Water pollution in Nepalby Ashtha Lamsal | 22-04-2017 17:52 |
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Water pollution is any physical, chemical or biological change in water quality that have harmful effect on living organisms and makes water unsuitable for desired uses. It is the state of deviation from pure condition, whereby its normal functions and properties are affected. The level of purity required for water depends upon on its use. Water pollution is a local as well as regional level pollution. Water pollution in Nepal is majorly due to unmanaged solid wastes, factories, sewage treatment plants, runoff of chemicals into surface water from croplands, livestock, urban streets. There is little or no control in discharge of many harmful chemicals into aquatic system. Also being an agricultural country different sediments, inorganic fertilizers, manure, salts dissolved in irrigation water and pesticides which has polluted ground water too. In stagnant water, the dilution of pollutants often is less effective than in flowing water due to the presence of stratified layer that undergo little vertical mixing. As a result, lake, ponds and reservoirs are more vulnerable than streams to be contaminated by plant, nutrients, oil, pesticides and toxic substances such as lead, mercury and selenium. Earthen septic tank and landfills may also leak to cause water pollution. Different types of water pollution leads to health hazards and also problem to aquatic food webs. It reduces the concerntration of dissolved oxygen leading fish and other forms of oxygen consuming aquatic life to die. Due to the inorganic plant nutrients like sewage and runoff from agricultural field, it can cause excessive growth of algae and other aquatic plants which grow, die, decay and deplete the dissolved oxygen of water(eutrophication) and kill fish. There are different majors to control water pollution by implementing strict rules from policy level, waste water treatment process etc. We can reduce fertilizer runoff into surface water and leaching into aquifer by using slow release fertilizers and using more non steep slope lands. Reducing the need of fertilizer by alternating planting between raw crops by nitrogen fixation plants. Also it can br prevented by storing hazardous liquid above ground in tank. And banning of disposal of hazardous waste in deep wells and landfill sites.
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