干旱区生态环境知识资源中心

The Li isotope geochemistry of the Jinshajiang (upper reach of the Changjiang), Lancangjiang (Meckong) and the Nujiang (Salween) rivers have been studied to better understanding the weathering of continental crust. The three rivers show different water geochemistry, the Jinshajiang followed by the Lancangjiang contains much solute from dissolution of evaporites; the Jinshajiang has the highest average Li content and delta(7)Li values. The relatively low delta(7)Li values (+4.74 similar to+12.9%) of the river waters, compared to those of large rivers in the world, probably reflect less weathering intensity in this arid and cold region. The Jinshajiang water has relatively high and constant delta(7)Li values, and is considered to be affected by evaporite dissolution and the high delta(7)Li values indicating that precipitation of salt minerals might have resulted in enrichment of (7)Li in the remaining water. It is thought that H(2)SO(4) has been involved in crustal weathering in the region, especially in the Nujiang basin. (C) 2011 Elsevier Ltd. All rights reserved.