Records of contaminant input to San Francisco Bay
- Geological Survey, Menlo Park, CA (United States)
- Univ. of California, Santa Cruz, CA (United States). Inst. of Marine Science
- Univ. of California, Los Angeles, CA (United States). Inst. of Geophysics and Planetary Physics
- Texas A and M Univ., Galveston, TX (United States)
San Francisco Bay, one of the few large estuaries on the West Coast of North America, was subjected to great change as mining, agriculture, industrialization and urbanization accelerated after 1849, and river flows were diverted for agriculture. Trends in contamination were evident in sediment cores analyzed from seven sites. Sedimentation rates increased with human activities. Industrialization was a greater source of contamination than mining. Nearest the mouth of the estuary, concentrations of Hg, Cu, Zn, Pb and PAH began to increase around 1900. Isotopes of Pb indicated sediments were affected by a mixture of atmospheric, industrial and erosional inputs. Peaks in some contaminants were evident since the 1950s, notably Ag, Cd in water (as recorded in foraminifers tests), and DDT. Chromium and vanadium were naturally enriched throughout the cores. Declines in metal concentrations in surface sediments were not evident. Vertical mixing could delay response of sediments to changed metal inputs. Nearer the head of the estuary, contaminant concentrations, TOC and indicators of terrigenous carbon increased sharply where {sup 137}Cs and {sup 239,240} Pu was present (presumably post-1950). Diversion of river flows may have affected accumulation of sediments contaminated by post-war industrialization and acceleration of agricultural development.
- OSTI ID:
- 40058
- Report Number(s):
- CONF-9410273--
- Country of Publication:
- United States
- Language:
- English
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