Mercury Active
Mercury is a rare, dense metal, slightly more common than gold in the earth's crust. Mercury occurs in several different forms, the most important of which is methylmercury. Methylmercury is the form most readily incorporated into biological tissues and most toxic to humans. Methylmercury accumulates and biomagnifies in the food chain, reaching highest concentrations in predatory fish such as bass and other species which are prized by anglers. Numerous water bodies in California have fish-consumption advisories because of mercury contamination from historical mining. The USGS has collected data and conducted studies in the San Francisco-San Joaquin Delta Estuary, Trinity County, in the Bear, Yuba, and American River watersheds in the Sierra Nevada, and other areas throughout the U.S. On the basis of USGS studies and other recent work, a better understanding is emerging of mercury distribution, ongoing transport, transformation processes, and the extent of biological uptake in areas affected by historical gold mining. This information has been used extensively by federal, state, and local agencies responsible for resource management and public health in California.
Mercury is a rare, dense metal, slightly more common than gold in the earth's crust. It has unusual properties that have made it valuable in metallurgy, electrical systems and chemical processes. It is a liquid at ordinary temperatures and evaporates when exposed to the atmosphere. These unusual physical characteristics, combined with mercury's common use from the beginning of the industrial revolution, have contributed to its widespread dispersion through the atmosphere to land and water around the globe by both wet and dry precipitation. The US EPA estimates that mercury vapor residence time in the atmosphere exceeds one year.
Coal Combustion
Mercury has been recognized as a serious environmental contaminant for many years. As a result, industrial uses have declined significantly over recent decades as effective substitutes have been developed. The US EPA estimates that in the United States the single largest remaining source of mercury discharges into the environment is coal combustion.
Mercury concentrations in coal are generally less than one part per million (ppm), but, in the United States alone in 1995, the large tonnage of coal combustion introduced an estimated 50 tons of mercury into the atmosphere. Mercury released to the environment from oil refined in the United States is approximately 5% of that which may be derived from coal combustion. The total amount of mercury emitted to the atmosphere from coal and oil combustion in North America was about 70 million tons in 2005. A comparable estimate for global mercury emissions from coal and oil combustion is 890 tons, of which 295 tons were emitted in China (Pirrone and others, 2010).
Environmental mercury contamination concerns in California are focused less on atmospheric sources, and more on aquatic sources for several natural and historic reasons.
Mercury Mining
Mercury's discovery in California predates the discovery of gold by several years. The first mines were located in New Almaden, about 10 miles south of present-day San Jose in the Santa Cruz Mountains. The site is now the Almaden Quicksilver County Park, Santa Clara County. The California Coast Ranges went on to be among the most productive mercury districts in the world, with major production centers from New Idria in the south to Clear Lake in the north.
In the Coast Ranges, mercury has been concentrated extensively in natural hydrothermal systems, including active thermal springs that continue to discharge into streams and lakes, and in fossil (inactive) systems that were the sites of commercial mercury mining. The hydrothermal activity contributes to high natural background levels of mercury in parts of the Coast Ranges. The discovery of commercial mercury ore bodies led to the development and operation of numerous mines from the 1840s to the early 1960s, from which more than 220,000,000 pounds of elemental mercury were produced. There were few controls on the dispersion of mercury from these operations, leading to significant increases in environmental mercury concentrations in affected soil, sediment, plants, fish, and other animals. Health advisories on fish consumption because of elevated mercury concentrations are widespread in the Coast Ranges, where more than a dozen separate water bodies are affected, including San Francisco Bay, Lake Berryessa, and Clear Lake.
