黄河沉积物环境磁学特征及其对人类活动记录的响应

The environment magnetic research of Yellow River sediment is of vital significance on deeply understanding the "Source to Sink" process of terrigenous sediments and investigating records of human activity on marginal sea sediment. This project is based on sediment samples from Yellow River basin and sediment cores from modern and abandoned estuaries. We plan to analyze the variation patterns of environment magnetic characteristics such as types, content and grain-size of magnetic minerals, and then evaluate its variation regulations and controlling factors. According to that, we further set up the magnetic provenance indicator of Yellow River sediments and discuss the contribution of branches to the main stream. Based on the magnetic characteristics data of the two cores and combined with sediment indicators such as grain size and geochemistry of element, we carry out research on the estuary environment variation and sediment process before and after the rechanneling of Yellow River. In terms of the research above, we will build indicator index to reveal the records of human activities in the past 160 years on the estuarine sediment and provide scientific prove for investigating land-sea interactions in typical estuaries. The main achievements of the project will help to the further research of the "Source to Sink" process of terrigenous sediments and human activities records in the past hundred years.

黄河沉积物环境磁学研究对深入理解陆源物质从源到汇过程与探索边缘海人类活动记录具有重要科学意义。本课题选取黄河流域主要支流、以及黄河三角洲两钻孔沉积物样品，研究黄河源沉积物的磁性矿物类型、含量以及磁畴信息等环境磁学变化特征，探寻环境磁学的变化规律与控制因素，确定黄河流域沉积物的磁学物源属性指标，并探讨黄河主要支流对干流的贡献；基于现代黄河三角洲和苏北老黄河三角洲两钻孔的环境磁学数据，结合重矿物、地球化学等沉积学指标，详细研究黄河改道前后黄河三角洲环境变化与沉积过程；在此基础上，建立指标参数，揭示160年以来人类活动在黄河沉积物中的记录，为探索我国典型大河海陆相互作用提供科学依据。本课题的主要成果对于探索陆源沉积物从源到汇过程，揭示近百年来人类活动记录等有一定科学意义。

黄河流域作为我国重要的生态屏障区和经济发展区，其环境变化状况一直是关注热点。对黄河流域沉积物开展环境磁学研究对于系统揭示160 a以来人类活动在黄河流域沉积物中的记录、深入理解陆源物质从源到汇过程都具有重要科学意义。针对现代黄河三角洲YRD-1101孔及苏北老黄河三角洲JC-1201孔沉积物，开展了环境磁学、地球化学相关研究。发现黄河1855 a改道前后，沉积物磁性矿物类型基本保持不变都是以亚铁磁性矿物为主，但磁性矿物磁畴变细且磁性矿物含量明显增加；重金属元素含量明显增加，EF指数增加，指示人类活动对沉积物的污染明显加强，初步分析认为一方面与气候的变化有关，另一方面与人类活动，例如：修建大坝、开垦、砍伐树木等有关；同样，针对黄河流域沉积物开展了环境磁学测试研究，确定了黄河流域沉积物磁性矿物种类以亚铁磁性矿物为主，从上游到下游磁性矿物含量增大，而磁性矿物磁畴则表现为上游最粗、中游最细，框定了黄河流域沉积物的磁学物源属性。本课题的研究成果对探索我国典型大河海陆相互作用，揭示近百年来人类活动的记录等具有一定的科学意义，为黄河流域生态环境保护提供了研究数据。