Monitoring Trace Metals and the Benthic Community Near the Palo Alto Water Quality Control Plant in South San Francisco Bay, California

Introduction
Anthropogenic releases of metals into the environment can adversely impact aquatic ecosystems. Sampling sediments and benthic organisms is a common method used to evaluate impacts and determine spatial distributions and temporal trends of metal contamination.

The concentrations of metals in sediments serve as a record of metal exposure. Fluctuations in the record may indicate changes in anthropogenic releases of metals into the environment. Metals in sediments are also an indicator of the degree of metal exposure of benthic animals in contact with bottom sediments and suspended particulates. However, sediment concentrations do not provide the most accurate picture. . Instead the record of tissue metal concentrations can be a more sensitive indicator of of anthoropogenic inputs and ecological exposure.

A common method of monitoring the effects of contaminants in aquatic systems is to examine the benthic community structure. Contaminants can adversely impact benthic organisms at several organizational levels. Linkages between contaminant exposures and changes at the population or community level can be used to create a time-integrated picture of ecosystem response to contaminant loading.

This study presents trace metal and benthic community data for an inshore location in South San Francisco Bay. This location lies in the vacinity of the discharge from the Palo Alto Regional Water Quality Control Plant (map). Trace metal concentrations were observed in sediments and clams. In conjunction with metal analysis, data was collected to evaluate the structure of the benthic community over time. The data generated is used to approach the following objectives:

• Provide data to assess seasonal and year-to-year trends in trace element concentrations in sediments and clams in receiving waters near the Palo Alto Regional Water Quality Control Plant (RWQCP) as designated in the RWQCB's Self-Monitoring Program guidelines.
• Present the data within the context of historical changes inshore in South Bay and within the context of other locations in San Francisco Bay published in the international literature.
• Coordinate inshore receiving water monitoring programs for Palo Alto and provide data compatible with relevant aspects of the Regional Monitoring Program. The near field data will augment the Regional Monitoring Program as suggested by the RWQCB.
• Provide data which could support other South San Francisco Bay issues or programs such as development of sediment quality standards.

Download data

Metal concentrations in sediments 1977-2003

• PA77-04sed.xls (117kb) - Microsoft Excel spreadsheet
• PA77-04sed.txt (35kb) - Tab delimited text file
• PA77-04sed.pdf (39kb) - Adobe Acrobat pdf format

Metal concentrations in clams 1977-2003

• PA77-04clam.xls (91kb) - Microsoft Excel spreadsheet
• PA77-04clam.txt (30kb) - Tab delimited text file
• PA77-04clam.pdf (36kb) - Adobe Acrobat pdf format

Further reading
Executive summary of findings through 2003 (Adobe pdf, 60K)

Linking Bioaccumulation and Biological Effects to Pollutant Loads in South San Francisco Bay

Poster Presentation: Metals in San Francisco Bay: Response to Decreases In Point Source Loads and Environmental Factors (adobe pdf, 200K)

Related Websites
California Environmental Protection Agency

California State Regional Water Quality Control Board

Palo Alto Water Quality Control Plant

Palo Alto Baylands Nature Preserve

References
Lorenzi, A.H., Cain, D. J., Parchaso, F. Thompson, J.K., Luoma, S.N., Hornberger, M.I., Dyke, J.L. Dyke, Cervantes, R., and Shouse, M. K. 2007. Near-Field Receiving Water Monitoring of Trace Metals and a Benthic Community Near the Palo Alto Regional Water Quality Control Plant in South San Francisco Bay, California: 2006. U.S. Geological Survey Open File Report 2007-1199. Menlo Park, California. 128pp

Cain, D. J., Parchaso, F. Thompson, J.K., Luoma, S.N., Lorenzi, A.H., Moon, E., Shouse, M. K., Hornberger, M.I., and J.L. Dyke. 2006. Near-Field Receiving Water Monitoring of Trace Metals and a Benthic Community Near the Palo Alto Regional Water Quality Control Plant in South San Francisco Bay, California: 2005. U.S. Geological Survey Open File Report 2006-1152. Menlo Park, California. 128pp.

Edward Moon,Samuel N. Luoma, Daniel J. Cain, Michelle I. Hornberger and Carlos Primo C. David, 2004, Near Field Receiving Water Monitoring of Trace Metals in Clams (Macoma Balthica) and Sediments near the Palo Alto Water Quality Control Plant in South San Francisco Bay: 2003. U.S. Geological Survey Open File Report 2004-1213. Menlo Park, California. 84pp.

Michelle K Shouse, Parchaso, Francis and Thompson, Janet K. 2004 Near-field receiving water monitoring of a benthic community near the Palo Alto Water Quality Control Plant in South San Francisco Bay: February 1974 through December 2003. U.S. Geological Survey Open File Report 2004-1210. Menlo Park, California. 39pp.

Edward Moon, Carlos Primo C. David, Samuel N. Luoma, Daniel J. Cain, Michelle I. Hornberger and Irene R. Lavigne 2003, Near Field Receiving Water Monitoring of Trace Metals in Clams (Macoma Balthica) and Sediments near the Palo Alto Water Quality Control Plant in South San Francisco Bay: 2002. U.S. Geological Survey Open File Report 03-339. Menlo Park, California. 78pp.

Michelle K Shouse, Parchaso, Francis and Thompson, Janet K. 2003 Near-field receiving water monitoring of a benthic community near the Palo Alto Water Quality Control Plant in South San Francisco Bay: February 1974 through December 2002. U.S. Geological Survey Open File Report 2003-224. Menlo Park, California. 41pp.

Carlos Primo C. David, Samuel N. Luoma, Cynthia L. Brown, Daniel J. Cain, Michelle I. Hornberger and Irene R. Lavigne 2002, Near Field Receiving Water Monitoring of Trace Metals in Clams (Macoma Balthica) and Sediments Near the Palo Alto Water Quality Control Plant in South San Francisco Bay, California: 1999-2001. US. Geological Survey Open File Report 02-453. Menlo Park, California. 50pp.