YU Chong^1,2, XU Zhifang^1,2, LIU Wenjing^1,2,3, SHI Chao^1,2, ZHANG Xuan^1,2, ZHAO Tong^1,2, JIANG Hao^1,2, ZHOU Li^1,2, ZHOU Xiaode^1,2

(Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;
2.University of Chinese Academy of Sciences, Beijing 100049, China;
3.Earth and Environmental Systems Institute and the Department of Geoscience, The Pennsylvania State University, University Park, PA 16802, UCAS)

Abstract: Chemical weathering is an important process in global carbon cycle, and the weathering of silicate rocks is a significant mechanism for regulation of atmospheric CO2 concentrations on geological time scale. In this study, we analyzed ion compositions of water in the Hanjiang River Basin, which are lithologically dominated by silicate rocks and located in the Southeast of China. We estimated the rock weathering rate and CO2 consumption flux in the Hanjiang River Basin. Besides, sulfuric acid participating rocks weathering and carbon cycle processes were identified. Results show that water chemistry in the Hanjiang River Basin is mainly controlled by chemical weathering of silicate rocks and carbonate rocks. The weathering rate of carbonate rocks is 21.7t/(km2·a) while the rate of silicate rocks is 18.9t/(km2·a). Calculations of end-member contribution indicate that 41% of the SO42- originated from precipitation. The presence of sulfuric acid increased the cationic load account for 65.9% of the total cationic load origin, and overestimated CO2 consumption rate by 61%.

Key words: rock weathering; chemical weathering rate; atmosphere CO2 consumption; Southeast of China; Hanjiang

EARTH AND ENVIRONMENT Vol.45, No.4, Tot No.318, 2017, Page 390-398