As settlers traveled west and mined the American landscape, thousands of new mines were created over the centuries and then abandoned. Now, these long forgotten remnants of a bygone area still haunt us, as their operations left behind materials and rock exposures that can be easily eroded and carried downstream. The USGS helps track the sources of acidic mine drainage and helps land managers develop better mitigation strategies.
BACKGROUND
Mine drainage refers to any surface water or groundwater that drains from an active or abandoned mining operation. Mine drainage can be high-quality similar to natural waters or contaminated by leftover materials. Polluted mine drainage can be extremely acidic and is often laden with high concentrations of toxic, heavy metals. In general, the more acidic the water, the more likely it is to be harmful to living organisms.
Mine drainage forms from a chemical reaction between water and rocks containing sulfur-bearing minerals. The resulting waters become rich in sulfuric acid and dissolved iron. As the iron settles out of the water, it can form red, orange, or yellow sediments in the bottom of streams. The acidic runoff further dissolves heavy metals such as copper, lead, mercury into groundwater or surface water. The rate and degree by which acid-mine drainage proceeds can be increased by the action of certain bacteria.
THE CHEMISTRY OF MINE DRAINAGE
Because the chemistry of water samples can rapidly change if removed from the mine, many mine drainage measurements are made in the field. The first measurement typically looks at acidity, which is reported as pH. Aneutral pH has a value of 7. Any sample that reads below a pH of 7 is characterized as beingacidic. Anything greater than 7 is described as beingbasic. The more acidic the water is, the better it is at eroding mining slag, rocks, and other materials. The water then transports the contaminated mine materials to nearby rivers before eventually depositing the materials downstream. Some mine drainage has been seen to have pH in the 2.5-4 range1.
Another water-quality parameter that is useful for characterizing water quality of acid mine drainage is specific conductance. Conductance is a measurement of the electrical conductivity in a water sample and is a indicator of what's dissolved in a liquid. It is also very inexpensive to measure, unlike testing for metals and other pollutants. Different substances will affect the conductance of water, allowing scientists to use changes in conductance as an indicator of changes of whatever is in the water - in this case the amount of contaminants coming from the mine.
RELATED USGS RESEARCH
- USGS Mine Drainage Activities
- Contamination associated with active and abandoned hard-rock mining
- USGS Central Mineral Resources team
ADDITIONAL RESOURCES
U.S. Environmental Protection Agency
Examples of research USGS conducts on mine drainage.
Emerging Geoenvironmental Issues Related to Proposed Mining in the Lake Superior Region
Emerging Geoenvironmental Issues Related to Proposed Mining in the Lake Superior Region
Gold King Mine release (2015): USGS water-quality data and activities
Gold King Mine release (2015): USGS water-quality data and activities
Chemical Modeling of Acid Waters Questa Baseline and Pre-Mining Ground-Water Quality Investigation, Red River Valley Basin, New Mexico
Chemical Modeling of Acid Waters Questa Baseline and Pre-Mining Ground-Water Quality Investigation, Red River Valley Basin, New Mexico
The USGS produces many types of multimedia products. Use the links below to browse our offerings of photographs, podcasts, other related multimedia related mine drainage.
Listen to hear the answer.
The USGS has a vast library of research on the water people rely on everyday. Here's a few examples of publications that define the current understanding of mine drainage.
Challenges in recovering resources from acid mine drainage Challenges in recovering resources from acid mine drainage
From extreme pH to extreme temperature: An issue in honor of the geochemical contributions of Kirk Nordstrom, USGS hydrogeochemist From extreme pH to extreme temperature: An issue in honor of the geochemical contributions of Kirk Nordstrom, USGS hydrogeochemist
A comparison of pre- and post-remediation water quality, Mineral Creek, Colorado A comparison of pre- and post-remediation water quality, Mineral Creek, Colorado
U.S. Geological Survey Field Leach Test for Assessing Water Reactivity and Leaching Potential of Mine Wastes, Soils, and Other Geologic and Environmental Materials U.S. Geological Survey Field Leach Test for Assessing Water Reactivity and Leaching Potential of Mine Wastes, Soils, and Other Geologic and Environmental Materials
Evaluating remedial alternatives for an acid mine drainage stream: Application of a reactive transport model Evaluating remedial alternatives for an acid mine drainage stream: Application of a reactive transport model
Explore the software scientists use to show what is happening in the waters around us.
