Here is a list of the main types of pollution in rivers and seas. A description is given next to each:
Agricultural run-off
Nitrates and phosphate fertilisers cause algae to grow rapidly. The algae uses up all the oxygen as it is rapidly growing. This leaves no oxygen left for plants and animals. As well as this problem, pesticides reaching rivers and seas can kill animal life.
Industrial discharge
This could be to blame for the general decline in the number of mammals (mainly Wales and dolphins) and also deformed fish. Industrial discharge also contains metals such as mercury which can have effects on the nervous system and lead to kidney disease.
Visual pollution on beaches
The main problem with this type of pollution is the health risk to humans. Mainly causes by sewage and oil. Bathers can get upset stomachs and eye infections. In the short term there is a risk of typhoid and salmonella and polio in the long term.
Sewage sludge
This includes nitrates from farms and metals. The long term effects of sewage sludge are not yet known.
Oil
This spoils beaches and more importantly kills wildlife. Caused by oil leaks but more often tankers washing out at sea.
Atmospheric pollution
This includes radioactive fallout and acid rain. Acid rain damages statues and buildings and also has effects on rivers and ponds.