The Bay-Delta has a long list of contaminants of concern, including naturally occurring trace metals such as mercury and selenium.
Mercury, a highly toxic heavy metal, was used extensively to extract gold from hydraulic mining in the Sierra Nevada and the Klamath-Trinity Mountains starting in the mid-1800s. Although large-scale hydraulic mining ended by the early 1900s, mercury-laden sediments, carried by rivers draining these mountains, are still found throughout the Bay-Delta. Selenium, a trace element found in sediments and rocks, is recognized as an important stressor in aquatic environments because of its potency as a reproductive toxin and its tendency to accumulate through food webs. USGS studies mercury and selenium quantities, locations, and characteristics in the Bay-Delta to understand the mechanisms of transport of mercury and selenium within sediment and their uptake by fish, birds, and other wildlife, as well as the effects on human health.
For more information see:
Trace Metals in San Francisco Bay Clams
Linking Selenium Sources to Ecosystems: Local and Global Perspectives
Linking Selenium Sources to Ecosystems: Irrigation
Linking Selenium Sources to Ecosystems: Refining
Mercury and Dissolved Organic Matter in Delta Wetlands
Contaminants in Waterbirds and Effects on Avian Reproduction
Mercury Bioaccumulation in Wetlands
Back to San Francisco Bay-Delta Science
The Bay-Delta has a long list of contaminants of concern, including naturally occurring trace metals such as mercury and selenium.
Mercury, a highly toxic heavy metal, was used extensively to extract gold from hydraulic mining in the Sierra Nevada and the Klamath-Trinity Mountains starting in the mid-1800s. Although large-scale hydraulic mining ended by the early 1900s, mercury-laden sediments, carried by rivers draining these mountains, are still found throughout the Bay-Delta. Selenium, a trace element found in sediments and rocks, is recognized as an important stressor in aquatic environments because of its potency as a reproductive toxin and its tendency to accumulate through food webs. USGS studies mercury and selenium quantities, locations, and characteristics in the Bay-Delta to understand the mechanisms of transport of mercury and selenium within sediment and their uptake by fish, birds, and other wildlife, as well as the effects on human health.
For more information see:
Trace Metals in San Francisco Bay Clams
Linking Selenium Sources to Ecosystems: Local and Global Perspectives
Linking Selenium Sources to Ecosystems: Irrigation
Linking Selenium Sources to Ecosystems: Refining
Mercury and Dissolved Organic Matter in Delta Wetlands
Contaminants in Waterbirds and Effects on Avian Reproduction
Mercury Bioaccumulation in Wetlands
Back to San Francisco Bay-Delta Science