高潜水位煤矿区复垦土壤有机碳演变特征及转化机理研究

The mining area with high groundwater level is mainly located in 5 provinces on the mid-eastern plain of China. These areas are important producing places of cereal, cotton and oil, and they are primary coal-producing places as well. According to the characteristics of multiple coal seams, deep and waterlogged subsidence, and serious farmland destruction in these areas, we carry on a research on evolution characteristics and switching mechanism of soil organic carbon in the coal mining subsidence areas after land reclamation. This research mainly studies in the following three aspects: Firstly, we deploy laboratory analysis and remote sensing retrieval interpretation to analyze the distribution characteristics of different soil organic carbon and its components . We screen out the sensitive components of organic carbon, use stable isotope technique to analyze the turnover rate of soil organic carbon, and eventually reveal an evolution law of soil organic carbon in land reclamation area. Secondly, we study the variation characteristics of environmental factors in different reclamation modes, the factors we study include soil compaction, soil bulk density, soil porosity, soil structure, soil temperature, etc. We illustrate the variation law of soil microorganism features such as their community, activities, and enzyme activities under the change of soil environmental factors. We build a relational model on (1) soil environmental factors, (2) soil microorganism structure, activities, and enzyme activities, and (3) soil organic carbon and its components, in order to reveal the evolution mechanism of soil organic carbon in land reclamation area. Thirdly, we find out the sources where the soil organic carbon in land reclamation area comes from by utilizing the stable isotope technique. We analyze the mineralization rate of soil organic carbon, and reveal the time effect of soil organic carbon in land reclamation area. In addition, we analyze the changes in molecular structure of soil organic carbon in land reclamation area by x-ray diffraction technique, and build model on the restoration years of soil organic carbon in land reclamation area.

高潜水位煤矿区主要分布于我国河北省、河南省、山东省、安徽省和江苏省等5省，该区域是我国重要的粮棉油产地，同时也是我国主要的煤矿资源地。针对该区域多煤层、塌陷深且积水、破坏耕地严重的特点，开展该区域采煤塌陷复垦后土壤有机碳的演变特征及转化机理研究。该研究利用实验室分析及遥感反演方法查明不同复垦方式、不同利用类型和不同复垦年限的土壤有机碳及组分的分布特征，筛选出有机碳的敏感组分，采用稳定同位素技术分析复垦土壤有机碳周转速率，最终揭示复垦土壤有机碳演变规律；探讨不同复垦方式土壤压实度、容重、孔隙度、结构、温度等环境因子的变异特征，阐明在土壤环境因子变化条件下的土壤微生物群落、活性及酶活性的变化规律，构建土壤环境因子—微生物结构、活性及酶活性—有机碳及组分关系模型，揭示复垦土壤有机碳转化机理；利用稳定同位素技术查明复垦土壤有机碳的来源，分析土壤有机碳的矿化速率，揭示复垦土壤有机碳的时间效应。

本项目针对高潜水位煤矿区复垦土壤有机碳演变特征及转化机理研究取得丰硕成果。在矿区土壤有机碳空间分布方面，本项目针对高潜水位煤矿区不同复垦方式土地，探讨不同复垦方式的土壤有机碳及组分的变化特征；结合变化特征筛选出对土壤复垦比较敏感的土壤有机碳组分；探讨不同复垦方式土壤有机碳稳定同位素比率（δ13C）时空分布特征，探讨不同复垦方式对复垦土壤的有机碳及组分的影响，进而揭示其演变特征，筛选合适的复垦方式，为矿区塌陷地治理提供技术支撑。根据土壤有机碳的光谱特征建立高光谱估测模型，实现土壤有机碳含量的准确估测、研究区土壤有机碳含量的空间分布反演乃至动态监测，为土地复垦以及农业施肥和土地利用提供参考；.在复垦土壤有机碳演变机理方面，本项目通过模拟实验和样地采样数据，分析不同复垦方式土壤有机碳矿化速率及有机碳组分的演变特征；利用高通量测序技术测定土壤微生物数量、活性及酶活性，构建土壤环境因子-微生物、酶活性-土壤有机碳关联模型，探讨土壤总有机碳及其组分在微生物作用下的转化规律，揭示复垦土壤有机碳演变的机理。不同复垦方式会不同程度影响研究区复垦土壤质量水平的提高，加强高浅水位采煤塌陷区不同充填复垦对土壤理化性质、土壤有机碳及组分、土壤细菌群落及土壤重金属等特性的综合影响研究具有一定的科学价值，对高潜水位矿区复垦方式的选择提供一定指导意义；.在复垦土壤有机碳时间效应及恢复时间方面，本项目分别选取塌陷-复垦0年-复垦3年-正常耕地和充填复垦区-挖深垫浅区-区域平调区的土壤作为研究对象，分析出土壤有机碳完整复垦周期演变特征和恢复速率，比较不同复垦方式对有机碳恢复速率的影响，从而为寻找最优的复垦方式提供数据支撑。