Study on the Effect of CO2 Leakage on the Basic Water Quality Index of Paddy Field Water

CO2 capture and storage (CCS) technology is an effective method to restrain the excessive growth of CO2 in the atmosphere. However, there are still risks of CO2 leakage during the implementation of CCS project, which may pose a threat to the surface environment and ecology. In this study, Longjing 31 and Longdao 18 were taken as experimental objects to simulate the leakage of geologic storage CO2 at different rates and to discuss its effects on the basic water quality indexes of paddy field water, such as DCO2, pH, DO and ORP, so as to explore the response rules of paddy field water to geologic storage CO2 leakage. The results indicated that CO2 leakage had significant long-term effects on DCO2, pH, DO and ORP of water in the paddy field, and different CO2 leakage rates had significant differences on water quality indexes in the paddy field. After the balance of all indexes, the water quality indexes of paddy field water showed obvious diurnal variations, in which DCO2 was high in the morning and evening, and low in noon, while pH, DO and ORP were opposite. According to the difference analysis of each index, it is suggested that DCO2 in paddy field water should be taken as the main index of CO2 leakage monitoring in paddy field system, and pH, DO and ORP should be used as the auxiliary indexes of CO2 leakage monitoring.