent contaminants in the ocean and a pervasive and preventable threat to the health of marine ecosystems. Microplastics come in a wide variety of shapes, sizes, and plastic types, each with unique physical and chemical properties and toxicological impacts. Understanding the magnitude of the microplastic problem and determining the highest priorities for mitigation require accurate measures of microplastic occurrence in the environment and identification of likely sources. The field of microplastic pollution is in its infancy, and there are not yet widely accepted standards for sample collection, laboratory analyses, quality assurance/quality control (QA/QC), or reporting of microplastics in environmental samples. Based on a comprehensive assessment of microplastics in San Francisco Bay water, sediment, fish, bivalves, stormwater, and wastewater effluent, we developed recommended best practices for collecting, analyzing, and reporting microplastics in environmental media. We recommend factors to consider in microplastic study design, particularly in regard to site selection and sampling methods. We also highlight the need for standard QA/QC practices such as collection of field and laboratory blanks, use of methods beyond microscopy to identify particle composition, and standardized reporting practices, including suggested vocabulary for particle classification.

Davis, J.; Foley, M.; Askevold, R.; Buzby, N.; Chelsky, A.; Dusterhoff, S.; Gilbreath, A.; Lin, D.; Miller, E.; Senn, D.; et al. 2020. RMP Update 2020. SFEI Contribution No. 1008.

The overarching goal of the Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) is to answer the highest priority scientific questions faced by managers of Bay water quality. The RMP is an innovative collaboration between the San Francisco Bay Regional Water Quality Control Board, the regulated discharger community, the San Francisco Estuary Institute, and many other scientists and interested parties. The purpose of this document is to provide a concise overview of recent RMP activities and findings, and a look ahead to significant products anticipated in the next two years. The report includes a description of the management context that guides the Program; a brief summary of some of the most noteworthy findings of this multifaceted Program; and a summary of progress to date and future plans for addressing priority water quality topics.

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Journal Article (Peer-Reviewed)
Rochman, C. M.; Munno, K.; Box, C.; Cummins, A.; Zhu, X.; Sutton, R. 2020. Think Global, Act Local: Local Knowledge Is Critical to Inform Positive Change When It Comes to Microplastics. Environmental Science & Technology . SFEI Contribution No. 1024.

Microplastic contamination in the marine environment is a global issue. Across the world, policies at the national and international level are needed to facilitate the scale of change needed to tackle this significant problem. However, sources and patterns of plastic contamination vary around the world, and the most pressing actions differ from one location to another. Therefore, local policies are a critical part of the solution; recognizing local sources will enable mitigations with measurable impacts. Here, we highlight how investigating the contamination comprehensively in one location can inform relevant mitigation strategies that can be transferred globally. We examine the San Francisco Bay in California, USA—the largest estuary on the West Coast of the Americas, and home to over 7 million people. The local contamination of microplastics in surface water, sediments, and fish from this urban bay is reportedly higher than many places studied to date.(1) This example demonstrates the value of local monitoring in identifying sources, informing local mitigation strategies and developing an array of solutions to stem the multifaceted tide of plastic pollution entering our global oceans.

Sutton, R.; Chen, D.; Sun, J.; Greig, D. J.; Wu, Y. 2019. Characterization of brominated, chlorinated, and phosphate flame retardants in San Francisco Bay, an urban estuary. Science of the Total Environment 652, 212-223 . SFEI Contribution No. 859.

