What is Water Pollution?
According to wikipedia, “Water pollution is the contamination of water bodies (e.g. lakes, rivers, oceans, aquifers and groundwater), usually as a result of human activities.”
Natural water bodies like lakes, rivers, oceans, etc., get contaminated to give rise to water pollution. When pollutants are emptied into water bodies without proper detoxification treatment, water pollution occurs.
Around 70% of earth’s surface is occupied by water. So when the water bodies get polluted, they contribute to a large percentage of pollution on earth. The primary causes of water pollution are human activities and industrialization.
Before the 19th century Industrial Revolution, water pollution was not reported. With the ever-increasing population, water pollution has been on the rise. Water pollution is more harmful to the aquatic lives living in the water bodies and human lives.
Most of the times, water pollution is a reversible phenomenon. However to reverse extensive water pollution, huge investment of time and money is required. To understand the harmful effects of water pollution, it is important to first look into the types and causes of water pollution. Listed below are some of the major types of water pollution, which gives us a complete picture of the subject.
Major Types of Water Pollution
A. Based on origin of pollution
Based on origin of pollution, they can be of different types such as (1) Point source, and (2)Non-point source.
Point source water pollution:
A point source refers to one single distinguishable source of pollution. Point source can be a drainage source, sewage pipe, etc. Industrial waste discharge comes under point source of water pollution. Mostly a point source involves discharge of toxic effluents at a single point and thus intensifying the water pollution even more in that area. To prevent industrial effluent water pollution, treatment plants should be installed prior to the discharge point.
Non-point source water pollution:
Also called as ‘diffuse’ pollution source since it occurs in a larger area and usually is not caused by one source alone. Also, non-point sources cause more of a diluted effect on water bodies since the point of concentration of discharge is spread over a larger area when compared to point source. Setting up treatment plant is of no use in this type of pollution. Large scale control methods become essential to prevent non-point sourced water pollution.
B. Based on the water source
Based on the water source, there can be (1) Ground water pollution, and (2) Surface water pollution.
Ground water pollution (groundwater contamination) is seen to happen when the pollutants from the ground seep into groundwater. Water is also present in soil or underground permeable rock structures called aquifers. Pollution of this underground water is called groundwater pollution. Any water found under the surface of the earth refers to ground water. Ground water pollution may occur from a variety of sources ranging from physical to bacteriological. It can be because of both natural as well as man-made sources.
Groundwater pollutants can be either from point source or non-point source. A pollutant from a fixed source like sewage pipe is point source whereas pesticides and fertilizers, which come from a wide region are of the non-point source category. Ground water treatment to make it pollution free is quite tedious and expensive.
- Harmful microorganisms: Feces contain pathogens, which can seep into the ground water to pollute it. Various bacteria, protozoa, helminths and viruses are present in polluted groundwater. Such polluted groundwater if consumed by humans may lead to deadly diseases like cholera.
- Nitrate: Nitrates can pollute groundwater considerably. They tend to mix with the groundwater due to excessive use of fertilizers and even manure, by farmers. Most of the nitrates in the fertilizers seep in the soil to pollute ground water. Nitrates are highly water-soluble and easily dissolve in ground water. Using too much of nitrogen containing fertilizers for agriculture is a major cause of ground water pollution.
- Volatile organic compounds: Volatile organic compounds (VOCs) are another source of ground water pollution. Industrial effluent discharge and fumes when not properly managed, leads to this type of pollution. Ground water when tested were found with VOCs in good quantities.
- Arsenic: The aquifers present below the ground sometimes can be harmful when their sediments generate arsenic. This is due to microbial action occurring in anaerobic conditions. This naturally occurring ground water pollutant may also prove to be very harmful.
- Fluoride: In certain areas, naturally occurring fluoride is in high levels in groundwater. This is another natural water pollutant like arsenic. This high-fluoride ground water if consumed may harm human dental health.
- Other pollutants: Organic pollutants like pesticides, insecticides, petroleum hydrocarbons, etc., are also significant ground water pollutants. Inorganic pollutants present in ground water are heavy metals, toxic metals, ammonia, etc.
When solid industrial wastes are disposed on the ground, the rainwater dissolves these materials and seep in the ground water to pollute it.
