近几十年来人类活动导致河口低氧现象不断恶化，成为"死亡区域"而备受各界关注。但河口发生季节性低氧是一种自然过程，可能在全新世某一阶段便开始出现，因此对低氧发育历史过程的研究正在成为新的热点。长江口是全球河口低氧发育最显著的区域之一，其近现代过程和沉积记录已得到较详细的研究。申请课题拟通过近现代低氧沉积记录的系统研究，包括运用有孔虫鉴定、氧化还原敏感元素和同位素、有机元素分析等手段，建立低氧沉积记录的判别标志；将该方法运用于水下三角洲三个连续取芯的钻孔全新世地层的低氧事件判别，结合精确的AMS 14C测年，以及全新世古洪水、海平面变化、台湾暖流、沿岸流与东亚冬季风活动规律的研究，详细探讨全新世长江口低氧区形成、演化历史与规律，及其控制因素与机制，增进对河口缺氧的自然过程和人类活动影响态势的理解，为LOICZ-II、LDE和RiOMars等研究计划提供一个典型的实例、可借鉴的方法与理论。

Coastal hypoxia has been significantly deteriorated by human activities in the recent decades,arising broad concerns of scientists and the public as a "dead zone". The occurrence of seasonal hypoxia off the estuaries is actually a natural phenomenon, and it may have occurred since the Holocene. Reconstruction of hypoxia history has therefore become a research hotspot. The Changjiang Estuary is one of the most widespread hypoxia zones in the world, and its modern and recent behaviors and their sedimentary records have been studied relatively in detail. This research proposes to set up multi-proxy methodology for hypoxia deposit study through systematic analyses of modern and recent sediments in the hypoxia region, involving foraminiferal identification, and measurements of redox sensitive elements and isotopes, organic elements, and so on. The multi-proxy method will be employed to study Holocene hypoxia deposits among three borehole cores from the Changjiang Subaqueous Delta. It will be further discussed the hypoxia development and evolution history, and its controlling factors and mechanism in the Holocene through time-series analyses of their occurrences in comparison with paleo-river floods, sea-level change, and activities of Taiwan Warm Current, China Coastal Current, and East Asia Winter Monsoon. It aims to improve our understanding of the development history and future trend of coastal hypoxia under the natural condition and increasing human activities, and contribute a new representative study case, some referential methods and hypothesis to other LOICZ-II, LDE, and RiOMars studies.