Fresh water is a source of life. It is a generally known fact that a human body consists of about seventy percent of water. Thus, water is one of the essential matters that provides vital functions of any living organism on Earth. The amount of freshwater is only about three percent out of the entire quantity of water on the planet, and it reduces every year. Groundwater is the main source of the freshwater.
The rapid growth and development of the various kinds of industries in the modern times increases the level of environmental pollution. Groundwater may contain poisonous substances that affect human health when consumed or deteriorate the environment when the water is thoughtlessly spilled on the surface. The quality of the fresh groundwater might change during its usage as it may be affected by the various activities; however, such changes and impacts might not always be evident immediately and, therefore, negatively affect human health.
Hence, the contamination of fresh groundwater with waste products has become a global problem worldwide. Scientists distinguish several types of groundwater pollution: biological, chemical, radioactive, and thermal. To decrease the level of further pollution of the groundwater, it is very important to know what causes pollution, to be able to define a type of pollution and to know the harmful effect of it on human life. This paper will discuss all types of groundwater pollution and its sources, the effect of groundwater pollution on human life, and some ways of cleaning the groundwater.
Groundwater is water that gets into the soil through cracks or holes on the Earth’s surface. Contamination of the groundwater is a change of physicochemical and biological properties of water that worsen its qualities and make water partly or completely unusable. After this water gets underground, it moves around, dissolving various particles in the soil. This may be one of the main causes of its contamination. Therefore, pollution of the groundwater mostly depends on pollution of the soil.
Groundwater has been always considered much cleaner and safer to use compared to the surface water. It is presumed that soil plays a role of a filter for the groundwater that is going through it. Nevertheless, many outbreaks of the different diseases are caused by the usage of untreated groundwater for different domestic purposes. The level of the groundwater pollution depends on various factors, such as the distance from the source of pollution, certain characteristics of soil, including its structure, texture, the rate of infiltration and ions, depth of the water table, and the rainfall pattern. Contaminating substances can get into the groundwater from the land surface, from the structures under the surface but higher than the water table, from the systems lower than the water table.
Biological Pollution of Groundwater
Biological pollution of the groundwater can be extremely dangerous to human life. It is caused by the different pathogenic microorganisms and bacteria that get into the ground with the waste products. Statistics provided by the World Health Organization show that 2.1 million people die every year from diarrhea; ten percent of the population in the developing countries are affected by infections caused by the various parasitic worms, while about eighty percent of all illnesses in the developing countries can be referred to infections provoked by unclean water and poor sanitation conditions (Ezekwe, Chima, & Nikogori, 2013). This kind of pollution can be caused by the several sources, such as the natural ones, inappropriate treatment of fecal waste, damage, or improperly designed septic system (septic tanks and cesspools), landfills, improperly built and abandoned wells and drainage wells, inappropriately designed irrigation wells, poorly constructed or damaged sewerage system, leakage of sewerage pipes, feces of birds and warm-blooded animals, and the other abattoir wastes.
An inappropriate treatment of fecal waste, poorly constructed or damaged sewerage system, and leakage of sewerage pipes are the main reasons for discharge of fecal coliform bacteria and other pathogenic microorganisms into the groundwater. However, this and some other kinds of bacteria and pathogenic microorganisms can get into the groundwater naturally as well (Ezekwe et al., 2013). This process happens because of slime, which is formed by the naturally present microorganisms in the groundwater (Ezekwe et al., 2013). The slime clings to the surface of any devices that are in touch with water. Disturbance of these devices may cause slime to move and release the bacteria. Insects might carry coliform bacteria to improperly covered, abandoned, or unplugged wells. It gives an opportunity for the bacteria to get to the deeper level of water (Ezekwe et al., 2013).
Some pathogenic organisms, such as those that can be naturally present in groundwater, might be a reason for diseases among individuals with suppressed immune mechanisms. For example, such bacterial agents as Pseudomonas acrogiriossi, species of Acire Bacterias, and Flavobacterium can cause infections of nose, ears, throat, eyes, skin, and mucous membranes of the other organs if one consumes the contaminated water (Ezekwe et al., 2013).
