Question

How does river water get polluted? Explain​

Answer 1

$\sf\red{Answer:-}$If large amounts of fertilizers or farm waste drain into a river the concentration of nitrate and phosphate in the water increases considerably. Algae use these substances to grow and multiply rapidly turning the water green. This massive growth of algae, called eutrophication, leads to pollution

Answer 2

Answer:

Chemical waste from factories is sometime dumped into river and lakes, or directly into the ground. Pesticides (chemical that kills insect) applied to farm land enter surface water or ground water, often in large quantities. Some pollutants slowly break down into harmless chemicals.