Why does a temperate zone support many varieties of organisms

Atown is built on the banks of a small lake on the edge of a desert. after some time, the townspeople discover that water from the lake has become too polluted to use. describe one way that the lake may have been contaminated by the actions of the townspeople, and explain how the townspeople can remediate this problem.

What is the speed of sound in water

What is the pattern of urbanisation around the word?