Besides fecal coliform bacteria, viruses, fungus, and other pathogenic organisms may also pollute groundwater. For instance, according to the statistics provided by the Centre for Disease Control, salmonella, and rota and Hepatitis A viruses were found in twenty percent of groundwater around the United States (Ezekwe et al., 2013). Besides, it is proven that different viruses can get through the septic tank systems from the toilet to the nearby groundwater systems in about eighteen hours (Ezekwe et al., 2013). The other reason for the biological pollution of the groundwater is cattle and birds’ excrement. Cattle’s excrement can carry millions of Cryptosporidium, E. coli O157 : H7, Giardia, and other dangerous microorganisms (Ezekwe et al., 2013). Chicken excrement might have such pathogenic bacteria as salmonella and campylobacter (Ezekwe et al., 2013). All these dangerous microorganisms can percolate through the soil with water into the groundwater, especially during the heavy rains.
Even though the majority of coliform bacteria are not dangerous and do not cause diseases, their presence in the water might be an indicator of water pollution by the fecal substances, and the presence of microorganisms that contribute to the boosting of different bacteria and viruses. Among all water carrying diseases, the most dangerous are cholera, typhoid, polio infections, schistosomiasis, hepatitis, and bacterial and amoebic dysentery (Ezekwe et al., 2013). Typical symptoms of the diseases that are caused by the consuming of fecal content are diarrhea, nausea, fever, vomiting, and similar to flu symptoms.
Another major biological source of pollution is meat production wastes, particularly abattoir. The waste products of a slaughterhouse include such materials as fecal matter, rumen, fat, horns, intestinal content, scraps of tissue, blood, and bones. The results of tests provided by Ogunnusi and Dahunsi (2014) show that this kind of waste can pollute groundwater and be very dangerous for the environment and human health. According to their research, the presence of the blood in the abattoir wastewater drastically increases the level of bacteria because of the high quantity of proteins in the blood that is an enabling environment for the growth of microorganisms. The waste water mixed with the stream water may contain the following bacteria: Escherichia coli, Staphylococcus aureus, Pseudomonas sp, and fungi such as Aspergillus niger and Fusarium (Ogunnusi & Dahunsi, 2014). Such a mixture may get to the groundwater and pollute it.
It is important to know that pathogenic microorganisms survive in groundwater much better than in the surface water. This phenomenon can be explained by the presence of the more enabling environment in the groundwater than in the surface one. Firstly, there is no sunlight that kills some pathogenic microorganisms; besides, the temperature is lower, and bacterial antagonism is absent underground. Thus, in this suitable environment, such bacteria as plague bacillus, salmonella, typhoid bacillus, and some others can survive in the wet silt or sand from twenty days to several months. Moreover, some pathogenic microorganisms can live in groundwater for over a year.
Chemical Pollution of Groundwater
The chemical pollution of the groundwater presupposes a change of the natural chemical characteristics of water due to the presence of harmful compounding materials. The main source of the groundwater chemical pollution is liquid and solid waste from the various industrial manufacturing factories. The chemically contaminated water might change its color or smell (Hamill & Bell, 2013). For instance, brown color may signify the presence of peat or other organic substances (Hamill & Bell, 2013). However, groundwater can be chemically contaminated due to the natural reasons too with wastes consisting of different inorganic and organic substances.
The inorganic class of pollution may include such materials as various inorganic acids and their salts combined with other matters, caused by the discharge during the different industrial processes, ammonia that may get into the groundwater from the waste products of food and some other productions. Nitrates and phosphates may get into the groundwater as a consequence of the use of fertilizers in the agricultural industry (Hassanien, 2009). What is more, heavy metals and their various combinations with other matters produced as a result of mining and metal manufacture can also cause groundwater pollution.
Even though the negative results of consumption of chemically polluted water in small doses sometimes are not as quickly evident as those of consumption of biologically polluted water, it still can be extremely dangerous and even fatal to humans. For instance, antimony that may get into the environment by the natural causes or as a waste product of manufacturing batteries, ceramics, flame retardants, and many others can change the levels of glucose and cholesterol in the blood (“Contaminants Found in Groundwater,” n.d.). Arsenic that may pollute the groundwater because of the natural reasons or as a result of smelting lead, copper, zinc ore, or usage of pesticides in agriculture is a carcinogen that may decrease blood hemoglobin and cause kidney and liver damage (“Contaminants Found in Groundwater,” n.d.). Cadmium that may be found in low concentrations in the environment and may get into the groundwater if dissolved by acid waters or as a result of mining, batteries, metal plating, and some other productions, may be a reason for high blood pressure, anemia, liver, and kidney damage (“Contaminants Found in Groundwater,” n.d.). It can destroy red blood cells and testicular tissue, and biochemically replace zinc in the human body (“Contaminants Found in Groundwater,” n.d.).