PHREEQC Version 3 PHREEQC Version 3
Below are frequently asked questions associated with mine drainage.
How does mine drainage occur? How does mine drainage occur?
Mine drainage is surface water or groundwater that drains from an active or abandoned mine. In some cases, pyrite (an iron sulfide mineral) is exposed and reacts with air and water to form sulfuric acid and dissolved iron. Some or all of this iron can precipitate to form the red, orange, or yellow sediments in the bottom of streams containing mine drainage. The acid runoff further dissolves heavy...
How does mine drainage occur?
Mine drainage is surface water or groundwater that drains from an active or abandoned mine. In some cases, pyrite (an iron sulfide mineral) is exposed and reacts with air and water to form sulfuric acid and dissolved iron. Some or all of this iron can precipitate to form the red, orange, or yellow sediments in the bottom of streams containing mine drainage. The acid runoff further dissolves heavy...
How can I find U.S. Bureau of Mines publications? How can I find U.S. Bureau of Mines publications?
After 85 years of service, the U.S. Bureau of Mines (USBM) closed in 1996. Certain functions, such as the collection, analysis, and dissemination of minerals information, have been returned to the U.S. Geological Survey (USGS). For information on former USBM programs or publications, please see the following sources: Selected U.S. Bureau of Mines (USBM) Publications Historical Files from Federal...
How can I find U.S. Bureau of Mines publications?
After 85 years of service, the U.S. Bureau of Mines (USBM) closed in 1996. Certain functions, such as the collection, analysis, and dissemination of minerals information, have been returned to the U.S. Geological Survey (USGS). For information on former USBM programs or publications, please see the following sources: Selected U.S. Bureau of Mines (USBM) Publications Historical Files from Federal...
As settlers traveled west and mined the American landscape, thousands of new mines were created over the centuries and then abandoned. Now, these long forgotten remnants of a bygone area still haunt us, as their operations left behind materials and rock exposures that can be easily eroded and carried downstream. The USGS helps track the sources of acidic mine drainage and helps land managers develop better mitigation strategies.
BACKGROUND
Mine drainage refers to any surface water or groundwater that drains from an active or abandoned mining operation. Mine drainage can be high-quality similar to natural waters or contaminated by leftover materials. Polluted mine drainage can be extremely acidic and is often laden with high concentrations of toxic, heavy metals. In general, the more acidic the water, the more likely it is to be harmful to living organisms.
Mine drainage forms from a chemical reaction between water and rocks containing sulfur-bearing minerals. The resulting waters become rich in sulfuric acid and dissolved iron. As the iron settles out of the water, it can form red, orange, or yellow sediments in the bottom of streams. The acidic runoff further dissolves heavy metals such as copper, lead, mercury into groundwater or surface water. The rate and degree by which acid-mine drainage proceeds can be increased by the action of certain bacteria.
THE CHEMISTRY OF MINE DRAINAGE
Because the chemistry of water samples can rapidly change if removed from the mine, many mine drainage measurements are made in the field. The first measurement typically looks at acidity, which is reported as pH. Aneutral pH has a value of 7. Any sample that reads below a pH of 7 is characterized as beingacidic. Anything greater than 7 is described as beingbasic. The more acidic the water is, the better it is at eroding mining slag, rocks, and other materials. The water then transports the contaminated mine materials to nearby rivers before eventually depositing the materials downstream. Some mine drainage has been seen to have pH in the 2.5-4 range1.
Another water-quality parameter that is useful for characterizing water quality of acid mine drainage is specific conductance. Conductance is a measurement of the electrical conductivity in a water sample and is a indicator of what's dissolved in a liquid. It is also very inexpensive to measure, unlike testing for metals and other pollutants. Different substances will affect the conductance of water, allowing scientists to use changes in conductance as an indicator of changes of whatever is in the water - in this case the amount of contaminants coming from the mine.