Flame retardant chemical additives are incorporated into consumer goods to meet flammability standards, and many have been detected in environmental matrices. A uniquely wide-ranging characterization of flame retardants was conducted, including polybrominated diphenyl ethers (PBDEs) and 52 additional brominated, chlorinated, or phosphate analytes, in water, sediment, bivalves, and harbor seal blubber of San Francisco Bay, a highly urbanized estuary once considered a hot spot for PBDE contamination. Among brominated flame retardants, PBDEs remained the dominant contaminants in all matrices, though declines have been observed over the last decade following their phase-out. Hexabromocyclododecane (HBCD) and other hydrophobic, brominated flame retardants were commonly detected at lower levels than PBDEs in sediment and tissue matrices. Dechlorane Plus (DP) and related chlorinated compounds were also detected at lower levels or not at all across all matrices. In contrast, phosphate flame retardants were widely detected in Bay water samples, with highest median concentrations in the order TCPP > TPhP > TBEP > TDCPP > TCEP. Concentrations in Bay water were often higher than in other estuarine and marine environments. Phosphate flame retardants were also widely detected in sediment, in the order TEHP > TCrP > TPhP > TDCPP > TBEP. Several were present in bivalves, with levels of TDCPP comparable to PBDEs. Only four phosphate flame retardants were detected in harbor seal blubber: TCPP, TDCPP, TCEP, and TPhP. Periodic, multi-matrix screening is recommended to track contaminant trends impacted by changes to flammability standards and manufacturing practices, with a particular focus on contaminants like TDCPP and TPhP that were found at levels comparable to thresholds for aquatic toxicity.

Sedlak, M.; Sutton, R.; Miller, L.; Lin, D. 2019. Microplastic Strategy Update. SFEI Contribution No. 951. San Francisco Estuary Institute: Richmond, CA.

Based on the detection of microplastics in San Francisco Bay surface water and Bay Area wastewater effluent in 2015, the Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) convened a Microplastic Workgroup (MPWG) in 2016 to discuss the issue, identify management information needs and management questions (MQs), and prioritize studies to provide information to answer these management questions. The MPWG meets annually to review on-going microplastic projects and to conduct strategic long-term planning in response to new information in this rapidly evolving field.

In this nascent field with new findings published almost daily, the Strategy is designed to be a living document that is updated periodically. This Strategy Update includes a short summary of recent findings from the San Francisco Bay Microplastics Project - a major monitoring effort in the Bay - and an updated multi-year plan based on the newly acquired knowledge and current management needs.

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Book Chapter
Sutton, R.; Xie, Y.; Moran, K. D.; Teerlink, J. 2019. Occurrence and Sources of Pesticides to Urban Wastewater and the Environment. In Pesticides in Surface Water: Monitoring, Modeling, Risk Assessment, and Management. Pesticides in Surface Water: Monitoring, Modeling, Risk Assessment, and Management. American Chemical Society: Washington, DC. pp 63-88.

Municipal wastewater has not been extensively examined as a pathway by which pesticides contaminate surface water, particularly relative to the well-recognized pathways of agricultural and urban runoff. A state-of-the-science review of the occurrence and fate of current-use pesticides in wastewater, both before and after treatment, indicates this pathway is significant and should not be overlooked. A comprehensive conceptual model is presented to establish all relevant pesticide-use patterns with the potential for both direct and indirect down-the-drain transport. Review of available studies from the United States indicates 42 pesticides in current use. While pesticides and pesticide degradates have been identified in wastewater, many more have never been examined in this matrix. Conventional wastewater treatment technologies are generally ineffective at removing pesticides from wastewater, with high removal efficiency only observed in the case of highly hydrophobic compounds, such as pyrethroids. Aquatic life reference values can be exceeded in undiluted effluents. For example, seven compounds, including three pyrethroids, carbaryl, fipronil and its sulfone degradate, and imidacloprid, were detected in treated wastewater effluent at levels exceeding U.S. Environmental Protection Agency (US EPA) aquatic life benchmarks for chronic exposure to invertebrates. Pesticides passing through wastewater treatment plants (WWTPs) merit prioritization for additional study to identify sources and appropriate pollution-prevention strategies. Two case studies, diazinon and chlorpyrifos in household pesticide products, and fipronil and imidacloprid in pet flea control products, highlight the importance of identifying neglected sources of environmental contamination via the wastewater pathway. Additional monitoring and modeling studies are needed to inform source control and prevention of undesirable alternative solutions.

