Comparison of sediment quality assessment methods for the ocean monitoring of the San Pedro Shelf

Data collected by the Orange County Sanitation District Ocean Monitoring Program was used to assess the long-term trends and spatial extent of chemical contamination and toxicity in the sediments off the San Pedro Shelf. The objective of this paper is to determine the relative degree of toxicity in the environment, the spatial distribution of toxicity, if any, and the changes in toxicity along a gradient of pollution or with respect to distance from pollutant sources. Methods in analyzing these objectives include comparing two approaches in Sediment Quality Assessments: interstitial (porewater) water toxicity and whole sediment toxicity. Results indicate disagreement between testing techniques, which showed varying levels of low to high toxicity. The whole sediment toxicity test results report low levels of toxicity at sampling stations over time, while porewater toxicity results show moderate to high toxicity at sampling stations over time.