Pollution of water bodies has adversely affected the growth of aquatic fauna and flora. Water is polluted by four substances: traditional organic waste, waste generated from an industrial process, chemical agents of fertilizers and pesticides used for crop protection and silt from degraded catchments. In this article, we will discuss the causes of water pollution at the environment.
What is Water Pollution?
Water pollution means the contamination of water due to any external material, or in other words introduction of something to natural water, which makes it unsuitable for human consumption.
According to WHO, “Water pollution means, due to natural or any other sources, the entrance of those elements in water which poilute it, make it harmful for life, make it more salty, decrease the quantity of O,, destroyilts taste and spread communicable diseases.”
According to National Pollution Control Board (NPCB), “Water pollution means the changes in the physical, chemical or biological virtue of water which occur due to the mingling of shit or other industrial waste material or any other element. Such water is harmful for human health and it cannot be used for domestic, professional, industrial or agricultural purpose.” Water pollution is when water becomes impure, unfit for drinking and harmful to health.
Unforgettable Causes of Water Pollution
Water pollution is caused by several sources, which are not independent but interact with one another. Generally, one or two factors become prominent and may be considered the primary source of water pollution. There are various causes of water pollution are:
1. Natural Sources
There are certain natural elements which is the main reason of water pollution. These are gases, soil, mineral, humus material, and waste created by animals and other organisms in the water. The brown and dirty water results from mud mixed in the water, which becomes clear after some time. During rains, one can observe the available imprint of soil on the water of rivers, tanks and other water bodies.
In the same way, different types of natural, suspended and colloidal impurities are also in the water. These elements may be organic or inorganic and may even be harmful. Minerals like sodium, potassium, magnesium, iron, etc., are also present in the water, and if their quantity is more than the permissible limit, these are harmful. Some poisonous minerals, such as nickel, beryllium, cobalt, lead, mercury cadmium, etc., are very harmful and are responsible for pollution.
Colloidal impurities are also there in the water. These elements may be organic or inorganic and may even be harmful. Minerals like sodium, potassium, magnesium, iron, etc., are also present in the water, and if their quantity is more than the permissible limit, these are harmful. Some poisonous minerals, such as nickel, beryllium, cobalt, lead, mercury cadmium, etc., are very harmful and are responsible for pollution.
2. Humans Sources
The rapid growth of population, urbanization, industrialization and increasing use of chemicals reasons for water pollution. Major human sources of water pollution are:
i. Domestic Effluents and Sewage
Men use large amounts of water for their domestic intent, such as drinking, preparing food, bathing, cooling etc., use a large amount of water. About 70 to 80 per cent of the water used by the men for their daily purposes is discharged and drained out, which through municipal drains, pours into many cases, a river, tank or lake. This water is known as domestic wastewater, which, when other waste materials such as paper detergents, clothes and other waste materials are mixed, is known as municipal waste or sewage.
Domestic wastewater and sewage are the main sources of water pollution. This is the inevitable and unfortunate fallout of urbanization. As it decays, this organic waste depletes the water’s oxygen and upsets the aquatic ecosystem’s natural balance. The sewage receives no treatment before discharge. In Delhi alone, 120 crore litres of water is consumed daily, out of which 96 crore wastewater is drained into the Yamuna river through 17 big drains. All 47 towns on the river Ganga drain their sewage into it. With population growth, the quantity of wastewater is also increasing, in addition to the production of large quantities of sewage.
ii. Industrial Effluents
Industrial activities are the main causes of water pollution, it generate a wide variety of waste products, which are generally discharged into water courses. Major contributors are pulp and paper, chemicals, petrochemicals and refining, metal-working, food processing, textile, distillery etc. The wastes, broadly categorized as heavy metals or synthetic organic compounds, reach bodies of water through direct discharge or leaching from waste dumps.
iii. Agricultural Effluents
The use of various types of pesticides and insecticides in agriculture causes of water pollution. Their presence in water is highly toxic to man and animals because they have a high persistence capacity, i.e., their residues remain for long periods. Farm animal wastes often pose serious problems of odour and water pollution. These wastes also contain pathogenic organisms which get to humans.
Quick Point on Ground Water Pollution
Groundwater forms about 6.2% of the total water on planet earth and is about 30 times more than surface water (streams, lakes and estuaries). The ground is less prone to pollution as the soil mantle through which water passes helps to retain various contaminants due to its cation exchange capacity. However, there are several potential sources of groundwater pollution. Septic tanks, industry (textile, chemical, tanneries), deep well injection, mining etc., are mainly responsible for groundwater pollution, which is irreversible. Groundwater pollution with arsenic, fluoride and nitrate poses serious health hazards.
Eutrophication of Lakes
A lake or a pond with clear water contains minimal nutrients and supports small populations of aquatic organisms. Eutrophication enriches a standing water body with nutrients such as phosphorus and nitrogen. It occurs when sewage and fertilizer run-off bring large amounts of nutrients into the water.
In eutrophic lakes, there is an increase in photosynthetic activity. This results in cloudy water covered with a slimy and smelly mat of algae and cyanobacteria. When excessive algae die and deposit on the bottom of the late and decompose. Since this process uses up much-dissolved oxygen, some fish species die. They are replaced by other species that can tolerate lesser amounts of oxygen.
Eutrophication is undesirable since it changes the species’ mix in the water body. Reducing phosphorus and nitrogen inputs is the best way of controlling eutrophication.