NUTRIENS DYANAMICS OF SHALLOW LAKES; A CASE STUDY OF NUWARAWEWA IN ANURADHAPURA, SRI LANKA

Abstract

Lakes are considered as natural resources and in environmental literature, it is a common property resource, accessible to everyone. Therefore lakes face special pollution problems. Most notably, they serve as sink of pollution arising and from upstream as lakeside activities including industrial discharges, municipal waste and agricultural drainage. Therefore many of the lake studies are applied to measuring of water quality parameters of lakes. Nuwarawewa is a major water body in the Anuradhapura district, it has specific ecological and sociological characteristics. Therefore a preliminary survey on the some chemical and biological quality of Nuwarawewa was carried out in order to construct a baseline for further studies. Some chemical parameters (Nitrate, Phosphate, Total Dissolved Solids and pH) and biological parameters (Plankton and Biological Oxygen Demand) were measured by using standard methods. When comparing analytical results and previous records, the increase of some nutrient particularly nitrate and phosphate were observed. Biological Oxygen Demand and plankton counts were also increased in catchments (North-Bast) side sampling points. There is no sufficient evidence to categorize Nuwarawewa as highly polluted lake. However change of water quality parameters over time suggests an increasing tendency of pollution. Further disposal of waste and other pollutants may create a problematic situation in future and a proper management plan is required to control and protect the lake.