Mercury Contamination from Historical Gold Mining in California
The 1848 discovery of gold in the Sierra Nevada created a ready market for mercury produced by the mines in California's Coast Ranges. Mercury forms a relatively insoluble amalgam with gold, and miners used this property to increase gold recovery. Millions of pounds of mercury were used, especially in hydraulic placer mining operations that displaced and processed more than 1.5 billion cubic yards of gold-bearing sediments in the Sierra Nevada. Gold- bearing sediments were washed through sluice boxes over mercury that was loosely held in riffles and troughs. Coarse gold was trapped primarily by gravity separation, while the recovery of fine-grained gold was achieved largely with mercury. An estimated 10 to 30 percent of the mercury was lost to the environment in this process and transported into streams and reservoirs along with the discharged sediments (tailings or "slickens") from the hydraulic mining operations.
In many gold-mining areas where mercury was used, it is still relatively easy to find quantities of liquid elemental mercury in sediments and stream channels. Of even greater environmental concern is the presence of methylmercury, an organic form of mercury that is a potent neurotoxin and is especially detrimental to developing fetuses and children. Methylmercury accumulates and biomagnifies in the food chain, reaching highest concentrations in predatory fish such as bass and other species which are prized by anglers. Numerous water bodies in California have fish-consumption advisories because of mercury contamination from historical mining. Several of these advisories are based on data collected by the USGS, including those in Trinity County, and in the Bear, Yuba, and American River watersheds in the Sierra Nevada. For information on these advisories, see the web site of the California Office of Environmental Health Hazard Assessment.
Mercury from hydraulic mining has been transported with sediments downstream into the San Francisco Bay/Sacramento-San Joaquin Delta estuary, where it has contributed to elevated mercury concentrations in fish, resulting in additional consumption advisories and regulatory action through the Total Maximum Daily Load (TMDL) process. For information on the TMDL process see the web sites of the California Regional Water Quality Control Boards:
San Francisco Bay Mercury TMDL
Sacramento - San Joaquin Delta Methylmercury TMDL
Ongoing studies by USGS are focused on characterizing and quantifying sources of mercury and methylmercury to the Bay-Delta, including continuing runoff from mercury mining areas in the Coast Ranges and from gold-mining areas in the Sierra Nevada, and from resuspension and diffusive transport from mercury-contaminated sediments already in the rivers and reservoirs in the Bay-Delta watershed.
Below are other science projects associated with this project.
Lower American River Mercury
Wildfire Effect on Mercury Levels in Putah and Cache Creek Watersheds
Analysis of Factors Causing Mercury Impairment in Water Bodies of the Sierra Nevada, California
Below are publications associated with this project.
Mercury contamination from historical gold mining in California
Concurrent photolytic degradation of aqueous methylmercury and dissolved organic matter
Mercury cycling in agricultural and managed wetlands, Yolo Bypass, California: Spatial and seasonal variations in water quality
Mercury cycling in agricultural and managed wetlands: a synthesis of methylmercury production, hydrologic export, and bioaccumulation from an integrated field study
Methylmercury production in and export from agricultural wetlands in California, USA: the need to account for physical transport processes into and out of the root zone
The effects of sediment and mercury mobilization in the South Yuba River and Humbug Creek confluence area, Nevada County, California: Concentrations, speciation, and environmental fate – Part 1: Field characterization
The effects of sediment and mercury mobilization in the South Yuba River and Humbug Creek confluence area, Nevada County, California: Concentrations, speciation and environmental fate - Part 2: Laboratory Experiments
Methylmercury cycling, bioaccumulation, and export from agricultural and non-agricultural wetlands in the Yolo Bypass
Mercury concentrations in fish from a Sierra Nevada foothill reservoir located downstream from historic gold-mining operations
Mercury, methylmercury, and other constituents in sediment and water from seasonal and permanent wetlands in the Cache Creek settling basin and Yolo Bypass, Yolo County, California, 2005-06
Environmental factors affecting mercury in Camp Far West Reservoir, California, 2001-03
Ecosystem conceptual model- Mercury
Influence of plankton mercury dynamics and trophic pathways on mercury concentrations of top predator fish of a mining-impacted reservoir
Below are news stories associated with this project.
