What is water pollution

Water pollution................ (to be) any chemical, physical or biological change in the quality of water. It has a harmful effect on any living thing that................ (to drink) or................ (to use) or lives in it. When humans drink polluted water it often................ (to have) serious effects on their health.

There are several classes of water pollutants. The first are disease-causing agents, such as bacteria, viruses and untreated waste.

A second category of water pollutants is oxygen-demanding wastes; wastes that can................ (to decompose) by oxygen-requiring bacteria. This causes other organisms in the water, such as fish, to die.

A third class of water pollutants................ (to be) acids, salts and toxic metals. Large quantities of these compounds will make water unfit to drink and................ (to cause) the death of aquatic life.

Water can also................ (to pollute) by a number of organic compounds such as oil, plastics and pesticides, which are harmful to humans and all plants and animals in the water.

It................ (to recognize) that water pollution................ (to cause) usually by human activities.

During the lesson there was a mentioning of some problems connected with an ever greater hazard not only to health but the whole life on earth – water pollution. They are: acid rains; chemical pollution of water (produced by pesticides, vehicle fluids or industrial waste); biological pollution (caused by viruses or bacteria). Make a short report about one of them. Suggest the ways of preventing pollution of water.

You may do it as a “Personal records”, “PowerPoint Presentation”, assay etc.