Microparticles, Microplastics, and PAHs in Bivalves in San Francisco Bay

San Francisco Estuary Institute (SFEI) | November 15th, 2019

Microplastic contamination in the San Francisco Bay, California, USA

Marine Pollution Bulletin (Elsevier) | August 15th, 2015

Despite widespread detection of microplastic pollution in marine environments, data describing microplastic abundance in urban estuaries and microplastic discharge via tr

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 stormwaterrunoff.

Microplastic pollution in the water column and benthic sediment of the San Pedro Bay, California, USA

Environmental Research (Elsevier) | January 21st, 2025

The concentration, character, and distribution of microplastics in coastal marine environments remain poorly understood, with most research focusing on the abundance of m

The concentration, character, and distribution of microplastics in coastal marine environments remain poorly understood, with most research focusing on the abundance of microplastics at the sea surface. To address this gap, we conducted one of the first comprehensive assessments of microplastic distribution through the marine water column and benthic sediment during the wet and dry season in the coastal waters of the San Pedro Bay Southern California, USA. Microplastic concentrations in the water column did not vary significantly across season but were significantly higher in nearshore environments and at the surface of the water column. Sediment samples contained significantly more microplastics in the wet season and in offshore environments. Black particles were the most dominant color, while fibers were the most abundant morphology, accounting for over 50% of both water column and sediment microplastics. Polyethylene and polypropylene were identified as the most abundant polymers in the water column regardless of morphology type. Tire and road wear particles were found through the study domain. Average microplastic concentrations in the San Pedro Bay were estimated to be 8.65 × 105 ± 7.60 × 105 particles/km2 and 3.19 ± 2.96 particles/m³. This study highlights the complexity of microplastic concentration, character, and distribution in marine environments and demonstrates that surface only sampling strategies significantly underestimate microplastic concentrations. Our findings underscore the need for continued and expanded research into microplastic distribution and transport dynamics across the marine environment to aid in understanding, managing, and mitigating plastic pollution in coastal marine systems.

Microplastic pollution is widely detected in US municipal wastewater treatment plant effluent

Environmental Pollution (Elsevier) | August 27th, 2016

Municipal wastewater effluent has been proposed as one pathway for microplastics to enter the aquatic environment. Here we present a broad study of municipal wastewater t

Municipal wastewater effluent has been proposed as one pathway for microplastics to enter the aquatic environment. Here we present a broad study of municipal wastewater treatment plant effluent as a pathway for microplastic pollution to enter receiving waters. A total of 90 samples were analyzed from 17 different facilities across the United States. Averaging all facilities and sampling dates, 0.05 ± 0.024 microparticles were found per liter of effluent. Though a small value on a per liter basis, even minor municipal wastewater treatment facilities process millions of liters of wastewater each day, yielding daily discharges that ranged from ∼50,000 up to nearly 15 million particles. Averaging across the 17 facilities tested, our results indicate that wastewater treatment facilities are releasing over 4 million microparticles per facility per day. Fibers and fragments were found to be the most common type of particle within the effluent; however, some fibers may be derived from non-plastic sources. Considerable inter- and intra-facility variation in discharge concentrations, as well as the relative proportions of particle types, was observed. Statistical analysis suggested facilities serving larger populations discharged more particles. Results did not suggest tertiary filtration treatments were an effective means of reducing discharge. Assuming that fragments and pellets found in the effluent arise from the ‘microbeads’ found in many cosmetics and personal care products, it is estimated that between 3 and 23 billion (with an average of 13 billion) of these microplastic particles are being released into US waterways every day via municipal wastewater. This estimate can be used to evaluate the contribution of microbeads to microplastic pollution relative to other sources (e.g., plastic litter and debris) and pathways (e.g., stormwater) of discharge.

Microplastic Strategy Update on behalf of the Regional Monitoring Program (RMP) for Water Quality in San Francisco Bay

San Francisco Estuary Institute (SFEI) | December 2nd, 2019

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

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.