The old mining operations runoff, fossil-fuel combustion, cement-plant emissions, waste incineration, and mineral leaching might be the reasons for Chromium VI penetration into groundwater. This inorganic substance can cause damage to such parts of the human body as the respiratory system, kidney, and liver. It can also be a reason for dermatitis, ulcers on the skin, and internal hemorrhaging (“Contaminants Found in Groundwater,” n.d.). Copper may penetrate groundwater because of the mineral leaching, mining and metal plating industries, and domestic waste. In high doses, it can cause damage to kidney and liver, provoke anemia, and stomach and intestinal distress (“Contaminants Found in Groundwater,” n.d.). Cyanide is an extremely poisonous substance that can get in the environment due to the improper waste disposal and as a waste product of steel processing, electroplating, synthetic fabrics, fertilizer, and plastic production. It may cause acute poisoning, provoking liver, spleen, and brain damage (“Contaminants Found in Groundwater,” n.d.). Lead gets into groundwater as a water additive, and as a result of plumbing, mining, coal, and gasoline industry.
This metal may affect the chemistry of red blood cells; it can delay mental and physical development of children and reduce attention span, as well as hearing and learning abilities in children (“Contaminants Found in Groundwater,” n.d.). Mercury may penetrate groundwater from the waste of such industries as coal mining, smelting, production of electrical equipment, usage and manufacturing pesticides, and fossil-fuel combustion (Singh & Yadava, 2003). It can cause disorders of the nervous system and acute and chronic toxicity and negatively affect kidneys (“Contaminants Found in Groundwater,” n.d.). Nickel may be naturally present in soil and water, but it also can enter the environment as a waste of alloy, stainless steel, mining, and refining industries. Consumption of water that contains this element can damage heart and liver (“Contaminants Found in Groundwater,” n.d.). Thallium can be found in the waste products of glass, pharmaceuticals, alloys, and electronic products. The test results demonstrated that this element might cause brain, kidneys, and liver damage (“Contaminants Found in Groundwater,” n.d.).
The organic class of groundwater pollution includes such matters as volatile organic compounds that might get into the groundwater as waste product of inks, plastics, gasoline, rubbers, solvents, dyes, degreasers, crude oil, preservatives, paints, insecticides, polishes, varnishes, disinfectants, pharmaceuticals, paint and spot removers, and other productions. These compounds can be a reason for liver damage, cancer, skin irritation, gastrointestinal disorder, anemia, fatigue, blurred vision, damage of nervous system, irritation of respiratory tract, and weight loss (“Contaminants Found in Groundwater,” n.d.). Pesticides such as insecticides, rodenticides, herbicides, algicides, and fungicides contaminate groundwater because of their common usage in agriculture. They can be a reason for cancer development, gastrointestinal disturbance, headaches, weakness, dizziness, numbness, and poisoning. Pesticides destroy the liver, kidneys, thyroid, nervous system, and reproductive system (“Contaminants Found in Groundwater,” n.d.).
Plasticizers, chlorinated solvents, benzopyrene, and dioxin are used as linings, components of gasoline, solvents, sealants, wood preservative, pesticides, and disinfectant and may get into the groundwater because of leaching and industrial runoff, incorrect waste disposal, and leaking storage tank. These substances can cause cancer and damage to stomach, kidneys, liver, nervous and reproductive systems (“Contaminants Found in Groundwater,” n.d.). Detergents get into the groundwater with domestic and industrial sewage and may cause a wide range of damages to human health. They can affect the immune, endocrine, and reproductive systems, cause asthma attack, allergy, cancer, and damage stomach, brain, lungs, kidneys, and liver.
It is a well-known fact that groundwater can be polluted both naturally and by human activities. As for the natural sources, such substances as arsenic, iron, chlorides, manganese, radionuclides, and sulfates might be naturally present in soil, or rocks. These substances can dissolve in groundwater and contaminate it. Such naturally appearing substances as decaying organic matter can get into the groundwater as particles. Some of these substances can be harmful to human health, especially in high concentrations; others can give water an unpleasant smell, taste, or color. Groundwater that carries high concentrations of these substances or has some of these physical characteristics is unusable without proper treatment.
The other source of the groundwater chemical pollution is improper disposal of hazardous waste. This kind of waste has to be always disposed of properly. Many various chemicals such as oils, paints and paint thinners, chemicals for garden and lawn, swimming pool and photographic chemicals, medicines, and disinfectants that are commonly used in households can pollute groundwater if disposed of in the household septic systems. Releases and spills from stored chemicals and petroleum products can also cause pollution of groundwater. Various aboveground and underground storage tanks are widely used for storage of chemical substances and petroleum products. About four millions storage tanks are kept underground in the United States, and many of them spilled into the ground over a year. Inappropriate storage of chemicals and low quality of or the end of service life of containers used for their storage is a significant problem for the groundwater. Trains and tanker trucks present another issue of chemical storage. About sixteen thousand chemical leaks occur from storage tanks, trucks, and trains each year.
