Geochemical Characteristics of Six Tank Thaullaofthirappane and Mahakanumullatank Cascades in Dry Zone of Sri Lanka
The specific objective of this study is to monitor geochemical composition and spatial distribution of major plant nutrients and heavy metals in thaulla areas of both Mahakanumulla and Thirappane cascades in dry zone of Sri Lanka. In sediment samples total N, available P and S, exchangeable K, Ca and Mg, total Zn, Mn, Cu and Cd were measured using standards procedures. The data were analyzed statistically using SAS software package. Spatial distribution maps were prepared based on the results using Arc GIS 9.3 version. This study reveals that average N content inthaulla is relatively high and almost double the average N values of paddy soils of the commanding areas. In both cascades, Cd content in six thaullashowed much higher values than the Cd values in all paddy soils. All other elements viz: Cu, Zn and Mn values in thaulla were similar with the value obtained from paddy fields of commanding areas and were well below the permissible levels except Cd. Spatial distribution of N, P, K and Cd showed similar pattern and high concentration could be observed in the areas closed to paddy fields. Therefore it can be concluded that the geochemical composition of thaulla and spatial distribution of elements depend on cultivation type above the thaulla and anthropogenic activities.
Keywords - Geo-chemical composition, sediments, tank cascade