Page 4 - LN-CH-16

(a) By applying sound-absorbent materials or by muffling noise in industrial units.
(b) Delimitation of horn-free zones around hospitals and schools.
(c) Strict laws for permissible sound levels of crackers and loudspeakers should be
followed.
(d) Loudspeakers should be played up to a fixed time only.
4. Water pollution is any undesirable change in the physical, chemical or biological
properties of water that may affect the human beings and aquatic species.
(ii) The Government of India has passed the Water (Prevention and Control of Pollution) Act,
1974 to safeguard our water resources.
(ii) Sources of Water Pollution
(a) Domestic sewage includes everything that comes from residential area to common
public sewage system. A mere 0.1% impurities make domestic sewage unfit for human use.
Composition of domestic sewage
* Suspended solids, e.g. sand, silt and clay.
* Colloidal material, e.g. faecal matter, bacteria, cloth and paper fibres.
* Dissolved materials, e.g. nutrients (nitrate, ammonia, phosphate, sodium and calcium).
* It mainly contains biodegradable organic wastes, which are readily decomposed with the
help of decomposers.
(b) Industrial wastes are released by petroleum, paper manufacturing, metal • It contains
heavy metals like mercury and many organic compounds.
(iii) Effects of Water Pollution