Mercury is a potent neurotoxin that can affect the human nervous system. Eating fish contaminated with mercury can cause serious harm to people and wildlife.
BACKGROUND
Mercury is a potent neurotoxin that can accumulate in fish to levels of concern for human health and the health of fish-eating wildlife. Mercury contamination of fish is the primary reason for issuing fish consumption advisories, which exist in every State in the Nation. Much of the mercury in the environment originates from combustion of coal and can travel long distances in the atmosphere before being deposited on the land surface. As a result, mercury can bioaccumulate in fish in areas with no obvious source of mercury pollution.1
Mercury is the leading cause of impairment in the Nation's estuaries and lakes and was cited in nearly 80 percent of all reported fish-consumption advisories.2 The geographic extent of mercury advisories covers more than 10 million acres of lakes and more than 400,000 stream miles.3
The fact sheet Mercury Contamination of Aquatic Ecosystems answers many of the basic questions about mercury. For a deeper dive into the topic, download the USGS Circular 1395, highlighted below.
FACTS ABOUT MERCURY
- Highly toxic to the nervous system
- Persistent in the environment
- Bioaccumulates (higher concentrations in tissues of aquatic plants and animals than in water)
- Biomagnifies (higher concentrations at increasingly higher levels in the food chain)
- Numerous chemical forms in air, water, sediment, and biota
UNDERSTANDING THE MERCURY CYCLE
Mercury contamination is global and affects many waters that have no obvious mercury source. This is because mercury emissions generally disperse widely in the atmosphere before being deposited to the earth's surface. Mercury is emitted by natural sources, such as volcanoes, geothermal springs, geologic deposits, and the ocean. Human-related sources primarily include coal combustion, waste incineration, industrial uses, and mining. During the last 150 years, human activities have more than doubled natural amounts of mercury in the atmosphere.4
In natural waters, inorganic mercury is generally not a health concern. The real issue is methylmercury, an organic form that is highly toxic to the nervous system. Methylmercury is produced from inorganic mercury by methylation, a microbial process that is controlled by certain bacteria and enhanced by chemical and environmental variables, such as the presence of organic matter and the absence of oxygen. More than 95 percent of all mercury in fish is methylmercury, and this form of mercury biomagnifies to high concentrations at the top of food chains.5
RELATED USGS RESEARCH
- Mercury in the Environment
- USGS Mercury Research Laboratory
- Mercury in Aquatic Ecosystems
- Mercury Statistics and Information
ADDITIONAL RESOURCES
U.S. Environmental Protection Agency
Use the links below to access web pages describing additional USGS research on mercury and associated topics
Metals and Other Trace Elements
Water-Quality Trends From Lake Cores
Sediment-Associated Contaminants
Stream Ecology
Mercury Cycling and Effects on Ecological Communities
Habitat and Land-Use Influences on Contaminant Bioaccumulation
Contaminant Bioaccumulation through Food Webs
Access USGS reports and publications on mercury and water quality. For more publications on mercury, search the USGS Publications Warehouse. Look here for help using the Pubs Warehouse.
Mercury contamination of aquatic ecosystems
Chemical and physical controls on mercury source signatures in stream fish from the northeastern United States
Topics in coal geochemistry—Short course
External quality assurance project report for the National Atmospheric Deposition Program’s National Trends Network and Mercury Deposition Network, 2015–16
Spatial patterns and temporal changes in atmospheric-mercury deposition for the midwestern USA, 2001–2016
Lake levels and water quality in comparison to fish mercury body burdens, Voyageurs National Park, Minnesota, 2013–15
Optimizing fish sampling for fish - mercury bioaccumulation factors
Effects of urbanization on mercury deposition and accumulation in New England
Mercury in the nation's streams - Levels, trends, and implications
An empirical approach to modeling methylmercury concentrations in an Adirondack stream watershed
Mercury bioaccumulation in estuarine wetland fishes: Evaluating habitats and risk to coastal wildlife
Methylmercury-induced changes in gene transcription associated with neuroendocrine disruption in largemouth bass (Micropterus salmoides)
Mercury in the soil of two contrasting watersheds in the eastern United States
Use the links below to find news stories on USGS research on mercury and water quality.
