地质封存二氧化碳泄漏对农田生态系统生产力的影响模拟研究—以北方地区玉米为例

Carbon capture and storage (CCS) is key strategic technology of global carbon mitigation, however, the CCS projects face enormous challenges in security and other aspects. Especially, stored carbon dioxideleakage causing serious threat to surface ecosystem is major obstacle to CCS development. Before this study, we finished a manual control device on an agricultural ecological system threatened by leakage form carbon dioxide storage sites, to simulate the scenarios of geologically stored carbon dioxide leaking from underground to ground. And we have observed and recorded several important parameters of an agricultural ecological system (AES) are changed. The results showed that maize growth was negatively affected under different carbon dioxide Leakage amounts. In general, maize grew worse when carbon dioxide leaking flux increased. For example, seeding of maize was severely hampered, both plant height and leaf amount decreased with increasing of carbon dioxide Leaking flux. Biomass for both underground and above ground with carbon dioxide leaking was significantly less than that of control, photosynthesis of maize was affected, and soil pH value dropped. As a result,the tolerable threshold valve of carbon dioxide leakage form geologically stored sites is 500-2000g. But impacts of stored carbon dioxide leakage on ecosystem production is still not uniform understand. The main impacts was attributed to soil carbon dioxide concentration, however, the carbon dioxide in air will contribute to plant growth. Therefore, the stored carbon dioxide leakage affect ecosystem production include at least two processes: soil carbon dioxide concentration “inhibition effect” and air carbon dioxide concentration “Fertilization effect”. This research will integrate carbon dioxide leakage simulation platform and simulation methods, systematically simulate the process of stored carbon dioxide leakage`s impacts on maize production, build multi-scales stored carbon dioxide leakage impact simulation model and methodology, assess agro-ecosystem production impacts of soil acidification and replacement effect caused by carbon dioxide concentration, identify the contribution between inhibition of soil carbon dioxide concentration and fertilization effect of atmospheric carbon dioxide concentration, comprehensive assess the impacts of stored carbon dioxide leakage on agro-ecosystem production, provide environmental assessment criteria for implying and planning CCS projects and basis for decision making of governments and relative institutes.

碳捕集与封存（CCS）是全球碳减排的重要战略性技术，但CCS工程在环境安全性等方面面临巨大挑战，特别是封存二氧化碳泄漏对地表生态系统的严重威胁是CCS工程的重要障碍之一。本研究以受封存二氧化碳泄漏影响的农田生态系统生产力为研究对象，通过构建整合土壤－植物－大气的封存二氧化碳泄漏模拟平台，开展泄漏导致的土壤和大气二氧化碳浓度增加对玉米生物量和产量的影响实验。通过控制二氧化碳泄漏途径形成“土壤－大气二氧化碳浓度升高”与“土壤二氧化碳浓度升高”两种影响情景，探讨土壤二氧化碳浓度升高对玉米产量的“抑制作用”与大气二氧化碳浓度升高的“肥效作用”的贡献率，并结合大田土壤二氧化碳浅层释放试验，综合评估封存二氧化碳泄漏对玉米产量的影响，全面揭示封存二氧化碳泄漏对农田生态系统生产力影响的机理，为正在实施和规划中的CCS示范项目提供环境影响评估的定量标准，为政府和相关机构提供决策依据。

地质封存CO2是全球GHG减排的重要战略方向之一。本研究针对地质封存CO2泄漏对植物的影响开展评估，建立土壤－植被－大气整合封存CO2泄漏模拟平台，实现“土壤-大气CO2浓度升高”和“土壤CO2浓度升高”两种关键泄漏情景的物理过程和高精度控制，为检测土壤CO2浓度升高对玉米产量的“抑制作用”与大气CO2浓度升高的“肥效作用”的贡献提供重要基础。通过对玉米生理指标、土壤理化性质对土壤/大气CO2浓度变化响应的系统观测与统计分析，构建适用地质封存CO2泄漏对生态系统综合影响的模拟试验和评估方法体系；揭示封存CO2泄漏导致的土壤CO2浓度升高对玉米产量的“抑制作用”与大气CO2浓度升高的“肥效作用”的贡献率。研究发现：1）在地质封存CO2高泄漏情景下，土壤CO2浓度升高对玉米株高、干物质的量、产量的“抑制作用”可以达到10.41%，32.58%、30.62%，对地表植物的生理形态具有显著的负面影响。2）地质封存CO2泄漏导致大气中CO2浓度升高，大气CO2浓度升高的“肥效作用”会抵消土壤CO2浓度升高导致的部分“抑制作用”，使得玉米株高、干物质的量、产量下降幅度减少2.67%、3.15%、3.98%。3）地质封存CO2泄漏对植物的“抑制作用”和“肥效作用”是学界讨论CCS环境风险的重要议题，本项目通过实验提出“抑制作用”和“肥效作用”的定量评估结果，为未来CCS环境风险的评估提供重要参考。