Surface Water Pollution:
Surface water like rivers, oceans and lakes when get polluted, this phenomenon is called surface water pollution. Surface waters are basically the water bodies that are present on the earth`s surface. Many of the pollutants are common for ground water and surface water pollution. There is also an interaction and exchange between ground water and surface water in lot of scenarios since groundwater is connected to rivers and lakes.
Surface water pollution are of the following types:
1. Thermal pollution: When water ambient temperature is altered by external pollutants, it is termed as thermal pollution. This degrades the water quality by decreasing dissolved oxygen in water. Two main causes of thermal pollution are industries, power plants and urban water runoff. Contaminated storm and rain water, which gets washed off roads and highways is called as urban runoff. Industries and power plants use water as coolants in their activities and release the toxic heated water back to the natural water bodies. Aquatic lives are greatly affected by thermal pollution.
2. Marine Pollution: Marine pollution or oceanic water pollution is caused from a wide variety of sources. Industrial chemicals, plastics, agricultural and domestic wastes in the form of sewage are some of the factors affecting marine pollution. Land and air pollution both are contributing factors to marine pollution. Inland and deep sea mining for metals like gold also may lead to marine pollution. Ships and other water transports also contribute towards contaminating marine water.
3. Oil spills: This is a major cause of water pollution in oceans. Oil spills occur very frequently in marine water from passenger and cargo ships. Being immiscible in water, oil forms an impermeable thick layer on the water surface, thus harming aquatic life. Oil spills usually occur from engine leaks and cargo residues of crude oil. Polycyclic aromatic hydrocarbon (PAH), a chemical present in crude oil is a menace. They are extremely hard to clean and tend to last for ages in the marine waters.
C. More forms of Water Pollution.
1. Chemical pollution: Chemical pollution occurs when large amounts of harmful chemicals are released into the atmosphere or water bodies. This has adverse effect on our ecosystems and health. Various sources of Chemical Pollution have been identified and are listed below:
- Agricultural chemical pollution – Wide varieties of chemical pesticides and insecticides are used in agriculture . This way the crops stay protected but the water gets polluted. The dangerous chemicals from the pesticides can leach into the groundwater from the soil. Also some water-soluble ones can also runoff to contaminate the nearby surface water sources.
- Transportation – Vehicular exhausts release high amounts of carbon dioxide into the atmosphere. This not only gives rise to global warming but also leads to acidification of water in the water bodies (due to dissolved carbon dioxide). Water transports like ships are also responsible for chemical pollution. Oil spills occurring from ships transporting crude oil leads to serious amount of water pollution as discussed above.
- Industrial chemical pollution: Irresponsible discharge of industrial effluents into water bodies are a major cause of chemical water pollution. Heavy and toxic metals contaminants along with dangerous solvents from industrial processes turn the water in the water bodies highly poisonous for living organisms living in water.
2. Oxygen depletion in water: This phenomenon of water pollution is also known as aquatic hypoxia. Factors that are responsible for this adverse situation are agricultural pollution and industrial as well as urban runoff. These kinds of pollution lead to increased discharge of phosphorous and nitrogenous nutrients in the water. When a lot of biodegradable matter finds its way in water, it increases the microorganism population, which then use up more oxygen in the water. Thus, the polluted rivers, lakes, ponds and oceans land up overfeeding and harboring aquatic microorganisms on their surfaces. Algal blooms grow generously on the water surfaces thus harming the oxygen supply for the aquatic life. Even after the algae die and sink to the bottom of the water body, they serve as nutritional sources for various bacteria, who feed on them by taking in dissolved oxygen from the water. When oxygen depletion occurs, aerobic organisms die while the anaerobic organisms flourish to form harmful toxins like ammonia and sulfides. The regions of oceans where there is acute depletion of oxygen, are called as dead zones. These areas can be easily identified when dead fish float on the surface of the water in dead zones.
