Water-environmental Effects Induced by Discharging Geothermal Wastewater with High As Levels:A Case Study at Yangbajing in Tibet

The geothermal power plant at Yangbajing of Tibet discharges effluents containing high arsenic directly into the Zangbo River,the major surface water body which is joined by the Yangbajing River.This study is based on a simultaneous survey including river water and sediment sampling and analysis of As and focused on the effects of dilution of river water and adsorption of river bed sediments.The comprehensive attenuation coefficients of As is calculated in different sections of the Zangbo River and compared with the adsorption coefficients of the relative sediments,indicating that there is clear exponential relation between them and natural decline of arsenic in the river is exponentially strengthened by adsorption of river sediments.