Sutton, R.; Lin, D.; Sedlak, M.; Box, C.; Gilbreath, A.; Holleman, R.; Miller, L.; Wong, A.; Munno, K.; Zhu, X.; et al. 2019. Understanding Microplastic Levels, Pathways, and Transport in the San Francisco Bay Region. SFEI Contribution No. 950. San Francisco Estuary Institute: Richmond, CA.

Microplastics (particles less than 5 mm) are ubiquitous and persistent pollutants in the ocean and a pervasive and preventable threat to the health of marine ecosystems. Microplastics come in a wide variety of shapes, sizes, and plastic types, each with unique physical and chemical properties and toxicological impacts. Understanding the magnitude of the microplastics problem and determining the highest priorities for mitigation require accurate measures of microplastic occurrence in the environment and identification of likely sources.

To develop critical baseline data and inform solutions, the San Francisco Estuary Institute and the 5 Gyres Institute have completed the first comprehensive regional study of microplastic pollution in a major estuary. This project supported multiple scientific components to develop improved knowledge about and characterization of microparticles and microplastics in San Francisco Bay and adjacent National Marine Sanctuaries, with the following objectives:

  1. Contribute to the development and standardization of sample collection and analysis methodology for microplastic transportation research.
  2. Determine a baseline for future monitoring of microplastics in San Francisco Bay surface water, sediment, and fish, and in ocean waters outside the Golden Gate.
  3. Characterize pathways by which microplastics enter the Bay, including urban stormwater and treated wastewater effluent.
  4. Investigate the contribution of Bay microplastics to the adjacent National Marine Sanctuaries through computer simulations.
  5. Communicate findings to regional stakeholders and the general public through meetings and educational materials.
  6. Facilitate evaluation of policy options for San Francisco Bay, with recommendations on source reduction.

This document presents the findings of this three-year project. A companion document, “San Francisco Bay Microplastics Project: Science-Supported Solutions and Policy Recommendations,” has been developed by 5 Gyres using the findings of this study (Box and Cummins, 2019).

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Lin, D.; Sutton, R. 2018. Alternative Flame Retardants in San Francisco Bay: Synthesis and Strategy. SFEI Contribution No. 885. San Francisco Estuary Institute : Richmond, CA.
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Sedlak, M.; Sutton, R.; Wong, A.; Lin, D. 2018. Per and Polyfluoroalkyl Substances (PFAS) in San Francisco Bay: Synthesis and Strategy. SFEI Contribution No. 867. San Francisco Estuary Institute : Richmond, CA.
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Lin, D.; Sutton, R.; Sun, J.; Ross, J. 2018. Screening of Pharmaceuticals in San Francisco Bay Wastewater. SFEI Contribution No. 910. San Francisco Estuary Institute : Richmond, CA.
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Journal Article (Peer-Reviewed)
Wu, Y.; Tan, H.; Sutton, R.; Chen, D. 2017. From Sediment to Top Predators: Broad Exposure of Polyhalogenated Carbazoles in San Francisco Bay (U.S.A.). Environmental Science and Technology 51, 2038-2046.

The present study provides the first comprehensive investigation of polyhalogenated carbazoles (PHCZ) contamination in an aquatic ecosystem. PHCZs have been found in soil and aquatic sediment from several different regions, but knowledge of their bioaccumulation and trophodynamics is extremely scarce. This work investigated a suite of 11 PHCZ congeners in San Francisco Bay (United States) sediment and organisms, including bivalves (n = 6 composites), sport fish (n = 12 composites), harbor seal blubber (n = 18), and bird eggs (n = 8 composites). The most detectable congeners included 3,6-dichlorocarbazole (36-CCZ), 3,6-dibromocarbazole (36-BCZ), 1,3,6-tribromocarbazole (136-BCZ), 1,3,6,8-tetrabromocarbazole (1368-BCZ), and 1,8-dibromo-3,6-dichlorocarbazole (18-B-36-CCZ). The median concentrations of ΣPHCZs were 9.3 ng/g dry weight in sediment and ranged from 33.7 to 164 ng/g lipid weight in various species. Biomagnification was observed from fish to harbor seal and was mainly driven by chlorinated carbazoles, particularly 36-CCZ. Congener compositions of PHCZs differed among species, suggesting that individual congeners may be subject to different bioaccumulation or metabolism in species occupying various trophic levels in the studied aquatic system. Toxic equivalent (TEQ) values of PHCZs were determined based on their relative effect potencies (REP) compared to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The median TEQ was 1.2 pg TEQ/g dry weight in sediment and 4.8 – 19.5 pg TEQ/g lipid weight in biological tissues. Our study demonstrated the broad exposure of PHCZs in San Francisco Bay and their characteristics of bioaccumulation and biomagnification along with dioxin-like effects. These findings raise the need for additional research to better elucidate their sources, environmental behavior, and fate in global environments.