RELATED USGS RESEARCH
- USGS Mine Drainage Activities
- Contamination associated with active and abandoned hard-rock mining
- USGS Central Mineral Resources team
ADDITIONAL RESOURCES
U.S. Environmental Protection Agency
Examples of research USGS conducts on mine drainage.
Emerging Geoenvironmental Issues Related to Proposed Mining in the Lake Superior Region
Emerging Geoenvironmental Issues Related to Proposed Mining in the Lake Superior Region
Gold King Mine release (2015): USGS water-quality data and activities
Gold King Mine release (2015): USGS water-quality data and activities
Chemical Modeling of Acid Waters Questa Baseline and Pre-Mining Ground-Water Quality Investigation, Red River Valley Basin, New Mexico
Chemical Modeling of Acid Waters Questa Baseline and Pre-Mining Ground-Water Quality Investigation, Red River Valley Basin, New Mexico
The USGS produces many types of multimedia products. Use the links below to browse our offerings of photographs, podcasts, other related multimedia related mine drainage.
Listen to hear the answer.
The USGS has a vast library of research on the water people rely on everyday. Here's a few examples of publications that define the current understanding of mine drainage.
Challenges in recovering resources from acid mine drainage Challenges in recovering resources from acid mine drainage
From extreme pH to extreme temperature: An issue in honor of the geochemical contributions of Kirk Nordstrom, USGS hydrogeochemist From extreme pH to extreme temperature: An issue in honor of the geochemical contributions of Kirk Nordstrom, USGS hydrogeochemist
A comparison of pre- and post-remediation water quality, Mineral Creek, Colorado A comparison of pre- and post-remediation water quality, Mineral Creek, Colorado
U.S. Geological Survey Field Leach Test for Assessing Water Reactivity and Leaching Potential of Mine Wastes, Soils, and Other Geologic and Environmental Materials U.S. Geological Survey Field Leach Test for Assessing Water Reactivity and Leaching Potential of Mine Wastes, Soils, and Other Geologic and Environmental Materials
Evaluating remedial alternatives for an acid mine drainage stream: Application of a reactive transport model Evaluating remedial alternatives for an acid mine drainage stream: Application of a reactive transport model
Explore the software scientists use to show what is happening in the waters around us.
PHREEQC Version 3 PHREEQC Version 3
Below are frequently asked questions associated with mine drainage.
How does mine drainage occur? How does mine drainage occur?
Mine drainage is surface water or groundwater that drains from an active or abandoned mine. In some cases, pyrite (an iron sulfide mineral) is exposed and reacts with air and water to form sulfuric acid and dissolved iron. Some or all of this iron can precipitate to form the red, orange, or yellow sediments in the bottom of streams containing mine drainage. The acid runoff further dissolves heavy...
How does mine drainage occur?
Mine drainage is surface water or groundwater that drains from an active or abandoned mine. In some cases, pyrite (an iron sulfide mineral) is exposed and reacts with air and water to form sulfuric acid and dissolved iron. Some or all of this iron can precipitate to form the red, orange, or yellow sediments in the bottom of streams containing mine drainage. The acid runoff further dissolves heavy...
How can I find U.S. Bureau of Mines publications? How can I find U.S. Bureau of Mines publications?
After 85 years of service, the U.S. Bureau of Mines (USBM) closed in 1996. Certain functions, such as the collection, analysis, and dissemination of minerals information, have been returned to the U.S. Geological Survey (USGS). For information on former USBM programs or publications, please see the following sources: Selected U.S. Bureau of Mines (USBM) Publications Historical Files from Federal...
How can I find U.S. Bureau of Mines publications?
After 85 years of service, the U.S. Bureau of Mines (USBM) closed in 1996. Certain functions, such as the collection, analysis, and dissemination of minerals information, have been returned to the U.S. Geological Survey (USGS). For information on former USBM programs or publications, please see the following sources: Selected U.S. Bureau of Mines (USBM) Publications Historical Files from Federal...