Below are partners that we have worked with on California mercury studies.
- Overview
Mercury is a rare, dense metal, slightly more common than gold in the earth's crust. Mercury occurs in several different forms, the most important of which is methylmercury. Methylmercury is the form most readily incorporated into biological tissues and most toxic to humans. Methylmercury accumulates and biomagnifies in the food chain, reaching highest concentrations in predatory fish such as bass and other species which are prized by anglers. Numerous water bodies in California have fish-consumption advisories because of mercury contamination from historical mining. The USGS has collected data and conducted studies in the San Francisco-San Joaquin Delta Estuary, Trinity County, in the Bear, Yuba, and American River watersheds in the Sierra Nevada, and other areas throughout the U.S. On the basis of USGS studies and other recent work, a better understanding is emerging of mercury distribution, ongoing transport, transformation processes, and the extent of biological uptake in areas affected by historical gold mining. This information has been used extensively by federal, state, and local agencies responsible for resource management and public health in California.
Mercury is a rare, dense metal, slightly more common than gold in the earth's crust. It has unusual properties that have made it valuable in metallurgy, electrical systems and chemical processes. It is a liquid at ordinary temperatures and evaporates when exposed to the atmosphere. These unusual physical characteristics, combined with mercury's common use from the beginning of the industrial revolution, have contributed to its widespread dispersion through the atmosphere to land and water around the globe by both wet and dry precipitation. The US EPA estimates that mercury vapor residence time in the atmosphere exceeds one year.
Coal Combustion
Mercury has been recognized as a serious environmental contaminant for many years. As a result, industrial uses have declined significantly over recent decades as effective substitutes have been developed. The US EPA estimates that in the United States the single largest remaining source of mercury discharges into the environment is coal combustion.
Mercury concentrations in coal are generally less than one part per million (ppm), but, in the United States alone in 1995, the large tonnage of coal combustion introduced an estimated 50 tons of mercury into the atmosphere. Mercury released to the environment from oil refined in the United States is approximately 5% of that which may be derived from coal combustion. The total amount of mercury emitted to the atmosphere from coal and oil combustion in North America was about 70 million tons in 2005. A comparable estimate for global mercury emissions from coal and oil combustion is 890 tons, of which 295 tons were emitted in China (Pirrone and others, 2010).
Environmental mercury contamination concerns in California are focused less on atmospheric sources, and more on aquatic sources for several natural and historic reasons.
Mercury Mining
Mercury's discovery in California predates the discovery of gold by several years. The first mines were located in New Almaden, about 10 miles south of present-day San Jose in the Santa Cruz Mountains. The site is now the Almaden Quicksilver County Park, Santa Clara County. The California Coast Ranges went on to be among the most productive mercury districts in the world, with major production centers from New Idria in the south to Clear Lake in the north.
In the Coast Ranges, mercury has been concentrated extensively in natural hydrothermal systems, including active thermal springs that continue to discharge into streams and lakes, and in fossil (inactive) systems that were the sites of commercial mercury mining. The hydrothermal activity contributes to high natural background levels of mercury in parts of the Coast Ranges. The discovery of commercial mercury ore bodies led to the development and operation of numerous mines from the 1840s to the early 1960s, from which more than 220,000,000 pounds of elemental mercury were produced. There were few controls on the dispersion of mercury from these operations, leading to significant increases in environmental mercury concentrations in affected soil, sediment, plants, fish, and other animals. Health advisories on fish consumption because of elevated mercury concentrations are widespread in the Coast Ranges, where more than a dozen separate water bodies are affected, including San Francisco Bay, Lake Berryessa, and Clear Lake.