Isotopic tracers in fish in Northeast provide clue to mercury sources
Isotopes of mercury in fish can indicate the source of that mercury, reports a new study from the USGS Regional Stream Quality Assessment.
- Overview
Mercury is a potent neurotoxin that can affect the human nervous system. Eating fish contaminated with mercury can cause serious harm to people and wildlife.
BACKGROUND
Mercury is a potent neurotoxin that can accumulate in fish to levels of concern for human health and the health of fish-eating wildlife. Mercury contamination of fish is the primary reason for issuing fish consumption advisories, which exist in every State in the Nation. Much of the mercury in the environment originates from combustion of coal and can travel long distances in the atmosphere before being deposited on the land surface. As a result, mercury can bioaccumulate in fish in areas with no obvious source of mercury pollution.1
Mercury is the leading cause of impairment in the Nation's estuaries and lakes and was cited in nearly 80 percent of all reported fish-consumption advisories.2 The geographic extent of mercury advisories covers more than 10 million acres of lakes and more than 400,000 stream miles.3
The fact sheet Mercury Contamination of Aquatic Ecosystems answers many of the basic questions about mercury. For a deeper dive into the topic, download the USGS Circular 1395, highlighted below.
HIGHLIGHTED PUBLICATION: Mercury in the Nation's Streams—Levels, Trends, and Implications FACTS ABOUT MERCURY
- Highly toxic to the nervous system
- Persistent in the environment
- Bioaccumulates (higher concentrations in tissues of aquatic plants and animals than in water)
- Biomagnifies (higher concentrations at increasingly higher levels in the food chain)
- Numerous chemical forms in air, water, sediment, and biota
UNDERSTANDING THE MERCURY CYCLE
Mercury contamination is global and affects many waters that have no obvious mercury source. This is because mercury emissions generally disperse widely in the atmosphere before being deposited to the earth's surface. Mercury is emitted by natural sources, such as volcanoes, geothermal springs, geologic deposits, and the ocean. Human-related sources primarily include coal combustion, waste incineration, industrial uses, and mining. During the last 150 years, human activities have more than doubled natural amounts of mercury in the atmosphere.4
In natural waters, inorganic mercury is generally not a health concern. The real issue is methylmercury, an organic form that is highly toxic to the nervous system. Methylmercury is produced from inorganic mercury by methylation, a microbial process that is controlled by certain bacteria and enhanced by chemical and environmental variables, such as the presence of organic matter and the absence of oxygen. More than 95 percent of all mercury in fish is methylmercury, and this form of mercury biomagnifies to high concentrations at the top of food chains.5
RELATED USGS RESEARCH
- Mercury in the Environment
- USGS Mercury Research Laboratory
- Mercury in Aquatic Ecosystems
- Mercury Statistics and Information
ADDITIONAL RESOURCES
U.S. Environmental Protection Agency
- Science
Use the links below to access web pages describing additional USGS research on mercury and associated topics
Metals and Other Trace Elements
Metals, metalloids, and radionuclides all are trace elements that occur naturally in the Earth's crust. In small quantities many trace elements are essential for health in all living organisms, but some trace elements can be toxic or cause cancer, and some can bioaccumulate. The USGS investigates where and how trace elements make their way into our Nation's surface water and groundwater.Water-Quality Trends From Lake Cores
Sediment cores let us look back in time at the contaminant history of a watershed. Learn about what lake and reservoir sediment cores tell us about trends in metals, organochlorine pesticides, polycyclic aromatic hydrocarbons, and other sediment-related contaminants.Sediment-Associated Contaminants
Stream, river, and lake bed sediment are reservoirs for many contaminants. These contaminants include some “legacy” contaminants, like DDT, PCBs, and chlordane, and chemicals currently in use, like the insecticide bifenthrin and many flame retardants. Learn about techniques used to study sediment-associated contaminants and their importance to aquatic biota.Stream Ecology
Who lives in your stream? Rivers and streams, even small ones, are teeming with a vast number of species, including fish, aquatic invertebrates, and algae. Stream ecology is the study of those aquatic species, the way they interrelate, and their interactions with all aspects of these flowing water systems.Mercury Cycling and Effects on Ecological Communities
Mercury contamination is a serious issue that impacts both ecosystem and human health on a global scale. In its organic (methylmercury) form, mercury is highly bioaccumulative and is among the most toxic compounds commonly found in the environment. Mercury is a relatively distinctive contaminant in the sense that the risk of deleterious environmental effects is more strongly related to ecological...Habitat and Land-Use Influences on Contaminant Bioaccumulation
The distribution and occurrence of contaminants and the associated biological exposure in ecological systems are driven by complex interactions between contaminant sources and mobilization pathways that are overlaid upon the habitat requirements of at-risk organisms. Moreover, landscape structure and land uses can strongly influence the driving processes of contaminant cycling, as well as the...Contaminant Bioaccumulation through Food Webs
This is a broad theme representing the largest component of the Contaminant Ecology Research Program, acting as a bridge between the “Habitat and Land Use Influences” and “Ecological Effects” themes. “Contaminant Bioaccumulation” focuses on quantifying the transfer or movement of contaminants through food webs, and identifying the primary landscape factors and ecological mechanisms that are... - Multimedia
- Publications
Access USGS reports and publications on mercury and water quality. For more publications on mercury, search the USGS Publications Warehouse. Look here for help using the Pubs Warehouse.