The use of pesticides and fertilizers is one of the major problems of groundwater pollution. Every year, millions of tons of these chemicals are used in the USA in the agriculture industry. In addition to homeowners, farmers, utilities, businesses, and municipalities use pesticides and fertilizers. A significant amount of these chemicals get into the soil and pollute groundwater. Some kinds of pesticides can remain in the groundwater and soil for years.
Working and abandoned mines can pollute groundwater too. Precipitation can release soluble minerals from the mine wastes that contain acids, sulfides, metals, and minerals straight into the groundwater (Singh & Yadava, 2003). Moreover, abundant mines are often used as waste pits. The rest of sources of the chemical pollution of the groundwater are similar to sources of the biological pollution but with the contaminating agents being different. For instance, the leakage out of the sewer pipes and abattoir waste products can pollute groundwater with nitrogen, heavy metals, and inorganic salts.
Thermal Pollution of Groundwater
Thermal pollution is a process of increasing the temperature of groundwater. This kind of pollution can be caused by the main two reasons, which are geothermal and industrial contaminations. In many countries, heat produced by the various productions is discharged through wastewater into the environment. Such high-temperature wastes get into the shallow aquifers, which affect groundwater. Hot wastewater might create high-temperature haloes that reach aquifers under the lake (“Water Pollution,” 2005). If such a phenomenon is not controlled, it can negatively affect not only the entire life cycle of the lake, but also groundwater that is attached to it. Thermal pollution can cause the changing of biological, chemical, and physical properties of the hydrogeological system, and consequently, make the groundwater unusable.
Geothermal pollution is typical for the structurally unstable environments where high- temperature streams and gas excrete from the underground. They reach the shallow hydrogeological zones through the different fractures and warm up the groundwater, creating hot springs. Such hot springs are highly mineralized. This phenomenon can be explained by the fact that high temperature accelerates the process of dissolving the soil and geologic matter.
Radioactive Pollution of Groundwater
Radioactive pollution of the groundwater is the most dangerous among all types of pollution. This kind of pollution can be defined as a discharge of high-energy particles (radioactive substances) into the soil, air, or water as a result of accidental or done on as a consequence of human activity. The sources of this type of contamination can include such actions as detonation or testing a nuclear weapon, extraction of such radioactive matters as uranium, plutonium, and strontium, manufacturing nuclear materials for their further use in producing bombs or in nuclear power plants and accidents at such plants (“Radioactive Pollution,” 2013). Even a small amount of radioactive element can cause a serious biological outcome that can last for years and can spread around for many kilometers (Sharma, 2005). Nevertheless, some scientists suggest that radioactive active elements do not pose danger to groundwater (Sharma, 2005). However, traces of plutonium were found in groundwater thirty kilometers away from the Nevada nuclear test (Sharma, 2005). Therefore, radioactive pollution has a serious effect on the environment and should become an environmental concern of all nations.
The disposal of radioactive waste is a global problem for many countries. It must be kept away from the environment or contact with a human for hundreds if not thousands of years. It can be explained by the radioactive half-life of each element. Unfortunately, there are no reliable containers or any other ways of disposing of such waste that could last for so long. Consequently, leakages of radioactive liquid into the ground happen quite often and as a result, they pollute groundwater.
Scientists are still discovering the consequences of the 2011 Fukushima nuclear disaster in Japan (“Radioactive Pollution,” 2013). The World Health Organization reported in May 2012 that levels of radiation in the majority of areas around Japan and neighboring countries were nearly normal (“Radioactive Pollution,” 2013). Nevertheless, the tests that were done a month later demonstrated that Pacific tuna populations near California had an increased level of cesium due to the nuclear disaster in Fukushima (“Radioactive Pollution,” 2013). The seawater and groundwater samples that were studied in 2013 showed the increased levels of tritium and strontium-90 and some other radioactive isotopes, which can be associated with the accident in Japan (“Radioactive Pollution,” 2013).
