NUTRIENT LEACHING FROM SEDIMENTS

Abstract

Many lakes and rivers have reached levels of eutrophication that makes them unacceptable for recreational activities and municipal and industrial water supply purposes. The eutrophic state of these inland waters is a direct result of an increase in the availability of nutrients. The increase in nutrient may be caused by wastewater discharges, urban and agricultural runoff. Such nutrient sources (referred as external sources) may be largely eliminated through modern methods of wastewater treatment or through diversion techniques. In some inland waters,there may be an appreciable in- ternal nutrient sources in the form of benthal deposits. The nutrient release from these deposits occurs as a result of a gradient in nutrient concentration between the overlying water and the nutrient in the interstitial water of the sediment. The presence of excessive levels of nutrients in the sediments of water bodies is ultimately traceable back to the external sources. However,for some situations,the problem can be separated and the effect of nutrient release on eutrophication can be dealt with as a continuous source. The impact of sediment release can be significant and result in continuing eutrophication problems even after point sources have substantially reduced. In view of the importance of phosphorus and nitrogen in the ecology of natural