U.S. EPA Contaminated Site Cleanup Information (CLU-IN)

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Mercury is a naturally occurring element and is generally found in nature in ore form. The most prevalent ore form is cinnabar (mercury sulfide). In the United States there are large cinnabar deposits at New Almaden and New Idria, California, and minable deposits in Nevada, Utah, Oregon, Arkansas, Idaho, and Texas. These deposits were mined in the late 1800s and early 1900s, but many had been closed by the mid 1900s. Between 1970 and 1990, all remaining cinnabar mines were closed because of environmental concerns. Abandoned mines can still be a source of contamination. Presently, mercury contamination occurs in the United States from mining and processing of co-located minerals, such as gold.

Inorganic mercury also occurs in small amounts in many rock types such as granite and shale. Although most rocks, sediments, water, and soils naturally contain small but varying amounts of mercury, scientists have found some local mineral occurrences and thermal springs that are naturally high in mercury. Depending on the types of rocks through which water flows, freshwater systems can contain concentrations of mercury as high as 70ppb.

Alkali and metal processing, incineration of coal, incineration of medical and other waste, and mining and processing of gold ore contribute greatly to mercury concentrations in some areas, but atmospheric deposition is the dominant source of mercury over most of the landscape. Natural sources of atmospheric mercury include volcanoes, geologic deposits of mercury, and volatilization from the ocean. Atmospheric mercury levels are measurably higher in the vicinity of active volcanoes than in other areas unaffected by humans. Once in the atmosphere, elemental mercury is widely disseminated and can circulate for years, accounting for its wide-spread distribution.

According to EPA's 1997 mercury study report to Congress, of the estimated 158 tons of mercury emitted annually into the atmosphere by anthropogenic sources in the United States, approximately 87 percent is from combustion point sources, 10 percent is from manufacturing point sources, 2 percent is from area sources, and 1 percent is from miscellaneous sources. Four specific source categories account for approximately 80 percent of the total anthropogenic emissions—coal-fired utility boilers (33 percent), municipal waste combustion (19 percent), commercial/industrial boilers (18 percent), and medical waste incinerators (10 percent). Note that gold mining and processing operations, particularly mines in Nevada, have the ability to emit large quantities of mercury to the atmosphere.

Combustion sources can emit both elemental mercury and ionic mercury. Ionic mercury is water soluble and associates with particulates. Atmospheric deposition of mercury is relatively fast; the mercury usually remains in the atmosphere for one to ten days. When ionic mercury is present as a gas, it is highly water soluble and is deposited as precipitation. Mercury can also bind to particles present in the air and become deposited on land or water as a result of the increased mass. Mercury emitted in elemental form from combustion sources can travel large distances before being deposited on land or water. It can also be transformed into ionic mercury in the atmosphere by the oxidation of elemental mercury by ozone or other oxidants. Mercury deposited in water has the potential to become converted to methylmercury, which is the major mercury species bioaccumulated in fish and other animals.

The areas having the greatest concentration of mercury emissions from anthropogenic sources of total mercury (i.e., all chemical species) are the urban areas in the northeast, the Tampa and Miami areas of Florida, and the larger urban areas of the Midwest, Ohio Valley and Texas. In general, these areas have considerable industrial activity and a large number of coal-fired electrical generation plants. The areas having generally the lowest emissions are in the High Plains region of the central United States. There generally are fewer large emission sources in the western third of the United States, with the exception of the San Francisco and Los Angeles areas and specific industrial operations (e.g., gold mining in Nevada).

Information regarding levels of mercury in specific geographic locations or water bodies may be available in a monitoring or characterization report. Reports on mercury by the USGS are available.

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Background Information on Mercury Sources and Regulations
U.S. EPA Website, 2003.
Contact: Kathryn R. Mahaffey,

Adobe PDF LogoEMMMA: A Web-Based System for Environmental Mercury Mapping, Modeling, and Analysis
Paul P. Hearn, Jr., Stephen P. Wente, David I. Donato, and John J. Aguinaldo.
U.S. Geological Survey Open File Report 2006-1086, 17 pp, 2006

The EMMA website allows interactive use of a nationwide collection of environmental mercury data (fish tissue, atmospheric emissions and deposition, stream sediments, soils, and coal) and mercury-related data (mine locations); predictions of the National Descriptive Model of Mercury in Fish across the United States; and mapping and graphing capabilities to visualize spatial and temporal trends and study relationships between mercury and other variables.

Pilot Survey of Levels of Polychlorinated Dibenzo-p-Dioxins, Polychlorinated Dibenzofurans, Polychlorinated Biphenyls and Mercury in Rural Soils of the United States
U.S. EPA, National Center for Environmental Assessment, Washington, DC. EPA 600-R-05-043F, 308 pp, 2007

Soil samples discussed in this report were collected in 2003 at 27 monitoring stations located in remote areas across the continental United States and Alaska, providing the basis for a study of air/soil relationships by comparison of historical air concentration data with the new soil data. The limited sampling results should not be interpreted as statistically representative of all rural soils in the United States; however, these results might provide a plausible basis for a preliminary characterization of soils in rural/remote areas.