Each radioactive element causes different damage to human health. For example, iodine affects the thyroid gland, cesium gets through the soft tissues, and strontium gets into calcium of bones and teeth (“Radioactive Waste and Pollution,” n.d.). All radioactive isotopes are carcinogenic. Each element has a different half-life, for instance, iodine-131 stays within the body only for a few weeks because its half-life is only eight days (“Radioactive Waste and Pollution,” n.d.). At the same time, the half-life of strontium-90 is 28.7 years, so it remains in teeth, and bones for a long period, and radioactive isotope cesium-135 has 2.3 million year half-life (“Radioactive Waste and Pollution,” n.d.).
It has been reported that such radioactive isotopes as tritium and strontium-90 were leaking from no less than two places of spent fuel pools at Indian Point into the Hudson River and groundwater since August 2005 (“Radioactive Waste and Pollution,” n.d.). Another report shows that in January 2007, strontium-90 was found in every third fish tested in Hudson River (“Radioactive Waste and Pollution,” n.d.). This statistics proves that radioactive substances may cause unfixable damage to the entire planet.
The Techniques of Cleaning Groundwater
Every country in the world faces the issue of groundwater pollution in one or another way. Cleaning water from the various pathogenic microorganisms or other harmful to human health substances can be an extremely complicated and expensive process. The results of groundwater pollution or poor quality of surface water are very serious. For instance, estuaries that were affected by the high quantity of nitrogen from the sources of groundwater have lost critical shellfish habitats (United States Environmental Protection Agency, 1993). It is known that groundwater moves very slowly and that is why its pollution often stays unnoticed for a long time. Such a phenomenon makes the process of cleaning water very complicated or even impossible. Sometimes pollution of the groundwater in the water supply is so serious that it cannot be cleaned or its cleaning is too costly and not viable; otherwise, it can be cleaned and used again. After the source of pollution is removed or taken under control, the polluted water can be treated in different ways.
For example, one of the solutions is restraining the pollutant to prevent its movement, pumping out polluted water, purifying it and then returning it back to the aquifer. The other solution is treating the water or the pollutant, but leaving the groundwater in place, or leaving everything as it is, allowing the pollutant to reduce by itself but at the same time control the source appropriately (United States Environmental Protection Agency, 1993).
Choosing the appropriate cleaning technology has to be based on several specific factors such as the goal of cleaning, evaluation of the potential risk and estimation of the level of protection of human and environment. Different technologies can be effectively applied for the different pollutants. Often several different technologies are combined for the more effective result that depends on the local hydrogeological conditions. The high price on the complicity of the majority of the processes, some people choose to abandon the polluted wall and use other sources than cleaning the existing one. Thus, it might create the problem of improperly abandoned wells.
Groundwater can be considered the best source of the drinking water, because of the purification properties of the soil and its saturation with various minerals, groundwater is not only some kind of liquid that quenches one’s thirst but it can also be a great source of minerals. It can be used for many purposes in the various aspects of human life. It is the main source of water for many developing countries. An aquifer constitutes a natural reservoir of high-quality water. Even though groundwater is more protected from the outdoor environment than the surface water, it appears to be a subject to pollution. Unfortunately, with a constant growth of industry, increasing population, and megalopolises development, pollution of the groundwater becomes a public concern worldwide.
Groundwater pollution that was discussed in this work was classified by the sources of its pollution into biological, chemical, thermal, and radioactive. Biological pollution contaminates the groundwater with various pathogenic microorganisms that might cause the outbreak of the different diseases. The main sources of this kind of pollution are abattoirs and fecal waste. The chemical pollution changes the chemical composition of water. This kind of groundwater pollution might fill the water with different organic and inorganic chemical elements that can be poisonous to humans. The main source of such pollution is the industrial and agricultural waste. The thermal pollution of the groundwater can be considered the least dangerous among others.
This kind of pollution changes the temperature of the groundwater if not controlled. Consequently, it might change the physical, chemical, and biological properties of the groundwater. Such pollution can be caused by industrial waste or naturally. Radioactive pollution contaminates groundwater with radioactive isotopes. The main sources of the radioactive pollution are the nuclear stations, extraction of the radioactive matter, leakage of radioactive materials, and tests of the nuclear weapons. The effect of such pollution can last for years. It is extremely harmful to humans and the environment in general. There are not many ways of cleaning the sources of the groundwater. They might be extremely expensive and cannot be effective for all kinds of pollution. That is why it is much easier to prevent contamination than getting rid of it.
During studying this subject, I learned about different microorganisms, matter, and elements and their impact on the health and quality of human life. I also came to a conclusion that if every individual does whatever he or she can to avoid groundwater pollution, the situation around the world will improve drastically. Only together, can we make a difference.