Correct Answer - Option 1 : run off from agricultural field and sewage pollution
Explanation:
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Eutrophication refers to the addition of artificial or non-artificial substances, such as nitrates and phosphates, through fertilizers or sewage, to a freshwater system.
- It can be anthropogenic or natural.
- It leads to an increase in the primary productivity of the water body or “bloom” of phytoplankton.
- The overgrowth causes the loss of oxygen in the water leading to severe reductions in fish and other animal populations.
- Eutrophication escalates rapidly when high nutrients from fertilizers, domestic and industrial wastes, urban drainage, detergents and animal, sediments enter water streams.
- When the process of Eutrophication is increased by human activities, it is called cultural Eutrophication.
Effects:
They can have a large impact on the health of rivers and estuaries such as increased production of algae and aquatic plants, depletion of fish species, general deterioration of water quality.
