Meghan Hodges
Groundwater pollution, also known as groundwater contamination, is a global issue that occurs when pollutants are released into the ground and make their way into underground water sources, known as aquifers. These pollutants can come from various sources, including human activities such as agriculture, mining, and quarrying, as well as natural sources like arsenic and iron found in rocks and soils. In this topic, we will explore the major sources of pollution that are stored underground and the impact they have on our environment and water resources.
| Characteristics | Values | |
|---|---|---|
| Groundwater pollution causes | Natural: Presence of arsenic, iron, chlorides, sulfates, fluoride, radionuclides, decaying organic matter; Sea level rise; Flood mitigation schemes; Prolonged depletion of groundwater; Draining of acid sulfate soils | |
| Anthropogenic | Mining and quarrying; Landfills; Leachate from sanitary landfills; Chemicals from precipitation and runoff; Hydraulic fracturing; On-site sanitation systems; Effluent from wastewater treatment plants; Leaking sewers; Petrol filling stations; Overuse of fertilizers in agriculture; Slurry, pesticides, fungicides, insecticides, herbicides, and animal waste | |
| Extent of groundwater pollution | A study of US groundwater quality between 1991 and 2004 showed that 23% of domestic wells had contaminants above human-health benchmarks. | |
| Impact of groundwater pollution | In Tanzania, consumption of water from shallow wells has resulted in large numbers of people suffering from water-borne diseases. | |
| Action taken | Treatment or remediation of the polluted groundwater; Abandoning the use of the aquifer's groundwater and finding an alternative source of water |
Explore related products
What You'll Learn
Mining and quarrying
Water pollution is a common issue associated with mining and quarrying activities. Water is used in various processes, such as mineral processing, dust suppression, and slurry transport, and it can become polluted by carrying contaminants when disposed of. Acid mine drainage (AMD), for example, contributes to the solubility of toxic metals that can eventually enter groundwater systems. Additionally, cyanide is often used in the leaching process to extract desired metals, posing significant environmental risks. Placer mining, which involves using bulldozers, dredges, or hydraulic jets to extract ore from stream beds or flood plains, is particularly notorious for causing water pollution.
The impact of mining and quarrying on groundwater pollution is significant. In addition to the contamination of groundwater with toxic metals and chemicals, these activities can affect the water table, springs, and underground wells. Sand mining, for instance, has resulted in increased water turbidity in the majority of offshore areas of Lake Hongze in China.
While mining and quarrying can have adverse environmental consequences, it is worth noting that the industry is moving towards more sustainable practices. Underground mining, phytomining, and asteroid mining are examples of techniques that aim to reduce ecological scarring and land usage. Additionally, strict international regulations have helped reduce pollution from mining operations, although challenges remain in developing countries where illegal small-scale operations, known as "artisanal mining," persist.
World's Most Polluted Rivers: A Troubling Overview
You may want to see also
Explore related products
Agricultural pollution
Another source of agricultural pollution is the inappropriate disposal of waste, including septic sludge (untreated fecal matter), wastewater sludge, and biosolids. Biosolids, in particular, are produced as a soil amendment for agriculture and can be contaminated with trace elements, microplastics, and persistent organic pollutants (POPs). These contaminants can pollute agricultural soils and pose risks to human health.
Irrigation with treated wastewater is also a common practice in some regions facing water shortages, such as China, Mexico, and countries in the Near East and North Africa. While treated wastewater has a lower contaminant and microplastics content, the use of water in agriculture can still lead to groundwater pollution. This is especially concerning with the use of firefighting foams containing perfluoralkyl substances (PFAS), which are now listed as POPs.
Excessive fertilization is another form of agricultural pollution, where nitrogen fertilizer not absorbed by crops can convert into nitrates, contaminating neighbouring water bodies and drinking water sources. This contributes to the eutrophication of surface water bodies and terrestrial ecosystems, leading to adverse health effects such as various cancers, thyroid disease, and neural tube defects. Ammonia particle emissions from agriculture can also have significant health side effects when inhaled.
Soil pollution, caused by agricultural practices, is a growing threat to human health. It can be polluted by heavy metals, organic chemicals, pesticides, biological pathogens, and micro/nanoplastic particles. This reduces soil fertility, leads to food crop contamination, and causes water pollution when pollutants wash into rivers. Additionally, cultivation for agricultural production can release soil into the atmosphere as dust, causing respiratory issues and increasing the risk of pulmonary diseases.
Niagara Falls: Polluted Paradise?
You may want to see also
Explore related products
Landfills
The organic mass in landfills releases methane gas as it decomposes. Methane is a potent greenhouse gas, 84 times more effective than carbon dioxide at absorbing the sun's heat, and significantly contributes to climate change. Air pollutants escaping from landfills can also cause respiratory problems in nearby residents.
Leachate from landfills can contaminate nearby water sources, damaging ecosystems. While new landfills are required to be lined with clay or synthetic materials to protect surrounding groundwater, older landfills may lack these measures and are often close to surface waters and in permeable soils. Leachate can contain high levels of ammonia, which can cause eutrophication (a lack of oxygen due to increased plant growth) in nearby water sources, creating "dead zones" where animals cannot survive. In addition to ammonia, leachate contains toxins such as mercury due to the presence of hazardous materials in landfills.
