Water pollution:-

Any undesirable change in composition of water which is harmful for living organism.

• About 99.9% water is pure, only 0.1% impurity make unfit for domestic purposes.

0.1% impurity include:

1. Suspended matter:- Clay, sand, slit.

2. Colloidal matter:- faecal matter, paper, cloth.

3. Dissolved nutrient:- ammonia, nitrate, phosphorous etc.

 

BOD:- Biochemical oxygen demand or Biological oxygen demand.

The amount of oxygen in milligram required to completely metabolise one litre of water in 5 days at 20^oC by micro-organism.

More BOD, more Contaminated water,

Zero BOD, means Pure water.

Algal Bloom:- Excessive growth of planktonic algal due to presence of large no. of nutrients in water body.

Algal bloom cause distinct colour  on smell water.

Some bloom forming algal are highly toxic to human and other animal.

Eichornia  is world’s most problematic weed called Terror of Bengal. It has excessive reproductive capability  i.e. more than our removed ability.

Biomagnification or Bio-Amplification:-

Amount of toxicant increases successively with increase in tropical level through food chain. The maxi concentration of toxicant present in top consumer Bio-magnification is shown in non-degradable pollutant like DDT.

Conc. of DDT is max. in Birds which interferes with calcium metabolism in bird, and causes thning of egg shell, results in premolar hatching of egg result in declination in bird population.

Eutrophication:- Natural ageing of water body due to nutrient enrichment.

If eutrophication take place. By phosphate or Nitrate or hot water. Then it is called cultural or accelerated eutrophication.