Title

A Review of the Doc Model for Development of Site-Specific Criteria for Maintenance of Protective Copper Concentrations in San Francisco Bay, California, Usa

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological and Environmental Sciences

Date of Award

Summer 2015

Abstract

The development of protective criteria for copper concentrations in a body of water has been a dynamic process, because copper has been shown to elicit a biphasic dose response. Aquatic organisms are particularly vulnerable to experiencing potential deleterious effects in response to increased concentrations of copper. Copper is highly reactive and readily binds to the substrate or enters into a variety of coordination complexes with various ligands, which include the biological ligands found within the tissue of aquatic organisms, thus causing many potential ill effects. The United States Environmental Protection Agency has determined that a need exists for the establishment of site-specific criteria to protect organisms from these ill effects. Historically, the Water Effect Ratio process (WER) was used for this purpose. More recently, the characterization of local water chemistry has been enhanced through a biotic ligand model (BLM). However, a BLM has not yet been parameterized for saltwater systems. If comparable to the WER method, the dissolved organic carbon (DOC) method developed by Arnold (2005) could act as a surrogate to the BLM because the lower cost and decreased demand for technical expertise allows for greater temporal and spatial characterization of saltwater systems (similar to BLM). Copper and DOC data were retrieved from the San Francisco Estuary Institute database for 2002-2013 and used to make copper criteria predictions based on DOC. These predictions were then compared to the WER-based national and regional standards for copper criteria for the San Francisco Bay system to determine comparability of the two methods. Results demonstrated that the DOC generally predicted more conservative (i.e., more strict) criteria for the bay area. According to the results of five sampling sites studied, criteria levels for one site (BA30) should be more protective, while they could be less protective in the other four. However, while data for all sites were found to be in compliance with the established criteria, concern exists that future loads to the bay may place aquatic species at risk if permits are relaxed. Given the more conservative nature of the DOC, it is likely that this model could afford greater protection.

Advisor

Haydn Fox

Subject Categories

Biology | Life Sciences

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