Mercury Contamination from Historical Gold Mining in California
The 1848 discovery of gold in the Sierra Nevada created a ready market for mercury produced by the mines in California's Coast Ranges. Mercury forms a relatively insoluble amalgam with gold, and miners used this property to increase gold recovery. Millions of pounds of mercury were used, especially in hydraulic placer mining operations that displaced and processed more than 1.5 billion cubic yards of gold-bearing sediments in the Sierra Nevada. Gold- bearing sediments were washed through sluice boxes over mercury that was loosely held in riffles and troughs. Coarse gold was trapped primarily by gravity separation, while the recovery of fine-grained gold was achieved largely with mercury. An estimated 10 to 30 percent of the mercury was lost to the environment in this process and transported into streams and reservoirs along with the discharged sediments (tailings or "slickens") from the hydraulic mining operations.
In many gold-mining areas where mercury was used, it is still relatively easy to find quantities of liquid elemental mercury in sediments and stream channels. Of even greater environmental concern is the presence of methylmercury, an organic form of mercury that is a potent neurotoxin and is especially detrimental to developing fetuses and children. Methylmercury accumulates and biomagnifies in the food chain, reaching highest concentrations in predatory fish such as bass and other species which are prized by anglers. Numerous water bodies in California have fish-consumption advisories because of mercury contamination from historical mining. Several of these advisories are based on data collected by the USGS, including those in Trinity County, and in the Bear, Yuba, and American River watersheds in the Sierra Nevada. For information on these advisories, see the web site of the California Office of Environmental Health Hazard Assessment.
Mercury from hydraulic mining has been transported with sediments downstream into the San Francisco Bay/Sacramento-San Joaquin Delta estuary, where it has contributed to elevated mercury concentrations in fish, resulting in additional consumption advisories and regulatory action through the Total Maximum Daily Load (TMDL) process. For information on the TMDL process see the web sites of the California Regional Water Quality Control Boards:
San Francisco Bay Mercury TMDL
Sacramento - San Joaquin Delta Methylmercury TMDL
Ongoing studies by USGS are focused on characterizing and quantifying sources of mercury and methylmercury to the Bay-Delta, including continuing runoff from mercury mining areas in the Coast Ranges and from gold-mining areas in the Sierra Nevada, and from resuspension and diffusive transport from mercury-contaminated sediments already in the rivers and reservoirs in the Bay-Delta watershed.
- Science
Below are other science projects associated with this project.
Filter Total Items: 15Lower American River Mercury
Dredging operations for gold along the American River began in the 1860s and continued through the early part of the 20th century, ending about 1962. More than one billion cubic yards of gravel were dredged, making the American River dredge field the second largest in California.Wildfire Effect on Mercury Levels in Putah and Cache Creek Watersheds
A serious consequence of wildfires is the erosion which occurs during storm events in areas where vegetation has been burned away. In cases where such land is near a creek or stream, mercury (Hg) and other contaminants from the eroding soil can make their way into the waterways, impacting the health of fish and wildlife, and the quality of the water supply for local communities (see: USGS Fact...Analysis of Factors Causing Mercury Impairment in Water Bodies of the Sierra Nevada, California
The SWRCB has requested assistance from the USGS in analyzing the factors that control Hg concentrations in fish tissue in the Sierra Nevada. Specifically, the SWRCB wants to know whether Hg and (or) MeHg in bed sediment and (or) suspended sediment could be potentially useful in the future as a 303(d) listing criteria. The SWRCB has requested that the USGS perform an analysis of existing data for... - Publications
Below are publications associated with this project.
