IDENTIFICATION OF THE POLLUTING SOURCES OF THE VAVUNIY A TANK AND THEIR EFFECTS TO PROVIDE SUITABLE MANAGEMENT SUGGESTIONS

Abstract

One and only tank in the heart of the Vavuniya town is Vavuniya tank. Thequality of water in the tank is degraded due to various anthropogenicactivities. These activities include rapid urbanization and agriculturalpractices. The objectives of the study were to identify the sources of pollutionto the tank and significance of the impacts from pollution and proposingmeasures to prevent further degradations of the tank.

Six sampling locations were selected. The samples were collected at adistance about 2-3 meters away from the edge of the water spread area of thetank and to a depth of 30-45cm for 3 days. Electric conductance (EC), pHand salinity were measured by portable meters and standard methods wereused in the determination of CI- (Chloride), N03- (Nitrate), DissolvedOxygen (DO), Biochemical Oxygen Demand (BOD), Total Dissolved Solid(TDS) and Total Suspended Solid (TSS). The obtained values were comparedwith Sri Lankan Surface Water Tolerance Limits. Several pollution sourceswere also identified.

The results of the analysis elucidate that cr and pH were within the tolerancelimit in all these locations but the TSS and N03- were very high. Salinity andEC were very high at Waste Water Drainage site, College of Education siteand close to the Rice Mill site. BOD and DO values were found to be high atthe Waste Water Drainage site and close to the Rice mill site. Pollutionsources identified during the study showed high number of Eichomia,Parthinium and Salvinia, improper solid wastes, oil, grease and wastewater.Other than these some encroachers are in the tank bed.