Sutton, R.; Sedlak, M. 2017. Microplastic Monitoring and Science Strategy for San Francisco Bay. SFEI Contribution No. 798. San Francisco Estuary Institute: Richmond, Calif.
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Journal Article (Peer-Reviewed)
Sadaria, A. M.; Sutton, R.; Moran, K. D.; Teerlink, J.; Brown, J. V.; Halden, R. U. 2017. Passage of fiproles and imidacloprid from urban pest control uses through wastewater treatment plants in northern California. Environmental Toxicology and Chemistry 36, 1473-1482 . SFEI Contribution No. 783.

Urban pest control insecticides, specifically fipronil and its four major degradates (fipronil sulfone, sulfide, desulfinyl, and amide) and imidacloprid, were monitored during drought conditions in eight San Francisco Bay wastewater treatment plants (WWTPs). In influent and effluent, ubiquitous detections were obtained in units of ng/L for fipronil (13-88), fipronil sulfone (1-28), fipronil sulfide (1-5) and imidacloprid (58-306). In influent, 100% of imidacloprid and 62 ± 9% of total fiproles (fipronil and degradates) were present in the dissolved state, with the balance being bound to filter-removable particulates. Targeted insecticides persisted during wastewater treatment, regardless of treatment technology utilized (imidacloprid: 93 ± 17%; total fiproles: 65 ± 11%), with partitioning into sludge (3.7-151.1 μg/kg dry weight as fipronil) accounting for minor losses of total fiproles entering WWTPs. The load of total fiproles was fairly consistent across the facilities but fiprole speciation varied. This first regional study on fiprole and imidacloprid occurrences in raw and treated California sewage revealed ubiquity and marked persistence to conventional treatment of both phenylpyrazole and neonicotinoid compounds. Flea and tick control agents for pets are identified as potential sources of pesticides in sewage meriting further investigation and inclusion in chemical-specific risk assessments. 

Sutton, R. 2016. Microplastic Contamination in San Francisco Bay - Fact Sheet. 2015, Revised 2016. SFEI Contribution No. 770.
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Journal Article (Peer-Reviewed)
Sutton, R.; Mason, S. A.; Stanek, S. K.; Willis-Norton, E.; Wren, I. F.; Box, C. 2016. Microplastic contamination in the San Francisco Bay, California, USA. Marine Pollution Bulletin 109 . SFEI Contribution No. 769.

Despite widespread detection of microplastic pollution in marine environments, data describing microplastic abundance in urban estuaries and microplastic discharge via treated municipal wastewater are limited. This study presents information on abundance, distribution, and composition of microplastic at nine sites in San Francisco Bay, California, USA. Also presented are characterizations of microplastic in final effluent from eight wastewater treatment plants, employing varying treatment technologies, that discharge to the Bay. With an average microplastic abundance of 700,000 particles/km2, Bay surface water appears to have higher microplastic levels than other urban waterbodies sampled in North America. Moreover, treated wastewater from facilities that discharge into the Bay contains considerable microplastic contamination. Facilities employing tertiary filtration did not show lower levels of contamination than those using secondary treatment. As textile-derived fibers were more abundant in wastewater, higher levels of fragments in surface water suggest additional pathways of microplastic pollution, such as stormwater runoff.

