Groundwater pollution occurs as a result of the release of pollutants into the ground into natural underground water reservoirs known as aquifers. Once the pollutants released find their way into groundwater, they cause contamination. It is a type of water pollution that is mainly caused by the release of substances either intentionally or accidentally through anthropogenic activities or natural causes.
The pollutants usually move within aquifers depending on biological, physical, and chemical properties. Processes such as diffusion, dispersion, adsorption, and the speed of moving water often facilitate the movement. But in general, the movement of the contaminants within an aquifer is usually slow and, as such, their concentration tends to be high and in a form called a plume.
As the plume spreads, it might connect with springs and ground wells, making them unsafe for human consumption. Hence, this article discusses the causes, effects, and various solutions to underground water pollution.
Causes of Groundwater Pollution
1. Natural Sources
Naturally occurring substances found in the soil and rocks can be dissolved in water, causing contamination. These substances are sulfates, iron, radionuclides, fluorides, manganese, chlorides, and arsenic. Others, such as the decaying materials in the soil, may seep into underground water and move with it as particles.
Reports by WHO indicate that the most common pollutants are fluoride and arsenic. The natural causes of pollution can be tested using the Groundwater Assessment Platform (GAP). GAP estimates contamination levels using environmental, geological, and topographical data.
2. Septic Systems
Across the world, septic systems are the main cause of pollution of underground water. The pollutants are outflow from privies, septic tanks, and cesspools. 25% of households in the USA, for instance, heavily depend on septic systems to dispose of their waste. This huge number of users relying on the system makes it one of the main pollutants.
Additionally, improperly designed and leaking septic systems release contaminants such as nitrates, oils, bacteria, chemicals, detergents, and viruses into underground water.
Commercial septic tanks pose an even bigger threat because they release organic chemicals such as trichloroethane. Laws in most countries require the septic tank to be constructed far from the water sources to prevent contamination but at times this is not usually the case.
3. Hazardous Waste Disposal
Hazardous wastes such as photographic chemicals, motor oil, cooking oil, paint thinners, medicines, swimming pool chemicals, paints, and garden chemicals should not be disposed of into septic tanks or directly into the environment as they cause serious contamination. These chemicals should be disposed of with the help of a licensed hazardous waste handler.
4. Petroleum Products
Petroleum storage tanks are either located underground or above ground. Also, the transportation of petroleum products is mainly done underground using pipelines. Leakages from these substances can lead to contamination of water.
In the USA, it is estimated that 16,000 chemical spills each year are from trucks, storage containers, and train spillages, especially when transferring oil. The chemicals spilled become diluted with water and seep into the ground where they may cause groundwater contamination.
5. Solid Waste
The Palmer Developmental Group estimated that in developing countries, approximately 0.3 to 0.6 kg/person/day of waste is released into the ground. On the other hand, in developed countries, 0.7 to 1.8 kg/person/day is released. The chemicals from these substances are leached into the groundwater through precipitation and surface runoff.
The waste can also be collected and taken to landfills. If the landfills lack a clay liner and leachate, the chemicals from the wastes will leach and pose a threat to the groundwater.
6. Surface impoundments
These are shallow lagoons used to store liquid waste. The USA, for example, has over 180,000 surface impoundments which can pose a threat to groundwater. Therefore, the impoundments are required to have clay liners or leachates to prevent leaching. In some cases, the leachates may be defective and leakages may occur, leading to contamination of water.
7. Agricultural Chemicals
Millions of tons of agricultural chemicals such as fertilizers and pesticides are used worldwide to increase crop production. Other institutions, such as the Golf Courses, also use these chemicals.
Excessive use of these chemicals can lead to contamination of groundwater. Chemicals such as pesticides are known to remain in the ground for years, and when diluted with the rainwater they seep deeper into the groundwater.
8. Injection wells
They have various uses, ranging from collection of stormwater to disposal of industrial and commercial effluents. When not properly regulated, hazardous chemicals can be disposed of in injection wells. For this reason, if they are not properly located, regulated, and designed; they can cause contamination of groundwater.
9. Other causes
Other causes of ground pollution are abandoned wells, which can act as a pathway for contaminants to reach the aquifers. Also, poorly constructed wells that may lack proper casing and covers may cause groundwater contamination when pollutants find their way into such wells.
Another cause of pollution is mining activities, where, through precipitation, the soluble minerals can be leached from the sites into the groundwater.
Effects of Groundwater Pollution
1. Health Issues
Contaminated groundwater has detrimental effects on human health. In areas where septic tank installation is not set up correctly, human waste may contaminate the water source. The waste may contain hepatitis-causing bacteria that may lead to irreversible damage to the liver.
Also, it may cause dysentery, which leads to severe diarrhea, dehydration, and, in some cases, death. Additional health problems include poisoning that may be a result of the use of excessive pesticides and fertilizers or natural chemicals. The chemicals leach into water sources and poison them. Drinking water from such a source may lead to serious health effects.