Mercury contamination from historical gold mining in California
Mercury contamination from historical gold mines represents a potential risk to human health and the environment. This fact sheet provides background information on the use of mercury in historical gold mining and processing operations in California, with emphasis on historical hydraulic mining areas. It also describes results of recent USGS projects that address the potential risks associated witAuthorsCharles N. Alpers, Michael P. Hunerlach, Jason T. May, Roger L. HothemFilter Total Items: 38Concurrent photolytic degradation of aqueous methylmercury and dissolved organic matter
Monomethyl mercury (MeHg) is a potent neurotoxin that threatens ecosystem viability and human health. In aquatic systems, the photolytic degradation of MeHg (photodemethylation) is an important component of the MeHg cycle. Dissolved organic matter (DOM) is also affected by exposure to solar radiation (light exposure) leading to changes in DOM composition that can affect its role in overall mercuryAuthorsJacob A. Fleck, Gary W. Gill, Brian A. Bergamaschi, Tamara E.C. Kraus, Bryan D. Downing, Charles N. AlpersMercury cycling in agricultural and managed wetlands, Yolo Bypass, California: Spatial and seasonal variations in water quality
The seasonal and spatial variability of water quality, including mercury species, was evaluated in agricultural and managed, non-agricultural wetlands in the Yolo Bypass Wildlife Area, an area managed for multiple beneficial uses including bird habitat and rice farming. The study was conducted during an 11-month period (June 2007 to April 2008) that included a summer growing season and flooded conAuthorsCharles N. Alpers, Jacob A. Fleck, Mark C. Marvin-DiPasquale, Craig A. Stricker, Mark Stephenson, Howard E. TaylorMercury cycling in agricultural and managed wetlands: a synthesis of methylmercury production, hydrologic export, and bioaccumulation from an integrated field study
With seasonal wetting and drying, and high biological productivity, agricultural wetlands (rice paddies) may enhance the conversion of inorganic mercury (Hg(II)) to methylmercury (MeHg), the more toxic, organic form that biomagnifies through food webs. Yet, the net balance of MeHg sources and sinks in seasonal wetland environments is poorly understood because it requires an annual, integrated asseAuthorsLisamarie Windham-Myers, Jacob A. Fleck, Joshua T. Ackerman, Mark C. Marvin-DiPasquale, Craig A. Stricker, Wesley A. Heim, Philip A.M. Bachand, Collin A. Eagles-Smith, Gary Gill, Mark Stephenson, Charles N. AlpersMethylmercury production in and export from agricultural wetlands in California, USA: the need to account for physical transport processes into and out of the root zone
Concentration and mass balance analyses were used to quantify methylmercury (MeHg) loads from conventional (white) rice, wild rice, and fallowed fields in northern California's Yolo Bypass. These analyses were standardized against chloride to distinguish transport pathways and net ecosystem production (NEP). During summer, chloride loads were both exported with surface water and moved into the rooAuthorsPhilip A.M. Bachand, Sandra M. Bachand, Jacob A. Fleck, Charles N. Alpers, Mark Stephenson, Lisamarie Windham-MyersThe effects of sediment and mercury mobilization in the South Yuba River and Humbug Creek confluence area, Nevada County, California: Concentrations, speciation, and environmental fate – Part 1: Field characterization
Millions of pounds of mercury (Hg) were deposited in the river and stream channels of the Sierra Nevada from placer and hard-rock mining operations in the late 1800s and early 1900s. The resulting contaminated sediments are relatively harmless when buried and isolated from the overlying aquatic environment. The entrained Hg in the sediment constitutes a potential risk to human and ecosystem healthAuthorsJacob A. Fleck, Charles N. Alpers, Mark Marvin-DiPasquale, Roger L. Hothem, Scott A. Wright, Kevin Ellett, Elizabeth Beaulieu, Jennifer L. Agee, Evangelos Kakouros, Le H. Kieu, Dennis D. Eberl, Alex E. Blum, Jason T. MayThe effects of sediment and mercury mobilization in the South Yuba River and Humbug Creek confluence area, Nevada County, California: Concentrations, speciation and environmental fate - Part 2: Laboratory Experiments
