黄河三角洲滨海湿地沉积物有机碳库分配格局与动态变化研究

Coastal wetland is located at a critical interface between the terrestrial and marine environments, while soil organic carbon (SOC) pool is crucial to the carbon budget. Carbon fluxes in the wetland are largely controlled by the highly bio-reactive labile pools, while long-term storages of carbon are determined by the recalcitrant fractions. To date, knowledge of labile organic carbon pools and recalcitrant organic carbon pools in coastal wetland soils are still scarce, moreover, comprehensive research data related to the microbial community remain extremely limited. Based on the sensitivity of source-sink pattern for blue carbon under the global change, this project is aimed at the systematical study of labile organic carbon pool in coastal wetland of the Yellow River delta. In this study, labile and recalcitrant organic carbon pool will be characterization by multiple indexes, to clarify the spatio-temporal variation characteristics of organic carbon pool pattern. Comprehensive multidisciplinary methods will be used to associate the geochemical characteristics of the labile organic carbon and microbial community diversity, and then reveal the coupling relation between the organic carbon and the microorganisms in the coastal wetland. More intensive information is expected to be obtained for further study of coastal wetland carbon cycle. This research would provide essential basis and distinctive ideas to clarify the evolution of organic carbon pools in coastal wetland soils and its feedback mechanism under the context of global change.

滨海湿地处于海-陆相互作用的敏感地带，沉积物有机碳库是其碳收支的核心。活性有机碳作为气候变化和基质环境变化的敏感指标，也是反映滨海湿地碳库动态的重要指示因子，稳定有机碳则控制着沉积碳库的长期固存。而目前对于滨海湿地沉积物碳库分配格局的研究十分稀少，更缺乏与微生物过程相关联的综合研究资料。基于滨海湿地蓝碳的源-汇格局对于全球变化的敏感性和指示意义，本项目拟针对黄河三角洲滨海湿地不同生境下沉积物有机碳库进行系统研究，对不同生境下沉积物中多组分有机碳进行表征，并分析各活性有机碳指标之间的关系，明确不同生境下活性有机碳库与稳定有机碳库的分布格局与动态变化；综合运用多学科交叉手段，耦合活性有机碳库与沉积物中微生物群落多样性特征，以获得关于沉积物有机碳转化机制的重要信息，诠释滨海湿地沉积物中多组分碳过程与碳库格局，为明晰滨海湿地沉积碳库在全球变化背景下的演变特征及其反馈作用奠定基础。

滨海湿地处于海-陆相互作用的敏感地带，沉积物有机碳库是其碳收支的核心。活性有机碳作为气候变化和基质环境变化的敏感指标，也是反映滨海湿地碳库动态的重要指示因子，稳定有机碳则控制着沉积碳库的长期固存。本项目对黄河三角洲滨海湿地不同生境下沉积物有机碳库进行了系统研究，对不同生境下沉积物中多组分有机碳进行表征，分析沉积物中微生物多样性，明确不同生境下活性有机碳库与稳定有机碳库的分布格局与动态变化，以获得关于沉积物有机碳转化机制的重要信息，诠释滨海湿地沉积物中多组分碳过程。本项目获取了沉积物中碳的储存与矿化特征，解析了滨海湿地沉积物中有机碳库分配格局，基于滨海湿地沉积环境和层序特征，对滨海湿地的碳贮存与分解特征进行考察，获取了沉积物中有机碳氮含量及稳定同位素特征。在一定的深度内，芦苇覆盖下沉积物的难降解有机碳为19.0 kg m-2，是相同水文条件下碱蓬覆盖沉积物和光滩沉积物的2倍和6倍。通过解析滨海湿地沉积物碳库格局与碳埋藏能力，明确规律性的淹水使沉积物处于厌氧环境，导致有机质矿化分解速率较低，并使得有机碳得到更多的保存。植被是控制碳埋藏能力大小的关键因素，而水文条件则是决定有机碳埋藏效率的关键因素。在此基础上，探索滨海湿地碳的沉积与埋藏能力的提升策略，可为我国滨海湿地碳库动态监测提供科学依据，为预测滨海湿地碳平衡对气候变化的响应和反馈提供理论基础，为进一步阐明我国滨海湿地碳库在全球变化背景下的源汇功能转化与滨海湿地修复提供新的思路。