The impact of human activities on CO2 intake by carbonate weathering a case study of Conglin karst ridge-trough at Fuling Town, Chongqing, China

The chemical weathering can consume atmosphere/soil CO₂. Human activities such as pollution, fertilization and acid precipitation have exerted a large impact on CO₂ intake by carbonate weathering. Thus, based on the analysis on chemical component change of the karst groundwater in the karst ridge watershed of Conglin Village, Fuling District of Chongqing City, the influence of human activities such as fertilization, sewage discharges from mustard tuber processing, breeding industry and acid rain precipitation on carbonate weathering and CO₂ intake in 1980, 2003 and 2006 was studied. The results showed that CO₂ intake by carbonate rock declined with year. Because H⁺ derived from acid sewage discharge, fertilization and acid precipitation reacted with carbonate rock when mustard tuber production and swine breeding were developed fleetly after 2000 as well as the burning amount of high-sulfur coal augmented persistently, which led to the increase of (Ca²⁺+Mg²⁺)/HCO₃^-. The difference on charge between Ca²⁺+Mg²⁺ and HCO₃^- was balanced by NO₃^-+SO₄^2-. The control on pollution and acid rain, especially the pre-neutralization of acid waste water, would rejuvenate the atmospheric CO₂ intake strength of carbonate weathering besides the protection of water and soil environment.