地质封存CO_2泄漏对农田生态系统的影响评估及耐受阈值

Impact assessment and tolerable threshold value of CO_2 leakage from geological storage on agro-ecosystem

碳捕获与封存(carbon capture and storage,CCS)是全球碳减排的重要战略性技术,但封存CO2泄漏对地表生态系统的严重威胁是CCS活动的重要障碍之一。该研究选择受封存CO2泄漏威胁的农田生态系统作为研究对象,通过运用人工控制手段模拟地质封存CO2泄漏到达地表的系列情景,监测农田生态系统主要指标变化,评估和确定封存CO2泄漏对农田生态系统的影响和耐受阈值。研究结果表明,不同泄漏情景下玉米均受到不同程度的不利影响,并且泄漏通量越大,影响程度越深:CO2泄漏情景下的玉米出苗受到严重阻碍,株高和叶片数随泄漏通量增大而呈逐渐减小的趋势,地上部和地下部生物量较对照情景明显减少,光合作用受到干扰,土壤pH值降低。500～2000g/(m2·d)范围内的泄漏情景为玉米对地质封存CO2泄漏的耐受阈值。

Carbon capture and storage（CCS） technology plays an important role in reducing global carbon emission.However,CCS project is facing many obstacles,particularly the leakage from carbon dioxide（CO2） storage sites severely threatens ground ecological systems.In this study,a manual control device was designed and constructed,on an agricultural ecological system threatened by leakage from CO2 storage sites,to simulate the scenarios of geologically stored CO2 leaking from underground to ground.The changes of several important parameters of an agricultural ecological system（AES） were observed and recorded so as to evaluate impacts of underground stored CO2 leaking on an AES,and then to establish the tolerable threshold value.The results showed that maize growth was negatively affected under different CO2 leakage amounts.In general,maize grew worse when CO2 leaking flux increased.For example,seedling of maize was severely hampered,both plant height and leaf amount decreased with increasing of CO2 leaking flux.Biomass for both underground and above ground with CO2 leaking was significantly less than that of control,photosynthesis of maize was affected,and soil pH value droped.As a result,the tolerable threshold value of CO2 leakage from geologically stored sites is 500-2 000 g/（m2？d）.