全新世以来浙江近岸泥质区低氧事件沉积记录研究

In recent ten years, the formation mechanism and historical evolution of hypoxia in estuary and continental shelf area are research hotspots of academia. The hypoxic zone along the Zhejiang coast is selected as the major research object in this study since relatively less research work related to hypoxia has been carried out. The formation mechanism and characteristics of modern hypoxia will be studied using the current data of hydrological physical parameters, surface sediment biogeochemistry and benthic foraminifera assemble. The precise chronology framework of the Holocene sedimentary record in the study area will be constructed by AMS14C and 210Pb dating methods, and sedimentary record of hypoxia event since Holocene will be reconstructed by effective hypoxic proxies. In addition, the formation and evolution processes of hypoxia event since the Holocene will be studied based on the coupling relationship between historical hypoxia and ancient environment, combined with the modern hypoxia formation mechanism. This project is scientifically significant in revealing estuary and continental–shelf environment evolution and sedimentation process in depth and studying the regional response to global change.

河口-陆架区低氧事件的形成机制及其历史演化是学术界近十多年来的研究热点。本项目拟选取以往研究程度较低的浙江近岸低氧区为研究对象，将利用现今水文物理参数、表层沉积物生物地球化学及底栖有孔虫等数据研究现代低氧形成机制及特征；运用AMS14C和210Pb测年手段建立该低氧区全新世沉积记录的精细年代格架，并利用有效的低氧事件代用指标重建全新世以来低氧事件沉积记录；通过历史时期低氧事件与古环境之间的耦合关系，结合现代低氧成因，探讨该区全新世以来低氧事件的形成及演化过程。本项目的开展对于深刻揭示河口-陆架区环境演变与沉积过程以及全球变化的区域响应具有重要的科学意义。

河口-陆架区低氧事件的形成机制及其历史演化是学术界近十多年来的研究热点。本项目选取以往研究程度较低的浙江近岸低氧区为研究对象，基于该区黏土矿物、粒度以及有机地球化学等数据对现代低氧形成机制进行深入分析探讨；运用210Pb、137Cs测年手段建立了该低氧区近百年沉积记录的年代格架。研究发现：黑潮分支流侵入浙江陆架，底层富含营养盐的水体涌升，导致该区初级生产力旺盛，有机物质下沉耗氧，叠加黑潮分支流本身就是低氧水体，最终导致浙江近岸低氧形成。该区岩心记录的元素地球化学特征表明该区低氧自1875年就已存在，且有继续恶化的趋势。本项目的开展对于深刻揭示河口-陆架区环境演变与沉积过程以及全球变化的区域响应具有重要的科学意义。