2018-2019 Executive Summary
The quality of sediment that underlies water bodies is a sentinel indicator of the health of marine ecosystems. Pollutants discharged from wastewater treatment plants and urban watersheds have led to sediment contamination along California’s coastline, with contamination levels most acute in bays and estuaries, where slower-flowing waters promote settling of contaminant-laden particles. SCCWRP has been at the forefront of efforts to quantify, monitor and develop solutions to remediate contaminated sediment. SCCWRP and its collaborators have advanced sediment-quality science into the regulatory arena through the development of a widely applicable sediment quality assessment framework designed to gauge the impacts of sediment contamination on bottom-dwelling organisms. In California, this assessment framework has become the technical foundation for implementing the state’s Sediment Quality Objectives program that went into effect in 2009. SCCWRP also is developing an additional assessment framework that applies sophisticated mathematical models to quantify how contamination from sediment moves through the food web and bioaccumulates in wildlife and humans.
SCCWRP’s research falls into two main categories that reflect the two main routes by which organisms become exposed to sediment contamination: direct exposure, where bottom-dwelling marine life come into contact with and/or ingests contamination in sediment, and indirect exposure, where predators accumulate pollutants in their bodies as they consume contaminated prey. Each exposure route calls for a different conceptual approach to build a comprehensive assessment framework that can accurately measure and estimate the impacts of sediment contamination on the organisms exposed to it, including humans. SCCWRP’s goal is to build a common, agreed-upon technical foundation for assessing sediment quality to help water-quality managers make better-informed decisions about sediment remediation and clean-up activities.
This year, SCCWRP is continuing its work across both the direct and indirect exposure arenas, as well as pursuing case studies that can assist in translating sediment science to application by environmental managers. SCCWRP’s focus for 2018-19 will be on:
- Direct effects on sediment quality: To build upon research focusing on the impacts of direct exposure to contaminated sediment, SCCWRP is pursuing projects across all three lines of evidence used in sediment quality assessments. In the chemistry arena, SCCWRP is studying how to accurately measure the freely dissolved concentration of sediment contamination by a technique known as passive sampling. In the biological assessment arena, SCCWRP is evaluating how to use DNA barcoding to rapidly assess the condition of marine benthic invertebrate communities, and is also adapting benthic indices for use in low-salinity environments. Research is also underway to develop a rapid causal assessment framework for macrofaunal community impacts in embayments. In the toxicology arena, SCCWRP is investigating the impact of ocean acidification on contaminant bioavailability and sediment toxicity.
- Indirect effects on sediment quality: To assess sediment contamination’s health risks for humans and wildlife, SCCWRP is continuing to refine bioaccumulation models and assessment frameworks that integrate chemical exposure and sediment contaminant linkage indicators. In the sediment linkage arena, SCCWRP is using passive sampling and tissue contamination measurements to improve the ability of bioaccumulation models to address the influence of dissolved contamination in the water column on food web contaminant transfer.
- Sediment quality objectives implementation: To support implementation of new evaluation tools for assessing sediment quality impacts on human health, SCCWRP is continuing to update its technical support resources and guidance documents.