Records of contaminant input to San Francisco Bay
- Geological Survey, Menlo Park, CA (United States)
- Univ. of California, Santa Cruz, CA (United States)
- Univ. of California, Los Angeles, CA (United States)
- Texas A and M Univ., Galveston, TX (United States)
Trends in contamination in the sediments of San Francisco Bay have been affected by hydrologic disturbances as well as mining, agriculture, industrialization and urbanization. Agricultural development and hydraulic mining for gold changed sedimentation rates in the 1800`s, and diluted pollutant concentrations in sediments. The estuary became a more efficient trap for contaminants in 1930--1950. Rivers released the last of the diluent sediments deposited by hydraulic mining, water projects began diverting a sizable proportion of river flow away from the Bay and residence time for SPM increased. Urban and industrial growth also accelerated in the 1940--50`s. In 1950 the mixture of contaminants in the Bay sediments was dominated by high concentrations of mercury and PAH`S. By 1970, high concentrations of Ag, Cu, Zn, Pb, DDT and PCB`s were added to that mixture. After investments in waste treatment began increasing, concentrations of most contaminants declined. The proportionate mixture of the different contaminants also changed. Concentrations of PAH`s and some metals (Se, Cu, Zn) have been least affected by improved waste treatment; residues of other contaminants continue to recycle within the Bay. Inputs of modern pesticides (e.g. diazanon) occur in episodes that are superimposed upon the historical and modern chronic contamination in the estuary. Waste treatment has been very successful in reducing contamination in San Francisco Bay, but significant problems remain unsolved.
- OSTI ID:
- 203587
- Report Number(s):
- CONF-9511137--; ISBN 1-880611-03-1
- Country of Publication:
- United States
- Language:
- English
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