No abstract available.AuthorsMark Marvin-DiPasquale, Jennifer L. Agee, Eangelos Kakouros, Le H. Kieu, Jacob A. Fleck, Charles N. AlpersMethylmercury cycling, bioaccumulation, and export from agricultural and non-agricultural wetlands in the Yolo Bypass
This 18-month field study addresses the seasonal and spatial patterns and processes controlling methylmercury (MeHg) production, bioaccumulation, and export from natural and agricultural wetlands of the Yolo Bypass Wildlife Area (YBWA). The data were collected in conjuntion with a Proposition 40 grant from the State Water Resources Control Board in support of the development of Best Management PraAuthorsLisamarie Windham-Myers, Mark Marvin-DiPasquale, Jacob Fleck, Charles N. Alpers, Joshua T. Ackerman, Collin A. Eagles-Smith, Craig Stricker, Mark Stephenson, David Feliz, Gary Gill, Philip Bachand, Ann Brice, Robin KulakowMercury concentrations in fish from a Sierra Nevada foothill reservoir located downstream from historic gold-mining operations
This study examined mercury concentrations in whole fish from Camp Far West Reservoir, an 830-ha reservoir in northern California, USA, located downstream from lands mined for gold during and following the Gold Rush of 1848–1864. Total mercury (reported as dry weight concentrations) was highest in spotted bass (mean, 0.93 μg/g; range, 0.16–4.41 μg/g) and lower in bluegill (mean, 0.45 μg/g; range,AuthorsMichael K. Saiki, Barbara A. Martin, Thomas W. May, Charles N. AlpersMercury, methylmercury, and other constituents in sediment and water from seasonal and permanent wetlands in the Cache Creek settling basin and Yolo Bypass, Yolo County, California, 2005-06
This report presents surface water and surface (top 0-2 cm) sediment geochemical data collected during 2005-2006, as part of a larger study of mercury (Hg) dynamics in seasonal and permanently flooded wetland habitats within the lower Sacramento River basin, Yolo County, California. The study was conducted in two phases. Phase I represented reconnaissance sampling and included three locations withAuthorsMark Marvin-DiPasquale, Charles N. Alpers, Jacob A. FleckEnvironmental factors affecting mercury in Camp Far West Reservoir, California, 2001-03
This report documents water quality in Camp Far West Reservoir from October 2001 through August 2003. The reservoir, located at approximately 300 feet above sea level in the foothills of the northwestern Sierra Nevada, California, is a monomictic lake characterized by extreme drawdown in the late summer and fall. Thermal stratification in summer and fall is coupled with anoxic conditions in the hyAuthorsCharles N. Alpers, A. Robin Stewart, Michael K. Saiki, Mark C. Marvin-DiPasquale, Brent R. Topping, Kelly M. Rider, Steven K. Gallanthine, Cynthia A. Kester, Robert O. Rye, Ronald C. Antweiler, John F. De WildEcosystem conceptual model- Mercury
Mercury has been identified as an important contaminant in the Delta, based on elevated concentrations of methylmercury (a toxic, organic form that readily bioaccumulates) in fish and wildlife. There are health risks associated with human exposure to methylmercury by consumption of sport fish, particularly top predators such as bass species. Original mercury sources were upstream tributaries whereAuthorsCharles N. Alpers, Collin A. Eagles-Smith, Chris Foe, Susan Klasing, Mark C. Marvin-DiPasquale, Darell Slotton, Lisamarie Windham-MyersInfluence of plankton mercury dynamics and trophic pathways on mercury concentrations of top predator fish of a mining-impacted reservoir
Physical and biogeochemical characteristics of the aquatic environment that affect growth dynamics of phytoplankton and the zooplankton communities that depend on them may also affect uptake of methylmercury (MeHg) into the pelagic food web of oligotrophic reservoirs. We evaluated changes in the quality and quantity of suspended particulate material, zooplankton taxonomy, and MeHg concentrations cAuthorsA.R. Stewart, M. K. Saiki, J.S. Kuwabara, Charles N. Alpers, M. Marvin-DiPasquale, D. P. Krabbenhoft - News
Below are news stories associated with this project.
- Partners
Below are partners that we have worked with on California mercury studies.
Filter Total Items: 13