Mercury contamination of aquatic ecosystems
Mercury has been well known as an environmental pollutant for several decades. As early as the 1950's it was established that emissions of mercury to the environment could have serious effects on human health. These early studies demonstrated that fish and other wildlife from various ecosystems commonly attain mercury levels of toxicological concern when directly affected by mercury-containing emiAuthorsDavid P. Krabbenhoft, David A. RickertFilter Total Items: 23Chemical and physical controls on mercury source signatures in stream fish from the northeastern United States
Streams in the northeastern U.S. receive mercury (Hg) in varying proportions from atmospheric deposition and legacy point sources, making it difficult to attribute shifts in fish concentrations directly back to changes in Hg source management. Mercury stable isotope tracers were utilized to relate sources of Hg to co-located fish and bed sediments from 23 streams across a forested to urban-industrAuthorsSarah E. Janssen, Karen Riva-Murray, John F. DeWild, Jacob M. Ogorek, Michael T. Tate, Peter C. Van Metre, David P. Krabbenhoft, James F. ColesTopics in coal geochemistry—Short course
This short course was prepared at the request of Servicio Geológico Colombiano (SGC) as a module for staff training. Prior to the short course, the SGC expressed interest in receiving training in (1) geochemistry and quality of coal; (2) geochemistry of trace elements in coal; (3) mercury and halogens in coal; (4) characterization and cycling of atmospheric mercury; (5) mercury, trace elements, anAuthorsAllan KolkerExternal quality assurance project report for the National Atmospheric Deposition Program’s National Trends Network and Mercury Deposition Network, 2015–16
The U.S. Geological Survey Precipitation Chemistry Quality Assurance project operated five distinct programs to provide external quality assurance monitoring for the National Atmospheric Deposition Program’s (NADP) National Trends Network and Mercury Deposition Network during 2015–16. The National Trends Network programs include (1) a field audit program to evaluate sample contamination and stabilAuthorsGregory A. Wetherbee, RoseAnn MartinSpatial patterns and temporal changes in atmospheric-mercury deposition for the midwestern USA, 2001–2016
Spatial patterns and temporal changes in atmospheric-mercury (Hg) deposition were examined in a five-state study area in the Midwestern USA where 32% of the stationary sources of anthropogenic Hg emissions in the continental USA were located. An extensive monitoring record for wet and dry Hg deposition was compiled for 2001–2016, including 4666 weekly precipitation samples at 13 sites and 27 annuaAuthorsMartin R. Risch, Donna M. KenskiLake levels and water quality in comparison to fish mercury body burdens, Voyageurs National Park, Minnesota, 2013–15
Within Voyageurs National Park in Minnesota, lake levels are controlled by a series of dams to support a variety of uses. Previous research indicates a link between these artificially maintained water levels, referred to as rule curves, and mercury concentrations in fish owing to the drying and rewetting of wetlands and other nearshore areas, which may release methylmercury into the water when inuAuthorsVictoria G. Christensen, James H. Larson, Ryan P. Maki, Mark B. Sandheinrich, Mark E. Brigham, Claire Kissane, Jamie F. LeDucOptimizing fish sampling for fish - mercury bioaccumulation factors
Fish Bioaccumulation Factors (BAFs; ratios of mercury (Hg) in fish (Hgfish) and water (Hgwater)) are used to develop Total Maximum Daily Load and water quality criteria for Hg-impaired waters. Both applications require representative Hgfish estimates and, thus, are sensitive to sampling and data-treatment methods. Data collected by fixed protocol from 11 streams in 5 states distributed across theAuthorsBarbara C. Scudder Eikenberry, Karen Riva-Murray, Christopher D. Knightes, Celeste A. Journey, Lia C. Chasar, Mark E. Brigham, Paul M. BradleyEffects of urbanization on mercury deposition and accumulation in New England
