Question

Give reasons for the following.

Surface run-offs from agricultural fields lead to death of nearby aquatic life.

Answer 1

Surface run-offs from agricultural fields lead to death of nearby aquatic life because:

1. Runoff carries massive amounts of chemical fertilizers, nitrates, and phosphates, acting as a prominent source of agricultural water pollution.
2. This sudden nutrient influx triggers rapid, uncontrolled multiplication of surface algae, initiating severe aquatic eutrophication.
3. The thick layer of surface algae blocks essential sunlight, destroying submerged aquatic plants that naturally generate oxygen.
4. When the algae die, decomposing microbes consume extreme amounts of dissolved oxygen to break down the organic matter.
5. This severe oxygen depletion creates hypoxic dead zones, while toxic pesticide runoff directly poisons vulnerable fish and macroinvertebrates.