Adobe PDF LogoA National-Scale Assessment of Mercury Bioaccumulation in United States National Parks Using Dragonfly Larvae As Biosentinels through a Citizen-Science Framework
Eagles-Smith, C.A., J.J. Willacker, S.J. Nelson, C.M. Flanagan Pritz, D.P. Krabbenhoft, et al.
Environmental Science & Technology 54(14):8779-8790(2020)

Within a citizen-science network, dragonfly larvae were used as biosentinels to assess Hg bioaccumulation in aquatic ecosystems across >450 sites spanning 100 U.S. National Park Service units. The study examined intrinsic and extrinsic factors associated with variation in Hg concentrations. Relationships were used to develop an integrated impairment index of Hg risk to aquatic ecosystems and found that 12% of site-years exceeded high or severe benchmarks of fish, wildlife, or human health risk.


Adobe PDF LogoContaminants in Aquatic Habitats at Hazardous Waste Sites: Mercury
National Oceanic and Atmospheric Administration, National Ocean Service, Office of Ocean Resources Conservation and Assessment.
NOS ORCA 100, 80 pp., 1996.
Contact: Nancy Beckvar,

Adobe PDF LogoDeposition of Air Pollutants to the Great Waters, Third Report to Congress
U.S. EPA, Office of Air Quality Planning and Standards.
EPA 453-R-00-005, 22 pp., 2000.
Contact: Gail Lacy,

Long-Term Trends in Regional Wet Mercury Deposition and Lacustrine Mercury Concentrations in Four Lakes in Voyageurs National Park
Brigham, M.E., D.D. VanderMeulen, C.A. Eagles-Smith, D.P. Krabbenhoft, R.P. Maki, and J.F. DeWild. | Applied Sciences 11(4):1879(2021)

Adobe PDF LogoMercury Contamination of Aquatic Ecosystems
D.P. Krabbenhoft and D.A. Rickert.
U.S. Geological Survey Fact Sheet FS-216-95, 4 pp., 1995.

Adobe PDF LogoMercury in the Nation's Streams: Levels, Trends, and Implications
Wentz , D.A., M.E. Brigham, L.C. Chasar, M.A. Lutz, and D.P. Krabbenhoft.
U.S. Geological Survey Circular 1395, 100 pp, 2014

Results from USGS studies since the late 1990s provide a comprehensive, multimedia assessment of streams across the United States and yield insights about the importance of watershed characteristics relative to Hg inputs. Information from other environments (lakes, wetlands, soil, atmosphere, glacial ice) also is summarized to help show how Hg varies in space and time.

Adobe PDF LogoProceedings and Summary Report: Workshop on the Fate, Transport, and Transformation of Mercury in Aquatic and Terrestrial Environments
U.S. EPA, Office of Research and Development, and U.S. Geological Survey.
EPA 625-R-02-005, 180 pp., 2002.
Contact: Scott Minamyer,

U.S. Geological Survey National Assessment of Mercury in Aquatic Ecosystems Home Page


Adobe PDF LogoProceedings: National Forum on Mercury in Fish
U.S. EPA, Office of Water.
EPA 823-R-95-002, 278 pp., 1995.
Contact: Bruce Mintz,

Adobe PDF LogoThe National Survey of Mercury Concentrations in Fish, Database Summary 1990-1995
U.S. EPA, Office of Water, 218 pp., 1999.

Adobe PDF LogoA National Pilot Study of Mercury Contamination of Aquatic Ecosystems along Multiple Gradients: Bioaccumulation in Fish
W.G. Brumbaugh, D.P. Krabbenhoft, D.R. Helsel, J.G. Wiener, and K.R. Echols.
U.S. Geological Survey Biological Science Report, USGS/BRD/BSR-2001-0009, 32 pp., 2001.

The overall objective of this survey was to identify ecosystem characteristics that favor the production and bioaccumulation of methylmercury and to compare bioaccumulation rates on a national basis.


All-Time Releases of Mercury to the Atmosphere from Human Activities
Streets, D.G., M.K. Devane, Z. Lu, T.C. Bond, E.M. Sunderland, and D.J. Jacob.
Environmental Science & Technology 45(24):10485-10491(2011)

Researchers reconstructed human additions of mercury to the atmosphere (via the burning of fossil fuels, mining, and industrial processes) using historical data and computer models. Their research shows that mercury emissions peaked during the North American gold and silver rushes in the late 1800s. After a decline in the middle of the 20th century, the levels are rising again, thanks mostly to a surge in coal use. Asia has overtaken Europe and America as the largest contributor of mercury. The researchers predict mercury released from mining and fuel may take as many as 2,000 years to exit the environment and be reincorporated into rocks and minerals in Earth. Longer abstract

Adobe PDF LogoMercury Transport and Fate in Watersheds
U.S. EPA, National Center for Environmental Research.
Star Report, Vol. 4, No. 1, Oct 2000.

