吉林西部盐碱土区土壤有机碳-无机碳转移通量和转化机制研究

Western Jilin Province is one of the three concentrated regions of saline-alkaline soil in the world, which belongs to the Northeast China transect of global change research and is an important study area of global climate change and carbon cycle. The study takes cultivated soil as an example and adopts 3S technology, field monitoring, experimental simulation, molecular biology, isotope technique and model simulation methods. Firstly, DNDC model and area method are used to estimate the storage of soil organic carbon(SOC) and soil inorganic carbon(SIC) and the spatial distribution law is revealed. Then, the transfer content is analyzed through isotope technique and various models. Meanwhile, physical protection and chemical transformation and stabilizing effects on SOC of physical and chemical properties such as soil texture, aggregates, organic matter under saline-alkaline stress are analyzed. Furthermore, the response model of carbon and soil enzymes is built, microbial community structure is revealed, and the role of microorganism on SOC-SIC conversion process is simulated. Finally, the conversion mode of SOC-SIC in saline-alkaline soil region is built to estimate the contribution of carbon sequestration of carbon conversion process to soil carbon and CO2 in the atmosphere. The feature of the study is to include SIC into storage estimation of soil carbon and to explore the carbon conversion mechanism from physical, chemical and biological aspects. Therefore, the result will have great theoretical significance and application value for accurately estimating soil carbon storage, evaluating the contribution for global change caused by inorganic carbon pool, perfecting the technique system of carbon cycle study in northern terrestrial ecosystem and mitigating and adapting global climate change.

吉林西部为世界三大盐碱地集中分布区，位于全球变化研究中国东北样带内，是全球气候变化和碳循环研究的重要区。本研究拟以耕作土为对象，采用3S技术、监测与实验模拟、分子生物学、同位素技术和环境模型模拟等，利用DNDC模型和面积法估算土壤有机碳（SOC）和无机碳（SIC）储量，揭示空间分布规律，计算转移通量；分析盐碱胁迫下土壤质地、团聚体、有机质等对SOC物理保护作用、化学转化与稳定作用；建立碳与土壤酶的响应模型，揭秘土壤微生物群落黑箱，模拟微生物在SOC-SIC转化过程的作用；构建盐碱土区SOC-SIC的转化模式，评估碳转化过程对土壤碳库以及大气CO2的碳汇贡献。将SIC纳入土壤碳库储量估算，从物理化学和生物多方面深入研究碳转化机制是其特色。成果对于准确估算土壤碳储量，评估无机碳库对全球变化的贡献，完善北方陆地生态系统碳循环研究的技术方法体系，减缓与适应全球气候变化等有重要的理论意义和应用价值。

吉林西部为世界三大盐碱地集中分布区，是全球气候变化和碳循环的重要研究区。本项目采用3S技术、野外监测与实验模拟、分子生物学、同位素技术和模型模拟等，以盐碱土区的土壤有机碳与无机碳转移机制为主要研究目标，重点开展了有机碳和无机碳含量分布特征，有机碳和无机碳转化机制和转移能量，包括物理、化学和生物因素在内的影响其转化的综合影响机制，构建了水田和旱田的有机碳变化的响应模型。研究表明，土壤有机碳（SOC）呈现表层富集现象，其中土壤活性有机碳（DOC、ASOC、LFOC、MBC）和惰性有机碳（ROC）均随土壤深度的增加而降低，富集于土壤表层；耕作前后对比，SOC、MBC、ASOC、LFOC和ROC含量均有所增加，耕作有益于SOC的固定。盐碱水田和旱田的SOC和SIC呈显著的负相关关系（P<0.05），随土地整理开发，大规模的种植促进了研究区土壤碳的累积，在全球碳循环中，盐碱农田土壤是重要的碳汇。借助稳定同位素技术研究发现旱地土壤植物源SOC含量较低，水田土壤植物源SOC含量占比较高；SIC主要为次生碳酸盐，旱田表层土壤次生碳酸盐较多，而水田底层土壤含量较高，在植物或土壤微生物的协同作用下，SOC矿化产生CO2,增加了土壤次生碳酸盐的含量。以玉米为主要作物的盐碱旱田的表层土壤有机碳的δ13C值变化不大，即对植物源碳的固定效果较差，不利于长期固碳，相对而言，水稻的种植有利于长期固碳。在作物不同生长时期，SOC含量与土壤蔗糖酶、淀粉酶、过氧化氢酶、β-葡萄糖苷酶活性，及细菌、真菌、放线菌数量呈正相关关系，与SIC含量显著负相关，土壤盐碱程度、腐殖质含量、土壤酶活性和微生物作用是影响SOC-SIC周转的重要因素。研究成果揭示了苏打盐碱土区土壤有机碳与无机碳的转化机制和影响因素，对于科学评估苏打盐碱土区无机碳库对全球变化的贡献、构建农田生态系统减缓与适应全球气候变化的应对体系有指导意义。