What is Groundwater Pollution?
Groundwater pollution occurs as a result of release of pollutants into the ground to 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 release of substances either intentionally or accidentally through anthropogenic activities or natural causes.
The pollutants usually move within an aquifers depending on biological, physical, and chemical properties. Processes such as diffusion, dispersion, adsorption, and the speed of moving water often facilitates 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 solutions to underground water pollution.
Causes of Groundwater Pollution
1. Natural Sources
Naturally occurring substances found in the soils and rocks can be dissolved in water causing contamination. This substances are sulfates, iron, radionuclides, fluorides, manganese, chlorides and arsenic. Others such as the decaying materials in the soil may seep in underground water and move with it as particles.
Reports by WHO indicate that the most common pollutants are fluoride and arsenic. Natural cause of pollution can be tested using the Groundwater Assessment Platform (GAP). GAP estimates contamination levels using environmental, geological and the topographical data.
2. Septic Systems
Across the world, septic systems are the main cause of pollution of underground water. The pollutants are out flow from privies, septic tanks and the cesspools. 25% of household in the USA, for instance, heavily depend on the 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 even a much 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 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 pipeline. Leakages from this substances can lead to contamination of water. In 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 and may cause groundwater contamination.
5. Solid Waste
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 hand, in developed countries 0.7 to 1.8 kg/person/day is released. The chemicals from this substances are leached into the ground water through precipitation and surface run off.
The wastes 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 wastes. The USA, for example, has over 180,000 surface impoundments which can pose a threat to ground water. Therefore, the impoundments are required to have clay liners or leachates to prevent the 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 rain water they seep deeper into the groundwater.
8. Injection wells
They have various uses ranging from collection or storm water to disposal of industrial and commercial effluents. When not properly regulated, hazardous chemicals can be disposed of from injection wells. For this reason, if not properly located, regulated, and designed; they can cause contamination of ground water.
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 ground water contamination that is 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 to the ground water.
Effects of Groundwater Pollution
1. Health Issues
Contaminated ground water have detrimental effects on health. In areas where septic tanks installation is not set up correctly, the 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 as a result of use of excessive pesticides and fertilizers or natural chemicals. The chemicals leach into water sources and poison them. Drinking of water from such a source may lead to serious health effects.
2. Affects economic growth
Contamination of ground water 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 ground water to produce their goods.
Therefore, the industries in affected areas will have to outsource for 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 loss of certain nutrients that are essential for 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 fishes may die off quickly as a result of too much contaminants in the water bodies.
Animals and plants using the contaminated water may also be affected. Toxic substances accumulate with time in the aquifers and once the prime spreads it may render the ground water unsuitable for human and animal consumption. The effects are serious especially in people who rely on groundwater during drought periods.
Solutions of Groundwater Pollution
1. Legislation
There are federal laws in most countries that help in protecting the quality of ground water. Safe Drinking and Clean Water regulations should ensure protection of drinking water by establishing measures for them to meet the 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 disinfections. Arsenic Removal Filters (ARFs) are usually installed to remove arsenic compounds present. Maintenance of this filters is essential to ensure that the drinking water is always safe.
Ground water Remediation is also another management technique. The biological treatment techniques employed are bioaugmentation, bioslurping, bioventing, phytoremediation and biosparging. Chemicals 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 leachates. The maintenance should be done regularly. The location of the landfill should also be far from groundwater areas. Further, any hazardous wastes 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 law suits. A containment device that acts as a leak back up should be put in place and any unused underground tanks should be removed. Underground pipelines installation should be designed professionally. Inspections should be done regularly and causes of corrosion or leakages 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, bottle and paper wastes can also be taken to recycling plants. The state should provide designated recycling pick up areas in places that they are not established.
Together with other environmental organizations, the state can mobilize people to participate in the recycling initiative. They can do this through holding awareness campaigns and educating communities of the importance of recycling.
