植物对地质封存二氧化碳泄漏的耐受机理研究

More than 12 carbon capture and storage (CCS) demonstration projects have been established in recent years in China. Obviously, CCS is seen as an emission reduction option with great potential in China because it could support China's ongoing use of coal while also controlling greenhouse gas emissions and reaching an emissions peak in 2030. Preliminary estimates show that carbon dioxide storage capacity is in the hundreds of billions of tons in China. However, the possibility of leakage from reservoirs needs to be considered, as do any subsequent effects on the environment. Then, the spatial sizes of CCS projects are up to tens to hundreds of square kilometers. It is impossible to monitor stored carbon dioxide leakage by in situ soil carbon dioxide flux sampling. Therefore, the response of plant to leaked carbon dioxide from CCS is one of the most feasible monitoring index..The tolerance of plants to elevated carbon dioxide concentration of shallow soil was key point to determine the sensitivity of bio-indicators for detecting leakage from stored carbon dioxide. However, relatively little is known about the range of plant species tolerant to carbon dioxide. This study will take plant tolerance to stored carbon dioxide leakage as the research object, employed carbon dioxide leakage simulation platform with controlled carbon dioxide concentration in soil, and to assess the tolerance of crops (maize, wheat, alfalfa, soybean, cotton, and millet) to leaked carbon dioxide, by using improved tolerance index method. The design of our experiment provided comparable and controllable environment, which is suitable for testing of the plants. The specific objective is to develop a new index (the leaking carbon dioxide tolerance index: LCTI) for plant tolerance assessment that could be used for bio-indicator selection. The LCTI will be estimated by the extent of downward shift from the baseline, with observational indicator of the control treatment as baseline. The results of assessment by using LCTI will be used to screen highly sensitive indicator plant for carbon dioxide leakage. .Meanwhile, the characteristics of plant adaptation on morphological structure and physiological metabolism to soil carbon dioxide/oxygen displace stress, especially in the change of the amount of axillary root, formation and development of root aerenchyma, activity of antioxidant enzymes, with acid-tolerance characteristic, will reveal the tolerant mechanism of plant to stored carbon dioxide leakage. It will provide reference for implying and planning CCS projects to choose indicator plant and basis for decision making of governments and relative institutes.

碳捕集与封存技术（CCS）对2030年中国温室气体排放达到峰值具有重要意义。但地质封存二氧化碳泄漏会威胁地表生态系统安全，且工业级CCS项目空间规模巨大，难以采用土壤通量测量的方式监测封存二氧化碳泄漏，植物对封存二氧化碳泄漏的响应就成为最可行的监测指标之一。本研究以植物对封存二氧化碳泄漏的耐受能力为研究对象，通过土壤二氧化碳浓度可控的泄漏模拟平台，运用改进的耐受指数方法，对北方地质封存区典型作物玉米、小麦、苜蓿、大豆、棉花、谷子对封存二氧化碳泄漏的耐受能力进行评估，筛选出可大面积种植的二氧化碳泄漏指示作物；并系统观测土壤二氧化碳/氧气置换胁迫下作物形态结构、生理代谢方面的耐受表征，特别是不定根数量、根部通气组织形成与发育、抗氧化酶活性等发生的变化，结合作物耐酸性等特征，揭示植物对封存二氧化碳泄漏的耐受机理，为正在实施和规划中的CCS项目选择二氧化碳泄漏指示植物提供定量参考和决策依据。

碳捕集与封存技术（Carbon Capture and Storage, CCS）将对全球减排温室气体发挥战略性作用，特别是对中国这样以煤为主的温室气体排放大国具有重要的意义。初步估计表明中国潜在的CO2捕集与封存能力在千亿吨规模，CCS将为我国2030年温室气体排放达到峰值做出重要贡献。但封存CO2存在泄露风险，利用植物的耐受性可用于指示作物筛选。本项目以植物对封存二氧化碳泄漏的耐受能力为研究对象，对北方地质封存区典型作物玉米、三叶草、苜蓿 、大豆、谷子、大刍草对封存二氧化碳泄漏的耐受能力进行评估。建立土壤CO2浓度可控的泄漏模拟平台，实现CO2泄漏胁迫过程，并实现对实验对象响应的全过程观测。通过三年的研究工作，系统评估玉米、三叶草、苜蓿 、大豆、谷子、大刍草等北方代表性作物对CO2泄漏胁迫的响应，识别出代表性作物对CO2泄漏耐受能力的差异。通过对实验对象响应的全过程观测。完成了对玉米、三叶草、苜蓿 、大豆、谷子、大刍草等6种代表性作物的耐受性实验，通过不同作物、不同处理的对比分析，识别出作物对CO2泄漏耐受能力的差异。发展出适用于评估作物对泄漏CO2耐受能力的指数LCTI，为定量评估不同作物对CO2泄漏的耐受能力提供可靠方法。构建了适用于作物的泄漏CO2耐受指数（Leaking CO2 Tolerance Index, LCTI）方法，可有判别玉米、三叶草、苜蓿和大刍草等作物对泄漏CO2耐受水平。提供了选择泄漏CO2的指示植物的方法。分析不同作物对CO2泄漏耐受能力差异的影响因素。发现地质封存CO2泄漏速度差异、植物毛根直径等对植物耐受CO2泄漏能力的影响，为揭示植物对CO2泄漏耐受能力的机理提供科学依据。在地质封存CO2快速泄漏模式下，玉米的叶片数、根长和光合作用等生理形态指标均显著低于慢带泄露模式。发现在CO2泄漏条件下植物毛根直径显著大于对照处理情景，说明毛根对CO2泄漏具有显著响应，间接导致作物营养、水分受到抑制。本项目研究成果对筛选高敏感性的指示作物，建立CCS项目长期环境安全监测体系，制定CCS项目的监测方案与标准，确保我国CCS项目的生态安全性具有重要的科学参考价值。