2. Affects economic growth
Contamination of groundwater sources renders the area incapable of sustaining plant, human, and animal life. The population in the area reduces and the land value depreciates. Another effect is that it leads to less stability in industries relying on groundwater to produce their goods.
Therefore, the industries in the affected areas will have to outsource water from other regions, which may turn out to be expensive. In addition, they may be forced to close down due to the poor quality of water.
3. Can lead to damaging impacts on the environment such as aquatic systems and the overall ecosystem
Groundwater pollution can lead to devastating environmental changes. One such alteration is the loss of certain nutrients that are essential for the self-sustenance of the ecosystem. Also, when the pollutants mix with water bodies, alteration of the aquatic ecosystem may also occur. Aquatic animals such as fish may die off quickly as a result of too many contaminants in the bodies of water.
Animals and plants using contaminated water may also be affected. Toxic substances accumulate with time in the aquifers and once the prime spreads, it may render the groundwater unsuitable for human and animal consumption. The effects are serious, especially for people who rely on groundwater during drought periods.
Solutions of Groundwater Pollution
1. Legislation
There are federal laws in most countries that help protect the quality of groundwater. Safe Drinking and Clean Water regulations should ensure the protection of drinking water by establishing measures for it to meet health standards.
2. The use of water cleaning systems
Point-of-use treatment systems should be installed in outlets that dispense water for human consumption. The techniques used include chemical disinfection, boiling, solar distillation, filtration, ozone water disinfection, activated charcoal absorption, and ultraviolet disinfection.
Arsenic Removal Filters (ARFs) are usually installed to remove arsenic compounds present. Maintaining these filters is essential to ensure that the drinking water is always safe.
Groundwater Remediation is also another management technique. The biological treatment techniques employed are bioaugmentation, bioslurping, bioventing, phytoremediation, and biosparging. Chemical techniques such as ion exchange, ozone gas injection, membrane separation, and chemical precipitation can also be used.
3. Proper management of the sources of pollution
The landfills should be designed with proper clay and leachate. The maintenance should be done regularly. The location of the landfill should also be far from groundwater areas. Further, any hazardous waste should not be dumped in the landfill unless it is designed for that purpose.
In constructing and managing underground storage tanks, it is important to comply with the set regulations and policies to avoid contamination or even lawsuits. A containment device that acts as a leak back-up should be put in place and any unused underground tanks should be removed.
Underground pipeline installation should be designed professionally. Inspections should be done regularly and any causes of corrosion or leakage noted should be resolved immediately.
4. Recycling
Most landfills in various countries have a recycling plant nearby. Therefore, used petroleum products should be taken to such places. Apart from oil, other recyclable materials such as plastic, bottles, and paper waste can also be taken to recycling plants. The state should provide designated recycling pick-up areas in places that they are not yet established.
Together with other environmental organizations, the state can mobilize people to participate in the recycling initiative. They can do this by holding awareness campaigns and educating communities on the importance of recycling.
What is groundwater pollution?
Groundwater is one of the sources of clean water that humans use. This source is being polluted once man-made products such as oil, gasoline, road salt, and other chemicals are mixed with it. If the groundwater is already polluted by such products, it is no longer fit to be consumed by humans and animals as it is already unsafe and contaminated.
Other than those products, groundwater pollution also occurs when the chemicals from the land’s surface move down to the groundwater through the soil. An example of this is when liquid industrial waste is poured onto the land and find its way into the groundwater supplies.
Another example is when farmers use pesticides and fertilizers, some of the chemicals move from the soil into the groundwater supply. Furthermore, toxic substances from mining sites, underground storage tanks, and septic tanks can also cause groundwater pollution once the landfills are leaky, which could lead to groundwater contamination.
How can soil pollution lead to underground water pollution?
Soil pollution usually leads to underground water pollution as the chemicals that are destroying the soil are moving down to the groundwater supplies. The chemicals that are being poured or inhaled by the soil are causing the soil pollution.
As time passes by, the toxic substances continues to move from the soil surface and go deeper until they reach the groundwater. Once the groundwater is reached, groundwater pollution will be caused, which could lead to groundwater contamination.
For example, large industrial plants dump their chemical waste on top of the soil, assuming that it will not pollute the soil. Once they do such action, the chemicals will be absorbed by the soil, destroying its habitable properties for plants and underground animals.
As the chemicals continue to travel from the soil surface, they will eventually reach the groundwater, causing groundwater pollution and contamination.
Another example of this is in agriculture. As the pesticides, fertilizers, and animal waste are mixed and spread out on land, pollutants such as nitrates and bacteria may be developed and continue to seep through the soil. These pollutants will continue to move down until they reach the groundwater supplies.
The pollution and contamination of the groundwater could cause serious adverse effects on plants, animals, and humans who are using the contaminated groundwater as their main supply of the said basic needs.
Furthermore, the soil pollution from untreated waste tanks, landfills, and mining and quarrying sites could also cause groundwater pollution through the same process as the others.
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