1976年以来黄河三角洲湿地沉积有机碳汇稳定性：盐度和地貌联合制约

河口三角洲湿地因其较高的固碳效率对减缓全球气候变暖发挥着重要的作用，但目前对其碳汇稳定性缺乏清晰认知。黄河三角洲湿地是一个具有高沉积性和快速演化性特征的巨大沉积有机碳汇体，开展其碳汇能力及稳定性机制研究对深入认识河口湿地生态系统碳循环过程有着重要意义。本申请拟以在1976年黄河改道清水沟流路后新形成的三角洲湿地上获取的长柱样、表层样和植物样为研究对象，将现代遥感技术与历史地理学和沉积地质学综合分析方法融合，结合国际先进的rSETs监测系统，建立沉积年代可靠、分辨率高的时间模式；引入生物标志物GDGTs，建立三端元模型，定量计算碳源贡献，在此基础上揭示不同来源活性和惰性有机碳汇能力及演变规律。通过对淡水、半咸水、盐沼环境沉积碳汇体对比研究，阐述盐度梯度上有机碳输入组成变化，阐明地貌演替对活性有机碳保存效率的影响，探讨碳汇稳定性的制约机制，其研究成果将对准确估算区域蓝碳平衡提供重要参考。

Estuarine delta wetlands play an important role in mitigating global warming due to their high carbon sequestration efficiency, but the stability of their carbon sinks is not clearly understood. The Yellow River delta wetland is a large sedimentary organic carbon sink with high sedimentation and rapid evolution. The research on its carbon sink capacity and stability mechanism is of great significance to the understanding of the carbon cycle process of estuarine wetland ecosystem. In this proposal, core sediment samples, surface sediment samples and plant samples obtained from the newly formed delta wetlands when Yellow river shifted to Qingshuigou lower reach in 1976 are regarded as the research object. Based on modern remote sensing, comprehensive analysis of historical geography and sedimentary geology and the international advanced rSETs monitoring system, a reliable and high resolution sedimentary chronological model will be established. By joining the biomarker GDGTs, a three-terminal meta-model will be established to quantitatively calculate the carbon source contribution. On this basis, the fixation capacity of labile organic carbon and Recalcitrant organic carbon will be revealed. On this basis, the activity of different sources and the capacity of inert organic carbon sink and its evolution law were revealed. Through the comparative study of sedimentary carbon sinks in fresh water, brackish and salt marsh, we will study the change of organic carbon input composition on salinity gradient, the influence of geomorphic succession on the conservation efficiency of labile organic carbon, and the decisive mechanism of carbon sink stability. The results of the study will provide an important reference for the accurate estimation of regional blue carbon balance.