黄河三角洲潜在碳封存区域二氧化碳环境背景基线特征分析OACSTPCD

The large-scale sequestration of CO2 may result in leakage,which could intrude into the shallow sub-surface and cause environmental impacts.Due to the complex changes of natural processes,accurately determi-ning baseline values and distributions is crucial for monitoring and controlling near-surface leakage.This study utilized portable devices along scheduled path to conduct mobile and field monitoring and sampling laboratory test,and monitored and analyzed atmospheric and soil gas components and CO2 concentrations at potential sequestration sites in Yellow River Delta to determine baseline values and distributions.The results indicate that:①in the mo-nitoring maps of three different layers,CO2 concentration data from the portable monitoring method are consistent with the continuous monitoring data from the fixed monitoring points,indicating the periodic fluctuation character-istics of the monitored CO2 concentration.Additionally,the statistically significant relationship between δ13 CCO2 and CO2 and O2 content confirms the reliability of the portable monitoring method.② Two environmental back-ground baseline values are established.The first is δ13 CCO2 and δ13 COC baseline,with the soil δ13 CCO2 isotope val-ues of-14.35‰～-20.95‰,atmospheric δ13 CCO2 values of-16.92‰～-19.89‰,and soil δ13 COC values of-20.59‰～-24.79‰.These values revealed the range of carbon isotope values produced by biological activity in temperate climates.The second is atmospheric and soil CO2 concentration baseline,with the atmospheric CO2 concentration of 219.20～416.4 ppm,soil CO2 concentrations at 30 cm depth of 1 002.793～14 808.13 ppm,and soil CO2 concentrations at 50 cm depth of 1 497.26～19 658.59 ppm.The environmental CO2 concentration and isotope baseline of shallow surface in potential carbon sequestration sites of Yellow River Delta were confirmed in this research,providing reference benchmarks and monitoring scheme recommendations for future surface moni-toring after large-scale CO2 sequestration.