近三百年来长江口泥质区沉积环境变化及与低氧关系的初步分析  

The response of sedimentary records in the mud area of the Changjiang Estuary to hypoxia in the last 300 years

作　　者：赵亚青 周亮 赵宁[1] 盛辉 汪亚平 ZHAO Yaqing;ZHOU Liang;ZHAO Ning;SHENG Hui;WANG Yaping(State Key Laboratory of Estuarine and Coastal Research,East China Normal University,Shanghai 200241,China;School of Geography,Geomatics and Planning,Jiangsu Normal University,Xuzhou 221116,China)

机构地区：[1]华东师范大学河口海岸学国家重点实验室,上海200241 [2]江苏师范大学地理测绘与城乡规划学院,江苏徐州221116

出　　处：《海洋通报》2021年第1期70-83,共14页Marine Science Bulletin

基　　金：上海市教育委员会科研创新计划(2019-01-07-00-05-E00027);国家自然科学基金(41625021,41706096)。

摘　　要：近年来全球大型河口区低氧事件频发,严重威胁环境和生态系统健康。因缺少长时间序列的观测资料,人们对历史时期河口陆架区域生态环境演化,尤其是低氧事件发生的历史认识不足。本文基于210Pb、137Cs和光释光测年技术,以长江水下三角洲现代低氧区沉积物柱状样为研究对象,通过分析沉积物的粒度参数、氧化还原敏感元素、TOC、TN和碳氮同位素等指标,探究了该区域沉积环境的演化历史。结果显示,近三百年来长江口低氧区的演化大致可分为四个阶段:1740—1800年该区域可能存在低氧环境;1800—1850年低氧情况有所缓解;1850—1970年在人类活动影响开始加剧的背景下,低氧事件发生频率开始增加;1970年后由于入海营养物质排放通量增加,加之海温上升和入海水沙通量变化等多因素综合影响导致长江口低氧区面积和发生频率也显著增加。该结果可为了解长江口泥质区历史低氧环境的演化及现代长江口低氧环境的发育过程提供参考。There have been frequent occurrences of hypoxia in many large estuaries all over the world in recent years,which threaten the health of the environment and ecosystem.Due to the lack of long-term observational data,the understanding of the environment evolution in the continental shelf and estuarine regions is insufficient,especially for the occurrence of hypoxia.In this study,we analyze sediment grain size,redox sensitive elements,TOC,TN,carbon and nitrogen isotopes of a sediment core retrieved from the modern hypoxic zone of the Changjiang subaqueous delta to reconstruct the history of hypoxia in the Changjiang estuarine mud area in the past~300 years.The results show that the evolution of the Changjiang estuarine hypoxic zone during this period can be roughly divided into four stages:a possible hypoxic environment in this area during 1740-1800;lessened hypoxia during 1800-1850;rising frequency of hypoxia during 1850-1970 together with the emerging impact of human activities;and significantly increased occurrence rate and area of hypoxia after the 1970s,coupled with the increase of nutrients inputs into the Changjiang Estuary and the integrated influence of factors such as higher surface sea temperature and changes in sediment fluxes.This study provides new clues for understanding long-term hypoxia changes in the mud area of the Changjiang Estuary.

关 键 词：低氧区 沉积记录 氧化还原敏感元素 长江口 水下三角洲 

分 类 号：P736.2[天文地球—海洋地质] P736.4[天文地球—海洋科学]