Missing the Boat on Freshwater Fish Conservation in California

Conservation Letters (Society for Conservation Biology) | March 30th, 2016

Population growth and increasing water‐use pressures threaten California's freshwater ecosystems and have led many native fishes to the brink of extinction. To guide fi

Population growth and increasing water‐use pressures threaten California's freshwater ecosystems and have led many native fishes to the brink of extinction. To guide fish conservation efforts, we provide the first systematic prioritization of river catchments and identify those that disproportionately contribute to fish taxonomic diversity. Using high‐resolution range maps of exceptional quality, we also assess the representation of fish taxa within the state's protected areas and examine the concordance of high‐priority catchments with existing reserves and among distinct taxonomic groups. Although most of the state's native fishes are found within protected areas, only a small proportion of their ranges are represented. Few high‐priority catchments occur within protected areas, suggesting that fish conservation will require active management and targeted river restoration outside of reserves. These results provide the foundation for systematic freshwater conservation planning in California and for prioritizing where limited resources are allocated for fish recovery and protection.

Mission Bay Historical Ecology Reconnaissance Study: Data Collection Summary (Technical Report)

San Francisco Estuary Institute (SFEI) | February 1st, 2016

The goals of the Mission Bay Historical Ecology Reconnaissance Study were to collect and compile high-priority historical data about the Mission Bay landscape, identify

The goals of the Mission Bay Historical Ecology Reconnaissance Study were to collect and compile high-priority historical data about the Mission Bay landscape, identify sources that could help to develop a deeper understanding of early ecological conditions, and to identify future possible research directions based on the available data. This technical memorandum is intended to document the archives consulted during the reconnaissance study, summarize the collected and compiled data, and to identify potential next steps. A separate technical presentation to project staff and advisors will summarize the preliminary findings and questions generated from a review of the historical dataset. Ultimately, this research is intended to support the San Diego Audubon Society’s Mission Bay Wetlands Conceptual Restoration Plan (CRP) and the ReWild Mission Bay project. Also on this topic: Mission Bay Historical Ecology Reconnaissance Study: Data CollectionSummary and Initial Findings (Presentation)

Modeling Functional Flows in California’s Rivers

Frontiers in Environmental Science (Frontiers) | March 11th, 2022

Modeling guides groundwater management in a basin with river–aquifer interactions

California Agriculture (UCANR) | March 13th, 2018

The Sustainable Groundwater Management Act (SGMA) of 2014 seeks to maintain groundwater discharge to streams to support environmental goals. In Scott Valley, in Siskiyou

The Sustainable Groundwater Management Act (SGMA) of 2014 seeks to maintain groundwater discharge to streams to support environmental goals. In Scott Valley, in Siskiyou County, the Scott River and its tributaries are an important salmonid spawning habitat, and about 10% of average annual Scott River stream flow comes from groundwater. The local groundwater advisory committee is developing groundwater management alternatives that would increase summer and early fall stream flows. We developed a model to provide a framework to evaluate those alternatives. We first created a water budget for the Scott Valley groundwater basin and integrated the detailed, spatiotemporally distributed water budget results into a computer model of the basin that simultaneously accounted for groundwater flow, stream flow and landscape water fluxes. Different conceptual representations (using the MODFLOW RIV package and MODFLOW SFR package) of the stream–aquifer boundary provided significantly different results in the seasonal dynamics of groundwater–surface water fluxes. As groundwater sustainability agencies draw up plans to meet SGMA requirements, they must choose and test simulation tools carefully.

Modeling residential development in California from 2000 to 2050: Integrating wildfire risk, wildland and agricultural encroachment

Land Use Policy (Elsevier) | November 1st, 2014

Between 1940 and 2000, nearly 10 million housing units were constructed throughout California. This increased interaction between human and natural communities creates a

Between 1940 and 2000, nearly 10 million housing units were constructed throughout California. This increased interaction between human and natural communities creates a number of significant socio-ecological challenges. Here we present a novel spatially explicit model that allows better characterization of the extent and intensity of future housing settlements using three development scenarios between 2000 and 2050. We estimate that California’s exurban land classes will replace nearly 12 million acres of wild and agricultural lands. This will increase threats to ecosystems and those presented by wild fire, as the number of houses in ‘very high’ wildfire severity zones increases by nearly 1 million.