Water geochemistry of the Chaohu Lake Basin rivers, China: Chemical weathering and anthropogenic inputs

As one of the five largest freshwater lakes in China, the Chaohu Lake is polluted by many kinds of pollutants. Chemical and Sr isotopic compositions of river waters in the Zhegao River sub-catchment have been determined with the main purpose of understanding the contribution of chemical weathering and anthropogenic inputs to solutes. The major ion compositions of the river waters are characterized by the dominance of Ca2+ and HCO3-, followed by Mg2+ and SO42-. The chemical and Sr isotopic analyses indicate that three major reservoirs (carbonate, silicate and human activities) contribute to the dissolved load. The calculated results show that the dissolved load is dominated by carbonate weathering. The contribution of the anthropogenic inputs is estimated to be from 1.64% to 31.8%, with an average of 15.6%, demonstrating the strong impacts of human activities on water chemistry. The total chemical denudation flux of the Zhegao sub-catchment is about 127.7 ton km (2) a (1), with carbonate and silicate weathering rates of 97.5 ton km (2) a (1) and 30.2 ton km (2) a (1), respectively. (C) 2011 Elsevier Ltd. All rights reserved.