The impact of human activities on the earth has become noticeable and significant during the last century resulting from:
- Increasing population - this resulted from increased food supply and improved health care.
- Economic factors - the rise in the standard of living resulted in increased demand for consumer items. (cars, etc...)
- Requirements of industry (the raw materials, increased manufacturing capacity) and as a result there were greatly increased levels of pollution (including heavy metals and radioactivity) some of which are extremely toxic and long lasting. Any benefits to the quality of life / standard of living have to be set against the economic results.
There are two main sources of water pollution:
- Heat - this results from the need to fuel machinery etc... in power stations, industrial manufacturing etc... Huge quantities of warm water discharged into rivers cause local environmental disturbances, either by allowing in "alien species" from tropical seas, or causing a fall in the amount of dissolved nutrients
- Toxic compounds - of which there are two main types. Firstly, actual poisons from industry in the form of chemicals and secondly, organic compounds derived from sewage, industry and also chemical fertilisers. These chemicals have indirect effects which are damaging either as toxic chemicals or by causing eutrophication.
Leaching / Eutrophication