Spatial and temporal dynamics of water quality in Batticaloa lagoon in Sri Lanka

Abstract

The present study was undertaken to characterise the spatial and temporal dynamics of physico-chemical parameters of the Batticaloa Lagoon in Sri Lanka during November 2012 to October 2013. Eighteen sampling locations were clustered based on their positions from the Palameenmadu bar mouth. Physico-chemical parameters like temperature, electrical conductivity (EC), total dissolved solids (TDS), pH, salinity, dissolved oxygen (DO), turbidity, nitrate, phosphate and total suspended solids (TSS) were measured 15-30 cm below the water surface. The study revealed that the water temperature of the lagoon varied between 26.1-33.6°C; EC 0.24-36.6 dS/m; TDS 0.1-18.3 ppt; pH 7.32-8.87; salinity 1.6-34 ppt; DO 3.98-11.98 mg/l; turbidity 3-41 FAU; nitrate 0.8-8.3 mg/l; phosphate 0.04-1.56 mg/l and TSS 562-6021 mg/l. High values of salinity were observed in the lagoon water near the barmouth, and during the dry months. Rainfall and the distance from sea play a major role in the variation of salinity of the lagoon. Decreasing trend in salinity was observed from the distance from barmouth to the West, North and Southern part of the lagoon. High nutrient concentration at the lagoon was observed in the locations near to the farms and cultivation areas. The water quality parameters are favourable to the production of brackish water fish and prawns during dry months. However, it contains high salt and suspended particles, thus not suitable for drinking. The results are important in understanding the pattern of variation of water quality parameters so as to assist relevant agencies to plan, protect and aid in the management of the lagoon water for different uses.