Contamination of water bodies because of the discharge of pollutants into them is known as water pollution. Water pollution may severely affect human, plant, and animal life. Effects of Water Pollution are
Effects of Water Pollution on Marine Life
The effect of water pollution on marine animals and plants is visible in two phenomena—eutrophication and biomagnification.
Eutrophication:
It is a process in which oxygen begins to deplete from water bodies either naturally or because of human activities. Nutrients and chemicals are discharged into water bodies through sewage and effluents. Accumulation of these into water bodies results in the growth of phytoplankton and algae. This obstructs the penetration of oxygen and sunlight into water bodies which may result in the death of aquatic organisms.
Biomagnification:
When the quantities of harmful substances such as pesticides and insecticides increase in the food chain of marine and aquatic organisms and are in turn consumed by other living beings, it is known as biomagnification.
Effects of Water Pollution on Human Health
- Pathogens are disease-causing bacteria present in wastewater. When contaminated water is consumed, the pathogens enter the human body. It may cause various water-borne diseases such as typhoid, cholera, diarrhoea, dysentery and jaundice.
- Metals such as lead, mercury, and cadmium dissolved in water may cause several diseases if they enter the human body. When water contaminated with cadmium was consumed by the Japanese, they were affected by a disease called itai-itai. Similarly, a disease known as Minamata affected the Japanese after they consumed fish that had a large concentration of mercury.
Other Effects of Water Pollution
- When phosphorus and nitrates from fertilizers are disposed of in water bodies, they promote the growth of algae. The presence of algae in water bodies in a large number reduces the amount of dissolved oxygen in water resulting in the death of fish and other water organisms.
- Industrial effluents include chemicals such as mercury, lead, and cadmium. When these chemicals reach the human body through the consumption of fish, they may cause irritation, insomnia, and nervous disorders, which may also affect the brain.
- Thermal pollution increases the temperature of the water which in turn reduces the level of oxygen in the water. This results in the death of many species of fish. Oil drilling and oil spills contaminate seawater which may also lead to the death of marine organisms.
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