| 摘要: |
| 碳捕获、利用与封存(CCUS)是应对气候变化和海洋酸化的重要策略, 针对海洋环境CO2封存的泄漏风险, 该研究针对渤中油田和南海北部西江油田的CCUS应用规划, 分别采集渤海海水和南海海水, 受控模拟不同CO2泄漏速率和温度条件, 研究海水pH、溶解氧(DO)和CO2-碳酸盐缓冲体系组成的响应特征。结果表明: ①当CO2泄漏速率为10~100 mL/min, pH和DO浓度随时间延长整体呈现指数形式降低, 接近平衡时南海和渤海实验组pH分别达到4.04和4.92。温度为5~25 ℃时, pH变化率随温度升高而增大, DO浓度变化率随温度升高而降低。pH对CO2泄漏发生正向响应, DO发生负向响应。pH随压力的增大呈现指数形式的降低。②CO2泄漏达到平衡时, CO2-碳酸盐体系组成以碳酸为主, 南海和渤海实验组碳酸组分别达到98%和91%, CO2-碳酸盐体系组成与CO2泄漏速率无关, 与实验水体的原始组成和温盐条件有关; 同时, 体系CO2分压升高, 总碱度降低。③CO2泄漏使实验组溶解有机碳浓度增加了8.0%~60.5%, 细菌丰度平均降低了6%~22%。研究显示, CO2泄漏引起海水酸碱性、CO2-碳酸盐缓冲体系和溶解气体平衡等化学环境的极端变化, 进而影响了碳系统中溶解有机碳分布和低营养级生物细菌丰度。 |
| 关键词: 海洋CO2泄漏 酸碱度 CO2-碳酸盐缓冲体系 溶解有机碳 细菌 |
| DOI：10.11759/hykx20241024001 |
| 分类号:X141;P76 |
| 基金项目:中国海洋石油集团有限公司“十四五”重大科研项目CCUS专项(KJGG-2022-12-CCUS-0105) |
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| Impact of stored CO2 leakage on the chemical properties of seawater |
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MA Zhiyao1, YU Song2, LOU Qi3, ZOU Li2, LIU Tao1, LI Yanzun1
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1.China National Offshore Oil Corporation (CNOOC), Beijing 100028, China;2.Key Laboratory of Marine Environment and Ecology, Ocean University of China, Qingdao 266100, China;3.School of Environment and Geography, Qingdao University, Qingdao 266071, China
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| Abstract: |
| 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°C-25℃. When the experimental systems reached equilibrium, 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 related 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 decreased by 6%-22%. This suggests that CO2 leakage led to extreme changes in the chemical environment in seawaters, 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. |
| Key words: marine CO2 leakage acidity and alkalinity CO2 carbonate buffer system dissolved organic carbon bacteria |