3. Suspended matter pollution: Pollutants which are insoluble in water and stay suspended on the water surface are known as suspended matter pollutants. This is because their molecules are way too big to dissolve in the water molecules. The suspended particles eventually get heavier over time and sink to the bed of water bodies in the form of thick silt at the bottom. This harms the aquatic life living on the river or ocean beds. Biodegradable substances are also found suspended in water. Suspended matter directly effects the water bodies by causing physical damage to the marine life and by blocking visibility of the living organisms as well. They also look unappealing visually. It`s other affects include turbidity. Increase in the water turbidity tends to decrease activities like photosynthesis. Turbidity and suspended matter pollutants are some of the visible indicators of water pollution. These suspended particles originate from soil and urban runoff, industrial discharges, or algal blooms.
4. Atmospheric pollution: Increased atmospheric pollution also contribute to water pollution. Sulphur dioxide and nitrogen oxide are harmful air pollutants, which when dissolve with atmospheric water, forms a toxic product which rains down on earth as acid rain. Acid rain showers on water bodies causing water pollution and killing aquatic organisms. Combustion of coal releases considerable amount of mercury in the air which then dissolves in water bodies to cause water pollution. Mercury is a non-biodegradable chemical and it is extremely difficult to clean up water and air contaminated with mercury. Global warming due to increased air pollution increases the temperature of the water bodies causing water pollution and harming aquatic organisms.
5. Plastic pollution: Plastic is a chemical, which is one of the major toxic pollutants. It is a big cause of water pollution. Domestic garbage disposals in water bodies have enormous number of plastic items. They float on the water and choke aquatic animals. Also, commercial plastic fishing nets contribute to water pollution. When the plastic nets remain in water for long periods of time, the toxic chemicals leach into the water. Pieces of broken net can also remain in water forever and harm the living aquatic organisms.
6. Nutrient water pollution: Cattle rearing causes water pollution as well. Washing and bathing cattle in river water or ponds lead to nutrient water pollution along with their excreta waste.
7. Lead poisoning: Lead leaching from water pipes may lead to water pollution. Most of the plumbing material used is lead and lead renders the water poisonous if leached into the water. Lead poisoning causes a lot of health hazards.
8. Sewage: Sewage is the liquid sanitation waste consisting of human feces, urine and other dirty water which arises from various human activities like washing, bathing and cleaning. In many under developed countries and developing countries, sewage is released into local water bodies. Sewage water requires to be treated before it’s dumping into any water body. Untreated sewage causes serious water pollution. It harms human as well as aquatic lives, threatening human livelihood. It deplete oxygen levels in water and increases the nutrient load significantly. Waste water and sewage need proper treated disposal to prevent water pollution.
9. Radioactive water pollution: Radioactive waste is completely human-made. Careless disposal of radioactive waste may harm living beings for generations. It can pollute the water bodies and traces of it has been found in the ground water. Accidental release of radioactive substances from nuclear power plants might find their way to the water bodies and create havoc.
10. Landfills or garbage dumps: Garbage dumping on the ground lead to ground water pollution. All the wastes seep into the ground. Also, during rains they might be swept to surface water bodies as well. Landfills are areas where huge pile of garbage are kept for longer times. This is a potential source of concentrated water pollution.
Water pollution is a grave problem in the modern times of industrialization and urbanization. Awareness and precautions are the main ingredients to solve this problem. Most of the human diseases are water-borne and thus water pollution is a serious threat to human well-being. We should take care to not treat the natural water bodies as our dumping ground. Treatment plants should be established and functional to prevent water pollution. Regulatory authorities should format and implement strict rules for industries for their effluent disposal techniques. Water pollution can be reversed if necessary action plans are proposed and executed. However this should not make us take things for granted before we realize it is too late.
Domestic sewage disposal should also be strictly monitored. Good sanitation measures in villages and cities will prevent ground water as well as surface water pollution. Pit-latrines should be avoided because it causes major ground water pollution.
Agricultural practices should be modified to prevent water pollution since it has serious threat towards eutrophication of water bodies and towards ground water pollution. Animals should not be allowed to graze too close to water bodies, to prevent nutritional load pollution.
Water is the most important natural resource which is mandatory for survival of living beings. We should not deplete or pollute this resource and fix the damages done at the earliest. The seriousness of the problem need to be understood since water pollution is a very commonly occurring phenomenon.
Also read about Water Pollution in Wikipedia.