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Filters: Author is Alicia N Gilbreath  [Clear All Filters]
2019
Yee, D.; Gilbreath, A. N.; McKee, L. J. .; Davis, J. A. 2019. Conceptual Model to Support PCB Management and Monitoring in the San Leandro Bay Priority Margin Unit - Final Report. SFEI Contribution No. 928. San Francisco Estuary Institute: Richmond, CA.

The goal of RMP PCB special studies over the next few years is to inform the review and possible revision of the PCB TMDL and the reissuance of the Municipal Regional Permit for Stormwater, both of which are tentatively scheduled to occur in 2020. Conceptual model development for a set of four representative priority margin units will provide a foundation for establishing an effective and efficient monitoring plan to track responses to load reductions, and will also help guide planning of management actions. The Emeryville Crescent was the first PMU to be studied in 2015-2016. The San Leandro Bay PMU is second (2016-2018), Steinberger Slough in San Carlos is third (2018), and Richmond Harbor will be fourth (2018-2019).

This document is Phase Three of a report on the conceptual model for San Leandro Bay. A Phase One report (Yee et al. 2017) presented analyses of watershed loading, initial retention, and long-term fate, including results of sediment sampling in 2016. A Phase Two data report (Davis et al. 2017) documented the methods, quality assurance, and all of the results of the 2016 field study. This Phase Three report is the final report that incorporates all of the results of the 2016 field study, and includes additional discussion of the potential influence of contaminated sites in the
watershed, the results of passive sampling by Stanford researchers and a comparative analysis of long-term fate in San Leandro Bay and the Emeryville Crescent, a section on bioaccumulation, and a concluding section with answers to the management questions that were the impetus for the work.

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Gilbreath, A.; McKee, L.; Shimabuku, I.; Lin, D.; Werbowski, L. M.; Zhu, X.; Grbic, J.; Rochman, C. 2019. Multi-year water quality performance and mass accumulation of PCBs, mercury, methylmercury, copper and microplastics in a bioretention rain garden. Journal of Sustainable Water in the Built Environment 5 (4) . SFEI Contribution No. 872.

A multiyear water quality performance study of a bioretention rain garden located along a major urban transit corridor east of San Francisco Bay was conducted to assess the efficacy of bioretention rain gardens to remove pollutants. Based on data collected in three years between 2012 and 2017, polychlorinated biphenyls (PCBs) and suspended sediment concentrations (SSCs) were reduced (>90%), whereas total mercury (Hg), methylmercury (MeHg), and copper (Cu) were moderately captured (37%, 49%, and 68% concentration reduction, respectively). Anthropogenic microparticles including microplastics were retained by the bioretention rain garden, decreasing in concentration from 1.6 particles/L to 0.16 particles/L. Based on subsampling at 50- and 150-mm intervals in soil cores from two areas of the unit, PCBs, Hg, and MeHg were all present at the highest concentrations in the upper 100 mm in the surface media layers. Based on residential screening concentrations, the surface media layer near the inlet would need to be removed and replaced annually, whereas the rest of the unit would need replacement every 8 years. The results of this study support the use of bioretention in the San Francisco Bay Area as one management option for meeting load reductions required by San Francisco Bay total maximum daily loads, and provide useful data for supporting decisions about media replacement and overall maintenance schedules.

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Gilbreath, A.; Hunt, J.; Mckee, L. 2019. Pollutants of Concern Reconnaissance Monitoring Progress Report, Water Years 2015-2018. SFEI Contribution No. 942. San Francisco Estuary Institute: Richmond, CA.
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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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2018
Gilbreath, A.; Pearce, S.; Shimabuku, I.; McKee, L. 2018. Bay Area Green Infrastructure Water Quality Synthesis. SFEI Contribution No. 922. San Francisco Estuary Institute : Richmond, CA.
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Gilbreath, A.; Wu, J.; Hunt, J.; McKee, L. 2018. Pollutants of Concern Reconnaissance Monitoring Water Years 2015, 2016, and 2017. SFEI Contribution No. 840. San Francisco Estuary Institute: Richmond, CA.
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Wu, J.; Trowbridge, P.; Yee, D.; McKee, L.; Gilbreath, A. 2018. RMP Small Tributaries Loading Strategy: Modeling and Trends Strategy 2018. SFEI Contribution No. 886. San Francisco Estuary Institute : Richmond, CA.
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2015
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Gilbreath, A. N.; McKee, L. J. . 2015. Concentrations and loads of PCBs, dioxins, PAHs, PBDEs, OC pesticides and pyrethroids during storm and low flow conditions in a small urban semi-arid watershed. Science of the Total Environment 526, 251-261 . SFEI Contribution No. 650.

Urban runoff has been identified in water quality policy documents for San Francisco Bay as a large and potentially controllable source of pollutants. In response, concentrations of suspended sediments and a range of trace organic pollutants were intensively measured in dry weather and storm flow runoff from a 100% urban watershed. Flow in this highly urban watershed responded very quickly to rainfall and varied widely resulting in rapid changes of turbidity, suspended sediments and pollutant concentrations. Concentrations of each organic pollutant class were within similar ranges reported in other studies of urban runoff, however comparison was limited for several of the pollutants given information scarcity. Consistently among PCBs, PBDEs, and PAHs, the more hydrophobic congeners were transported in larger proportions during storm flows relative to low flows. Loads for Water Years 2007-2010 were estimated using regression with turbidity during the monitored months and a flow weighted mean concentration for unmonitored dry season months. More than 91% of the loads for every pollutant measured were transported during storm events, along with 87% of the total discharge. While this dataset fills an important local data gap for highly urban watersheds of San Francisco Bay, the methods, the uniqueness of the analyte list, and the resulting interpretations have applicability for managing pollutant loads in urban watersheds in other parts of the world.

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2014
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