二氧化碳泄漏对海水化学性质影响的模拟研究OA北大核心

Carbon capture,utilization,and storage(CCUS)is an important strategy for addressing climate change and ocean acidification.To assess the risks of CO2 leakage in the marine environment for the CCUS projects in the Bozhong and Xijiang Oilfields,China,seawater samples were collected from the Bohai Sea and South China Sea.Monitoring experiments were conducted under different CO2 leakage rates and temperature conditions to examine the responses of pH,dissolved oxygen(DO),and the CO2-carbonate buffer system composition to CO2 leakage in seawaters.The results revealed that:(1)pH and DO exponentially decreased with CO2 leakage over time under the CO2 leakage rates of 10-100 mL/min and temperatures of 5℃-25℃.When the experimental systems reached equi-librium,pH dropped to 4.04 in the South China Sea group and 4.92 in the Bohai Sea group.As temperature rose,the rate of change in pH increased,whereas that in DO decreased.Moreover,pH positively responded to CO2 leakage,whereas DO negatively responded.(2)After reaching equilibrium,the CO2 carbonate system was predominantly composed of carbonic acid,accounting for 98%and 91%of the total components in the experimental groups of South China sea and Bohai Sea,respectively.Its composition was independent of the CO2 leakage rate but was re-lated to the original composition of seawater and temperature and salinity conditions in the experimental seawater groups.Meanwhile,the partial pressure of CO2 in the system increased,and total alkalinity decreased.(3)DOC concentrations increased by 8.0%-60.5%after the CO2 leakages,whereas the average bacterial abundance de-creased by 6%-22%.This suggests that CO2 leakage led to extreme changes in the chemical environment in sea-waters,such as the acidity and alkalinity,composition of the seawater buffer system and dissolved gas balance,which would further affect the DOC distribution in the carbon cycle and bacterial abundance in low trophic level.