Adobe PDF LogoCharacterization of Products Containing Mercury in Municipal Solid Waste in the United States 1970 to 2000: Executive Summary
U.S. EPA, Office of Solid Waste and Emergency Response. EPA 530-S-92-013, 1992.

Adobe PDF LogoCombustion of Hazardous Wastes Containing Arsenic, Lead, and Mercury
U.S. EPA, Office of Solid Waste and Emergency Response. EPA 530-R-94-018, 1994.

Adobe PDF LogoGeochemical Data for Environmental Studies of Mercury Mines in Nevada
John Gray, et al.
U.S. Geological Survey Open-File Report 99-0576, 21 pp., 1999.
Contact: John Gray,

This study aimed to determine if weathering of abandoned mercury mines in Nevada has resulted in any significant effect to surrounding ecosystems. The report describes the methods used for analysis and the geochemical data for samples collected in 1999.

Adobe PDF LogoGeologic Studies of Mercury by the U.S. Geological Survey
John E. Gray, U.S. Geological Survey.
U.S. Geological Survey Circular 1248, 47 pp., 2003.
Contact: John Gray,

Mercury-Added Products Fact Sheets
Northeast Waste Management Officials' Association (NEWMOA), Interstate Mercury Education & Reduction Clearinghouse (IMERC), 2014

Fact sheets on nine types of products summarize data provided by manufacturers and distributors of mercury-added products. The fact sheets cover the amount of mercury used in the products, why mercury has been or continues to be used in the products, who manufactures the products, and other useful information. A tenth fact sheet summarizes the use of mercury across all product categories and includes a trends analysis of mercury use in products from 2001-2010.

Mercury in Massachusetts: an Evaluation of Sources, Emissions, Impacts and Controls
Massachusetts Department of Environmental Protection, 1996.
Contact: Mark Smith,

Adobe PDF LogoMercury in U.S. Coal — Abundance, Distribution, and Modes of Occurrence
Susan J. Tewalt, Linda J. Bragg, and Robert B. Finkelman.
U.S. Geological Survey Fact Sheet 095-01, 4 pp., 2001.
Contact: Susan J. Tewalt,; Robert B. Finkelman,

According to EPA estimates, emissions from coal-fired utilities account for 13 to 26 percent of the total (natural plus anthropogenic) airborne emissions of mercury in the United States.

Mercury Statistics and Information
Contact: William Brooks,

U.S. Geological Survey page for mercury availability and use in commerce.

Adobe PDF LogoMercury Study Report to Congress Volume II: An Inventory of Anthropogenic Mercury Emissions in the United States
U.S. EPA, Office of Air Quality Planning & Standards and Office of Research and Development.
EPA 452-R-97-004, 181 pp., 1997.
Contact: Kathryn R. Mahaffey,

This volume estimates mercury emissions generated by human activities and provides abbreviated process descriptions, control technique options, emission factors, and activity levels for these sources. Where sufficient information is available, locations by city, county, and state are given for point sources.

Adobe PDF LogoMercury Study Report to Congress Volume IV: An Assessment of Exposure to Mercury in the United States
U.S. EPA, Office of Air Quality Planning & Standards and Office of Research and Development.
EPA 452-R-97-004, 293 pp., 1997.
Contact: Kathryn R. Mahaffey,

Using deposition values obtained from fate and transport models, this assessment addresses the exposures that result from selected major anthropogenic combustion and manufacturing sources. This volume also estimates current exposures to the general U.S. population that result from mercury concentrations in freshwater and marine fish.

New Jersey Mercury Task Force Report: Volume III: Sources of Mercury to New Jersey's Environment
New Jersey Department of Environmental Protection.
Contact: Leslie McGeorge, 609-292-1623

Adobe PDF LogoProceedings and Summary Report: Workshop on Mercury in Products, Processes, Waste and the Environment: Eliminating, Reducing and Managing Risks from Non-Combustion Sources
EPA 625-R-00-014, 94 pp., 2001.
Contact: Doug Grosse,

Toxics Release Inventory (TRI) Explorer
U.S. EPA Toxics Release Inventory Program Database.

A search under 'mercury' and 'mercury compounds' for a specific year produces a table that lists the amounts of these contaminants reported to have been disposed of and/or released from various commercial sites (e.g., mining sites, electric power plants) into surface media and the air.

Toolkit for Identification and Quantification of Mercury Releases: Reference Report and Guideline for Inventory Level 2. Version 1.4
United Nations Environment Chemicals Branch, Geneva, Switzerland. 339 pp, 2017

This guide provides detailed descriptions of sources of mercury releases from industrial or other human activity, and identifies mercury input and output factors to enable estimation or quantification of the releases.

Adobe PDF LogoWorkshop on Source Emission and Ambient Air Monitoring of Mercury, September 13-14, 1999, Bloomington, MN
U.S. EPA, Office of Research and Development. EPA 625-R-00-002, 2000.
Contact: Scott Hedges,