Chemical Weathering and Riverine Carbonate System Driven by Human Activities in a Subtropical Karst Basin, South China

• Published in: Water
• Main Authors: Xiaoxi Lyu, Zhen Tao, Quanzhou Gao, Haixia Peng, Mei Zhou
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2018
• Subjects: karst basin; carbonate weathering; carbonate system; dissolved inorganic carbon; anthropogenic acids; the Lianjiang River; Hydraulic engineering; TC1-978; Water supply for domestic and industrial purposes; TD201-500; Carbonic acid
• Online Access: https://doi.org/10.3390/w10111524; https://doaj.org/article/4c0b01be23d74da88a2b8f328c29d952

In the context of climate change, the input of acid substances into rivers, caused by human activities in the process of industrial and agricultural development, has significantly disrupted river systems and has had a profound impact on the carbon cycle. The hydrochemical composition and which main sources of the Lianjiang River (LR), a subtropical karst river in northern Guangdong Province, South China, were analyzed in January 2018. The objective was to explicate the influence on the deficit proportion of CO 2 consumption, resulting from carbonate chemical weathering (CCW), driven by nitric acid (HNO 3 ) and sulfuric acid (H 2 SO 4 ), which is affected by exogenous acids from the industrial regions in north of the Nanling Mountains and the Pearl River Delta. The response of the riverine carbonate system to exogenous acid-related weathering was also discussed. HCO 3 − and Ca 2+ , respectively, accounted for 84.97% of the total anions and 78.71% of the total cations in the surface runoff of the LR, which was characterized as typical karst water. CCW was the most important material source of river dissolved loads in the LR, followed by human activities and silicate chemical weathering (SCW). Dissolved inorganic carbon (DIC), derived from CCW induced by carbonic acid (H 2 CO 3 ), had the largest contribution to the total amount of DIC in the LR (76.79%), and those from CCW induced by anthropogenic acids (HNO 3 and H 2 SO 4 ) and SCW contributed 13.56% and 9.64% to the total DIC, respectively. The deficit proportion of CO 2 consumption associated with CCW resulting from sulfuric acid and nitric acid (13.56%), was slightly lower than that of the Guizhou Plateau in rainy and pre-rainy seasons (15.67% and 14.17%, respectively). The deficit percentage of CO 2 uptake associated with CCW induced by sulfuric acid and nitric acid, accounted for 38.44% of the total CO 2 consumption related to natural CCW and 18.84% of the anthropogenic acids from external areas. DIC derived from CCW induced by human activities, had a ...