U.S. Geological Survey Open-File Report 2004-1213
This report is available as a pdf.
Trace element concentrations were analyzed on samples of fine-grained sediments and clams (Macoma balthica) collected from a mudflat one kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant in South San Francisco Bay. This report serves as a continuation of the Near Field Receiving Water Monitoring Study, which was started in 1994. The data for 2003, herein, are interpreted within that context. Metal concentrations in both sediments and clam tissue samples have been within the range of values produced by seasonal variability; however, copper and zinc, display continued decreases over the last decade. In 2003, copper in sediment was observed to drop below the ERL (Effects Range-Low) concentration for the third consecutive year and zinc concentrations never exceeded the ERL. Yearly average concentrations of copper, zinc and silver in Macoma balthica for 2003 are some of the lowest recorded since monitoring began in 1975. Mercury and selenium concentrations in sediments and clams at Palo Alto were similar to concentrations observed elsewhere in the San Francisco Bay.
Table of contents
List of figures
List of tables
Results and Discussion
For additional information write to:
Samuel N. Luoma,
U.S. Geological Survey
345 Middlefield Road
Menlo Park, CA 94025
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Box 25286, Denver Federal Center
Denver, CO 80225
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