1.Pesticides
Pesticides that are applied to and certain
animals may drip onto the soil are carried into local stream and rivers by
surface runoff. They can also drain down into groundwater, this contaminates
the water , affecting the living organisms in the water and making the water
unsafe for drinking
2. Fertilizers (nutrients)
Many courses of pollution such as sewage,
manure and chemical fertilizer, contain nutrients such as nitrates and
phosphates.In excess level, the nutrients cause excessive
growth of aquatic plant and algae. This is known as eutrophication.
Eutrophication clogs waterways and blocks light from
penetrating into the deeper water. When the aquatic plants and the algae die,
they use up dissolve oxygen as they decompose. This lower the amount of oxygen
available in the water for aquatic organisms such areas are commonly called Dead zones
3. Sediments
When forests are cleared, the root system that
previously held the soil in place die. This exposes the soil to erosion by
running water, the eroded sediments is deposited in nearly stream, rivers, and
lakes. The sediments effects fish and other aquatic life in the water bodies.
Poor farming practice also expose the soil to
pollution, thereby contributing to sediments pollution in water.
4. Industrial process
Most of the water that are used in production
process in industrial is thereafter discharged into water bodies. This waste
water may contain acids, alkalis, salts, ionics, chemicals, oils and, in some
cases harmful bacteria. These substances affect the quality of water and
interfere with the lives of water organisms.
5. Oil spills
Oil spills in oceans cause major water
pollution and problem for local wildlife and fisherman. A spill forms a thin
layer of oil on the surface of water affecting the exchange of gases between
the water and the atmosphere.
Land based petroleum pollution is also carried
into waterways by rainwater runoff. This includes drips of oil, fuel and fluid
from vehicles, and drips from industrial machinery. Drilling and extraction
operation from oil and gas can also contaminate coastal waters and groundwater.
6. Sewage
In developing countries, about 90% of waste
water is discharged directly into rivers and streams without being treated.
Untreated sewage wastes gives rise to disease causing organisms in water
bodies. Leaking septic tanks and other sources of sewage can cause
groundwater and stream water contamination.
7. Mining activities
Mining causes water pollution in a number of
ways, the include the following;
The mining process exposes heavy metals and
sulphur compound that were previously buried in the earth. Rainwater leaches
these compound out of the exposed earth, resulting in acid drainage and heavy
metal pollution that cn continue long after the mining operations have ceased.