We compare total mercury (HgT) loading and methylmercury (MeHg) accumulation in streams and lakes from an urbanized area (Boston, Massachusetts) to rural regions of southern New Hampshire and Maine. The maximum HgT loading, as indicated by HgT atmospheric deposition, HgT emissions, and sediment HgT concentrations, did not coincide with maximum MeHg concentrations in fish. Urbanized ecosystems wereAuthorsAnn T. Chalmers, David P. Krabbenhoft, Peter C. Van Metre, Mark A. NillesMercury in the nation's streams - Levels, trends, and implications
Mercury is a potent neurotoxin that accumulates in fish to levels of concern for human health and the health of fish-eating wildlife. Mercury contamination of fish is the primary reason for issuing fish consumption advisories, which exist in every State in the Nation. Much of the mercury originates from combustion of coal and can travel long distances in the atmosphere before being deposited. ThisAuthorsDennis A. Wentz, Mark E. Brigham, Lia C. Chasar, Michelle A. Lutz, David P. KrabbenhoftAn empirical approach to modeling methylmercury concentrations in an Adirondack stream watershed
Inverse empirical models can inform and improve more complex process-based models by quantifying the principal factors that control water quality variation. Here we developed a multiple regression model that explains 81% of the variation in filtered methylmercury (FMeHg) concentrations in Fishing Brook, a fourth-order stream in the Adirondack Mountains, New York, a known “hot spot” of Hg bioaccumuAuthorsDouglas A. Burns, Elizabeth A. Nystrom, David M. Wolock, Paul M. Bradley, Karen Riva-MurrayMercury bioaccumulation in estuarine wetland fishes: Evaluating habitats and risk to coastal wildlife
Estuaries are globally important areas for methylmercury bioaccumulation because of high methylmercury production rates and use by fish and wildlife. We measured total mercury (THg) concentrations in ten fish species from 32 wetland and open bay sites in San Francisco Bay Estuary (2005–2008). Fish THg concentrations (μg/g dry weight ± standard error) differed by up to 7.4× among estuary habitats.AuthorsCollin A. Eagles-Smith, Joshua T. AckermanMethylmercury-induced changes in gene transcription associated with neuroendocrine disruption in largemouth bass (Micropterus salmoides)
Methyl-mercury (MeHg) is a potent neuroendocrine disruptor that impairs reproductive processes in fish. The objectives of this study were to (1) characterize transcriptomic changes induced by MeHg exposure in the female largemouth bass (LMB) hypothalamus under controlled laboratory conditions, (2) investigate the health and reproductive impacts of MeHg exposure on male and female largemouth bass (AuthorsCatherine A. Richter, Christopher J. Martyniuk, Mandy L. Annis, William G. Brumbaugh, Lia C. Chasar, Nancy D. Denslow, Donald E. TillittMercury in the soil of two contrasting watersheds in the eastern United States
Soil represents the largest store of mercury (Hg) in terrestrial ecosystems, and further study of the factors associated with soil Hg storage is needed to address concerns about the magnitude and persistence of global environmental Hg bioaccumulation. To address this need, we compared total Hg and methyl Hg concentrations and stores in the soil of different landscapes in two watersheds in differenAuthorsDouglas A. Burns, Laurel G. Woodruff, Paul M. Bradley, William F. Cannon - News
Use the links below to find news stories on USGS research on mercury and water quality.
Isotopic tracers in fish in Northeast provide clue to mercury sources
Isotopes of mercury in fish can indicate the source of that mercury, reports a new study from the USGS Regional Stream Quality Assessment.