Physical and chemical characteristics of ancient and recent reservoirs of Sri Lanka
Yatigammana, S. K.; Cumming, B. F.
published: Aug 1, 2016
published online: Jul 7, 2016
manuscript accepted: Jun 28, 2016
manuscript received: Apr 4, 2016
ArtNo. ESP141018803006, Price: 29.00 €
Abstract This study explores the physicochemical characteristics in 51 shallow, meso-eutropic reservoirs from Sri Lanka. These reservoirs are largely dominated by sodium chloride, reflecting the dominance of precipitation in overall water chemistry. These reservoirs range in values of specific conductance from 19 to over 1000 μS cm–1 and can be described as slightly alkaline, mesoeutrophic to eutrophic systems. The reservoirs located in five climatic regions (Arid, Dry, Intermediate, Wet, and Highland Wet zones) of Sri Lanka that vary according to patterns in precipitation, evaporation and seasonality, which are in turn, reflected in the characteristics of the regional flora and fauna. Results from this study show that the specific conductance and related variables reflect the patterns in precipitation and evapoconcentration. The highest specific conductance values are found in the Arid and Dry Zones (median values of 677 and 379 μS cm–1), and are sequentially lower in the Intermediate, Wet and Highland Wet zones (median values of 237, 196, and 65 μS cm–1, respectively). The concentration and gradient of nutrients (total phosphorus concentration ranges from 16.6 to 664 μg L–1 median = 38.7 μg L–1) is also an important variable, although not contribute in differentiating to different climatic zones. Finally, anoxia is a persistent problem in the hypolimnia of many reservoirs, a feature which is related to thermally and chemically stratified reservoirs.