Give a reason for each of the following:

Run off from fields leads to death in adjacent water bodies.

Run off from fields leads to death in adjacent water bodies because the fertilisers and pesticides used in the fields have chemicals. When they reach the water bodies, the toxins present in the waste can kill aquatic organisms directly by sufficiently changing the pH of water, covering the water surface and causing a reduction in dissolved oxygen. The aquatic organisms may also become victims of bio-magnification and bio-accumulation.