Water pollution and its control


Water makes up 70% of the earth but the bioavailability is a mere 3%. Bioavailability is the overall amount of water fit for domestic use. Bioavailability is directly proportional to the degree of water pollution in a given reservoir of water. Water pollution is one of the growing issues in many countries.  "Water pollution refers to the pollution of various water sources and reservoirs (water bodies such as canals, tanks, ponds, rivers, and oceans) becasue of pollutants".


Table of contents

  1. Introduction

  2. Water pollutants

  3. Effects of water pollution

  4. Prevention and management of water pollution


Water pollutants

A pollutant is a causative agent, the most common water pollutants are the domestic wastes, industrial effluents, wastes generated from thermal plants, agricultural wastes, biological wastes generated by plants and animals, and oil leakage from ships. Water pollutants can be chemical, microbial or physical in nature but in most cases, chemical agents are being diverted into rivers, ponds, and other water reservoirs. Most common toxic chemicals that pollute water are sulphur, carbon, ammonia, etc. In an aquatic ecosystem, water pollution is caused by algae, bacteria and fungal organisms.

  1. Domestic Sewage: Household human activities generate a lot of waste known as domestic sewage. Around 6 billion kilograms of garbage is released into the oceans every year. Domestic sewage contains biodegradable organic matter formed by bacterial decomposition. Microbes involved in the biological decomposition of organic wastes consume a lot of oxygen available in the water. Consequently, many aquatic species die becasue of oxygen deficiency. Aquatic oxygen deficit is a result of gradual depletion of available oxygen levels in the water. On the other hand, the non-biodegradable impurities such as suspended soil, colloidal wastes and dissolved materials released into ponds, rivers and oceans make water worse. Industrial effluents rich in some chemical-based salts; nitrates and phosphates combine with the toxic metals like lead and mercury result in the death of fish and many other organisms. The proportion of the organic compounds in polluted water is very low making it odorous, distasteful and unfit for use.

  2. Agricultural wastage: Agriculture is a great contributor of toxic wastes. Various farming activities result in the toxic byproducts. Modern farming is responsible to release the most deadly chemicals into the water. As a result of pesticides, weedicide sprays and chemical-based manures, water loses its quality. The sprays also cause soil pollution to make it infertile. When water flows through such soil, the chemicals will move to the water bodies like tanks, ponds, rivers, etc. Sewage water and agricultural runoff have nutrients like nitrogen and phosphorus, which aids in the development and growth of plankton and such a process is called eutrophication. Eutrophication results in the depletion of oxygen levels in the water bodies that kill the aquatic fauna. The presence of multiple nutrients in waters results in the excessive growth of planktonic algae, and this phenomenon is known as an algal bloom. Algal bloom gives a distinct colour to the water bodies which again is not a good sign.

  3. Industrial Effluents: Some of the toxic substances present in industrial waste causes biomagnification. It is a process where the amounts of toxic substances passed on from one trophic level to the successive level will be multiplied. This is because the toxic substances accumulated by an organism cannot be metabolized or excreted, instead, it automatically passed on to the higher trophic level. If we take mercury and DDT, the concentration of DDT will be increased at every successive trophic levels. If the DDT levels are at 0.003 ppb ( parts per billion) in water, it can reach 25 ppm by the time the chemicals enter the birds and this is called bio-magnification.  When DDT goes beyond certain levels in our system, they are very potent to cause destruction of species and many deadly diseases. Increased levels of DDT can disturb calcium metabolism in birds resulting in thinning of their eggshell and premature breaking so, the ultimate result is the decline in bird populations. DDT has the ability to reduce fat levels in the body. It also interferes with brain function and vital organs' health.


Effects of water pollution

It is always necessary to control water pollution as it can also lead to diseases like jaundice, cholera, typhoid, dysentery, dengue, malaria, etc many of which are very hard to cure. Any form of water pollution results in the depletion of oxygen levels in the water. Such a phenomenon will further lead to the death of aquatic plants and animals as the bio-availability of oxygen is low in the water bodies. Death of biological organisms in the water, in turn, result in biodiversity destruction. Water pollution can lead to chronic diseases of the gastrointestinal system, skin and some other infectious diseases. The crops grown from such water are also toxic which can have a long-term influence on the lifespan of an individual. 


Prevention and management of water pollution

It is very important to control and manage the pollutants in order to save the existing species. The pollution must be prevented at source; avoid activities that generate a lot of unwanted pollutants. Biological methods like growing invasive plant water hyacinth will help to control and remove BOD, suspended solids, nutrients such as phosphorous and nitrogen. Some of the water pollution management measures are:

  1. All the domestic wastes and wastewater must be treated before releasing them into the rivers and lakes.

  2. Drinking water and irrigation water must be separated and treated accordingly.

  3. All the water bodies must be kept clean through a scheduled cleaning 

  4. Drinking water reservoirs must not be used for washing cattle, bathing, and other purposes. 

  5. Planting trees help to reduce acid rain and pollution of groundwater.

  6. Rainwater harvesting is a must because it will conserve the water and reduce wastage of freshwater.




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