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
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.
Sources/Usage: Public Domain.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
- 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.