Health impacts associated with landfills include the spread of waterborne diseases like typhoid and cholera, as well as non-communicable diseases like cancer and asthma. Studies have also shown an increased risk of congenital malformations in children born to families living near hazardous waste landfill sites.
Soil Pollution: Understanding the Contamination Process
You may want to see also
Explore related products
Hydraulic fracturing
Water pollution is a significant concern with hydraulic fracturing. The large volume of water used in each well—between 1.5 million and 9.7 million gallons per well in the US—not only strains local water resources but also poses a risk of contamination. The water used in fracking is typically freshwater drawn from groundwater and surface water sources. This water becomes contaminated with chemicals during the extraction process, and only 15-35% of it is recovered, leaving the rest in the ground, where it can potentially contaminate groundwater. The chemicals used in fracking have been detected in drinking water sources near extraction sites, and improper well installation, chemical spills, and ineffective containment of flowback (water flowing out of the well) can also lead to water contamination.
Air pollution is another issue associated with hydraulic fracturing. The process releases toxic air contaminants such as benzene, toluene, ethylbenzene, xylene, fine particulate matter (PM2.5), hydrogen sulfide, silica dust, nitrogen oxides, and volatile organic compounds. These compounds contribute to smog formation and have been linked to various health issues, including respiratory, neurological, and cardiovascular problems. The combustion processes involved in fracking, such as flaring off excess natural gas, also release toxic chemicals into the air.
While some studies suggest that the risk of hydraulic fracturing fluids contaminating shallow groundwater is low, the potential for systematic stray gas contamination exists. Accidental spillage of hydraulic fracturing fluid and produced water is considered a significant source of groundwater contamination. The integrity of the shale oil/gas well structure and its geological location play a crucial role in mitigating these risks.
The environmental and health impacts of hydraulic fracturing are complex and not yet fully understood. The specific chemicals used in the process are often not disclosed, making it challenging to assess the full scope of the risks. As research into the safety of fracking continues, it is essential to balance the benefits of this method for energy extraction with the potential dangers it poses to human health and the environment.
Acetic Acid: Friend or Foe?
You may want to see also
Explore related products
Natural causes
While groundwater contamination is often a result of human activity, there are several natural causes as well. Groundwater is the water present beneath the Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30% of all readily available freshwater in the world is groundwater.
One of the natural causes of groundwater pollution is saltwater intrusion. This occurs when seawater intrudes into freshwater aquifers, rendering the water unusable. This is often intensified by human activities such as over-abstraction of groundwater, which can also lead to land subsidence and infrastructure damage. Saline ingress following over-drafting of aquifers is another example of natural groundwater pollution.
Another natural source of groundwater pollution is the leaching of minerals like arsenic, iron, chlorides, sulfates, fluoride, radionuclides, and aluminium. This can occur due to geological disturbances or the dissolution of organic matter in the aquifer sediments, which creates anaerobic conditions that release arsenic into the water. The use of toxins such as lead and arsenic in 19th-century mining activities has also led to the persistence of these pollutants in today's abandoned mine shafts.
Natural gas drilling, or "fracking," is another potential source of groundwater pollution. While the impact of fracking fluids on shallow groundwater is debated, researchers have hypothesized that the potential for systematic stray gas contamination depends on the integrity of the shale oil/gas well structure and its relative geological location to local fracture systems.
Agricultural activities can also contribute to groundwater pollution through the use of pesticides, fertilizers, slurry, fungicides, insecticides, herbicides, and animal waste. These substances can seep into underground water sources and contaminate them. The heavy use of nitrogenous fertilizers in cropping systems is the largest contributor to anthropogenic nitrogen in groundwater worldwide.
Groundwater pollution can also occur due to natural processes such as underground gasification and the leaching of underground residue by natural groundwater flow after gasification. Inorganic pollutants are primarily derived from ash leachate, while organic pollutants and ammonia are derived from condensed vapors.
Packaging Waste: A Growing Pollution Problem
You may want to see also
Frequently asked questions
Groundwater pollution, also known as groundwater contamination, occurs when pollutants are released into the ground and make their way into groundwater.
Groundwater pollution can be caused by both natural and human factors. Natural sources of groundwater pollution include arsenic, iron, chlorides, sulfates, fluoride, and radionuclides found in rocks and soils, as well as decaying organic matter. Human activities such as mining and quarrying, agriculture, and improper waste disposal in landfills also contribute significantly to groundwater pollution.
Mining and quarrying activities can release pollutants that were previously trapped in rocks into nearby underground water sources. These pollutants may include toxic chemicals such as lead, arsenic, acid, iron, sulfates, and aluminum.
Agriculture is a major source of groundwater pollution due to the use of fertilizers, pesticides, and animal waste. When it rains, these substances are washed into waterways, contaminating groundwater sources. Additionally, the spreading of slurry, fungicides, insecticides, herbicides, and animal waste on land can result in pollutants such as nitrates and bacteria seeping into underground water sources.
Landfills are designated areas for garbage disposal, and they are supposed to have a protective bottom layer to prevent contaminants from leaching into groundwater. However, older landfills may lack this protective layer, and even closed landfills can pose a threat if they are not properly capped with an impermeable material before closure. Leachate from sanitary landfills can contaminate groundwater with chemicals, waste, and other pollutants.
