Question

What are the major sources of water pollution in our country?

Answer 1

1. Domestic Sewage:
   • Untreated or partially treated sewage discharged into water bodies is a major source of pollution.
   • Contains decomposable organic matter which raises the Biochemical Oxygen Demand (BOD), decreasing dissolved oxygen (DO) in water and harming aquatic life.
   • Also contains pathogenic organisms and putrescible materials causing foul smell and waterborne diseases like cholera, typhoid, and dysentery.
2. Industrial Wastes:
   • Various industries such as paper, textile, cement, chemical, tanneries, distilleries, steel mills, etc., release wastes into rivers and lakes.
   • These wastes may contain toxic heavy metals like mercury, cadmium, chromium, copper, zinc, and pathogens like anthrax bacilli.
   • Mercury causes nervous system abnormalities, cadmium and chromium are lethal to marine organisms, and tannery wastes are highly polluting.
   • Industrial effluents often consume much oxygen, exacerbating oxygen depletion.
3. Agricultural Chemicals:
   • Use of pesticides such as DDT (chlorinated hydrocarbons) and artificial fertilizers cause runoffs carrying chemicals into water bodies.
   • These chemicals bioaccumulate and biomagnify through the food chain, affecting hormonal balance and causing mutations and cancers in humans.
   • They also depress photosynthesis in aquatic plants, disrupting the ecosystem.
4. Thermal Pollution:
   • Power plants and industries use river or lake water for cooling and discharge it back with increased temperature.
   • The rise in water temperature inhibits growth of aquatic life and alters ecosystem dynamics.
5. Oil Spills and Marine Pollution:
   • Accidental spills from offshore drilling, ocean transportation, and exploitation activities pollute coastal waters.
   • Oil spreads over water surface, affecting birds and aquatic life by clogging feathers, reducing insulation, and causing deaths.
6. Household Detergents: Contain phosphates, nitrates, ammonium compounds, and alkyl benzene sulphonate which accumulate in water and act as nutrients, leading to eutrophication and algal blooms.
7. Suspended Matter and Silt: Suspended solids reduce light penetration, inhibit photosynthesis, clog fish gills causing suffocation, and alter stream bed conditions affecting bottom fauna.