Q.What is BOD?

Human activity has altered ecosystems at scales from local water bodies to the global atmosphere, and several distinct forms of pollution and conservation response are recognised.

Ozone depletion results chiefly from industrial chemicals such as chlorofluorocarbons (CFCs) rising into the stratosphere and catalytically breaking down the ozone layer that normally absorbs harmful UV radiation, increasing UV exposure at the surface and associated health/ecological risks. Eutrophication is the excessive nutrient enrichment of a water body (mainly from fertiliser runoff, detergents and untreated sewage), triggering algal blooms whose subsequent decomposition depletes dissolved oxygen and suffocates aquatic life. The greenhouse effect — the natural trapping of outgoing heat by atmospheric gases like carbon dioxide and methane — is intensified by human fossil-fuel burning and deforestation, driving global warming and its consequences (melting ice, rising sea levels, shifting climate patterns).

Noise pollution from traffic, industry and construction disrupts animal communication and breeding behaviour besides causing human hearing damage and stress. Radioactive waste, from nuclear power and medical/military use of radioisotopes, remains hazardous for very long periods and requires specialised long-term containment. E-waste — discarded electronics — contains recoverable materials alongside hazardous heavy metals and toxic flame retardants that can leach into soil and water if improperly dumped or informally recycled. …