TAILIEUCHUNG - Surface Water Pollution by Nitrogen Fertilizers

• There is need to diversify urban-development activities within the municipality. An outward spread of these development activities and the creation of satellite towns in areas such as Olkaria, Sulmac and Sharlimar would minimise the pressure on the natural environment, land, forests, air and water resources, as well as on the capacities of socio-economic infrastructures such as sewerage and water supply facilities and roads. This will also result in a reduction of land use conflicts, which is a major cause of environmental degradation in any given urban scenario. . | Surface Water Pollution by Nitrogen Fertilizers Gregory McIsaac University of Illinois Urbana Illinois . INTRODUCTION The use of industrially manufactured nitrogen N fertilizers increased rapidly in developed countries between 1960 and 1980. This facilitated a large increase in the production of feed and food grains maize wheat and rice per unit of cultivated land but in some regions it also contributed to enrichment of surface and groundwater with various forms of nitrogen. Fertilizer however is not the only source of nitrogen that can cause contamination of surface waters. Biological nitrogen fixation mineralization of soil organic nitrogen and animal wastes can also contribute to nitrogen enrichment of water bodies. Additionally under some conditions nitrogen applied to the soil may be converted to gaseous or immobile forms of nitrogen that do not contribute to surface water contamination. Because of these various sources and transformations of nitrogen the severity of surface water contamination by nitrogen fertilizer has been difficult to precisely quantify. Existing research indicates that the amount of contamination from fertilizer varies depending on the amount of fertilizer applied and characteristics of the soils crops climate and the receiving water bodies. Problems Caused by Nitrogen Pollution of Surface Waters There are three water quality concerns associated with different forms of nitrogen. First the combined concentrations of nitrate NO32 plus nitrite NO22 in excess of can contribute to methemoglobinanemia blue baby syndrome in infants if ingested. 1 To guard against this the . Public Health Service limits nitrate plus nitrite concentration in public drinking water supplies to 10mgN L2 . Secondly unionized ammonia NH3 may be toxic to fish at concentrations as low as mg NL2 . Finally elevated total nitrogen concentrations including nitrate ammonia and organic forms in rivers can promote the process of cultural eutrophication in

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