Houtz, E. F.; Sutton, R.; Park, J. - S.; Sedlak, M. 2016. Poly- and perfluoroalkyl substances in wastewater: Significance of unknown precursors, manufacturing shifts, and likely AFFF impacts. Water Research . SFEI Contribution No. 780.

In late 2014, wastewater effluent samples were collected from eight treatment plants that discharge to San Francisco (SF) Bay in order to assess poly- and perfluoroalkyl substances (PFASs) currently released from municipal and industrial sources. In addition to direct measurement of twenty specific PFAS analytes, the total concentration of perfluoroalkyl acid (PFAA) precursors was also indirectly measured by adapting a previously developed oxidation assay. Effluent from six municipal treatment plants contained similar amounts of total PFASs, with highest median concentrations of PFHxA (24 ng/L), followed by PFOA (23 ng/L), PFBA (19 ng/L), and PFOS (15 ng/L). Compared to SF Bay municipal wastewater samples collected in 2009, the short chain perfluorinated carboxylates PFBA and PFHxA rose significantly in concentration. Effluent samples from two treatment plants contained much higher levels of PFASs: over two samplings, wastewater from one municipal plant contained an average of 420 ng/L PFOS and wastewater from an airport industrial treatment plant contained 560 ng/L PFOS, 390 ng/L 6:2 FtS, 570 ng/L PFPeA, and 500 ng/L PFHxA. The elevated levels observed in effluent samples from these two plants are likely related to aqueous film forming foam (AFFF) sources impacting their influent; PFASs attributable to both current use and discontinued AFFF formulations were observed. Indirectly measured PFAA precursor compounds accounted for 33%–63% of the total molar concentration of PFASs across all effluent samples and the PFAA precursors indicated by the oxidation assay were predominately short-chained. PFAS levels in SF Bay effluent samples reflect the manufacturing shifts towards shorter chained PFASs while also demonstrating significant impacts from localized usage of AFFF.

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Sutton, R.; Kucklick, J. 2015. A Broad Scan of Bay Contaminants. San Francisco Estuary Institute: Richmond, CA.
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Sutton, R.; Sedlak, M. 2015. Contaminants of Emerging Concern in San Francisco Bay: A Strategy for Future Investigations. 2015 Update. Contaminants of Emerging Concern in San Francisco Bay: A Strategy for Future Investigations. SFEI Contribution No. 761. San Francisco Estuary Institute: Richmond, CA.

About this Update

The Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) has been investigating contaminants of emerging concern (CECs) since 2001. CECs can be broadly defined as synthetic or naturally occurring chemicals that are not regulated or commonly monitored in the environment but have the potential to enter the environment and cause adverse ecological or human health impacts.

The RMP Emerging Contaminants Workgroup (ECWG), established in 2006, includes representatives from RMP stakeholder groups, regional scientists, and an advisory panel of expert researchers that work together to address the workgroup’s guiding management question – Which CECs have the potential to adversely impact beneficial uses in San Francisco Bay? The overarching goal of the ECWG is to develop cost-effective strategies to identify and monitor CECs to minimize impacts to the Bay.

To this end, the RMP published a CEC Strategy document in 2013 (Sutton et al. 2013). The strategy is a living document that guides RMP special studies on CECs, assuring continued focus on the issues of highest priority to the health of the Bay. A key focus of the strategy is a tiered risk and management action framework that guides future monitoring proposals. The strategy also features a multi-year plan indicating potential future research priorities.

This 2015 CEC strategy update features revised designations of CECs in the tiered risk and management action framework based on monitoring and research conducted since 2013. Brief summaries of relevant RMP findings are provided. In addition, a proposed multi-year plan for future RMP Special Studies on CECs is outlined. A full revision of the CEC strategy is anticipated in 2016. 

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Journal Article (Peer-Reviewed)
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