长江下游升金湖沉积物记录的过去千年高分辨率气候环境变化  

HIGH-RESOLUTION PALEOCLIMATIC CHANGES RECORDED IN LAKE SHENGJIN,LOWER REACHES OF THE YANGTZE RIVER OVER THE LAST MILLENNIUM

作　　者：胡洁 汪勇 金院 项超生 吴立 徐仪红 HU Jie;WANG Yong;JIN Yuan;XIANG Chaosheng;WU Li;XU Yihong(Anhui Key Laboratory of Earth Surface Processes and Regional Response in the Yangtze-Huaihe River Basin,School of Geography and Tourism,Anhui Normal University,Wuhu 241002,Anhui;School of Spatial Informatics and Geomatics Engineering,Anhui University of Science&Technology,Haainan 232001,Anhui)

机构地区：[1]安徽师范大学地理与旅游学院,江淮流域地表过程与区域响应安徽省重点实验室,安徽芜湖241002 [2]安徽理工大学空间信息与测绘工程学院,安徽淮南232001

出　　处：《第四纪研究》2022年第2期421-434,共14页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:41771228);安徽师范大学校博士启动金项目(批准号:2017XJJ36)共同资助。

摘　　要：中国东部季风区气候格局具有强烈的时空差异,加强过去千年高分辨率气候变化历史重建及其机制研究对于深刻认识中国东部当今及未来气候变化趋势以及制定应对策略具有重要科学意义。本研究以长江中下游地区典型湖泊升金湖长度为86 cm的沉积岩芯为研究对象,在AMS^(14)C测年数据建立可靠年代框架的基础上,利用沉积物粒度、总有机碳(TOC)、总氮(TN)、碳氮比(C/N)和无机碳(IC)等指标高分辨率重建该流域过去千年以来的气候环境变化。研究结果表明:1)阶段Ⅰ(1000~1350 A.D.),对应中世纪暖期,平均粒径相对较细,TOC、TN、C/N较低,说明湖泊水位总体较高,1100 A.D.后粒度粗粒成分增多和IC波动增长,表明流域气候逐渐向干旱化状态转变;2)阶段Ⅱ(1350~1600 A.D.),进入小冰期前期,平均粒径和IC含量进一步降低,TOC、TN、C/N上升,指示湖泊水位持续升高,气候偏湿润;3)阶段Ⅲ(1600~1850 A.D.),进入小冰期后期,平均粒径增大,表明湖泊流域降水减少,水位下降,流域内湿地植被发育从而使得TOC、C/N增大,IC也迅速增加,湖泊流域气候较为干旱;4)阶段Ⅳ(1850~2000 A.D.),对应现代暖期,平均粒径下降,IC降低,湖泊水位再次上升,气候总体呈暖湿状态,TOC、TN、C/N受气候和人类活动共同影响而持续增长。区域重建结果对比表明,中世纪暖期和小冰期升金湖沉积物记录与长江中下游地区其他研究结果记录的干湿变化较为一致。进一步将升金湖记录与近千年来的东亚夏季风环流、ENSO以及太阳辐照度等记录进行对比分析发现,该地区过去千年以来的气候变化不仅受东亚夏季风变化控制,同时还受到ENSO状态及太阳辐照度变化等显著影响。在中世纪暖期和小冰期后期,以拉尼娜态为主,太阳辐照度较强,升金湖地区气候较为干旱;小冰期前期和现代暖期以厄尔尼诺态为主,升金湖地区气候较为湿润;现代暖期后,升The climate pattern in the monsoon region of China has a strong spatio-temporal difference,the south-north dipolar precipitation mode was revealed between North China and the Yangtze River Basin in the last millennium or even longer.Therefore,in order to improve understanding of the current and future climate change trends in Eastern China,it is of great significance to strengthen the research on high-resolution paleoclimate reconstruction and its driving mechanism in this region.Lake Shengjin(30°15’~30°28’N,116°58’~117°14’E)is located in the lower reaches of Yangtze River in Chizhou City,Anhui Province,China.Lake Shengjin is a freshwater lake with a surface area of 133 km^(2)and consists of upper lake,middle lake,and the lower lake.The lake is situated in a subtropical monsoonal zone with an annual average precipitation of approximately 1600 mm and an average annual temperature of 16.14℃.A 86 cm long continuous sediment core of Lake Shengjin(SJPC19-3)(30°20’N,117°00’E)was retrieved by gravity corer in the shallow water wetland of Lake Shengjin in 2019.A total of 98 samples were separated from the 9~86 cm of the sediment sequence,which was subsampled in 0.5 cm intervals in the range of 9~30 cm and 1 cm intervals in the range of 30~86 cm.We selected three samples of the core SJPC19-3 with the depth of 10 cm,45 cm,86 cm and sent to Beta Analytic Company for AMS;C dating.The age at the bottom of the core SJPC19-3 is about 990±30 cal.a B.P.,indicating that the core has completely covered the process of climate and environmental change in the region of Lake Shengjin during the last millennium.In this study,based on the AMS^(14)C dating,we carried out multi-proxy analyses of lacustrine sediments from Lake Shengjin,including grain size,total organic carbon(TOC),total nitrogen(TN),C/N values and inorganic carbon(IC)to reconstruct paleoclimatic changes over the last millennium.The paleoclimatic changes of last millennium,based on our results,is divided into four stages:(1)Period Ⅰ(1000~1350 A.D.),co

关 键 词：升金湖 湖泊沉积 中世纪暖期 小冰期 气候变化 

分 类 号：P534.632[天文地球—第四纪地质学] P941.78[天文地球—古生物学与地层学]