摘要
自1950年以来,长江入海输沙量呈阶段性减少趋势;作为长江远端泥,长江入海输沙量的“减沙”效应在浙闽沿岸泥质区是否有相应的沉积信号?若有,该如何进行提取和解译?为探讨以上问题,在浙闽沿岸泥质区采集柱状样5根,进行了高分辨率(2 mm)的粒度测试,并通过端元分析手段分离出4个端元。结合研究区物源及水动力的空间差异,发现各端元有其特定的指示意义:EM1组分(众数粒径约为2μm)为长江来源的极细粒物质;EM2组分(众数粒径约为10μm)主要为长江及浙闽沿岸中小河流的细颗粒物质,但以长江为主;EM3组分(众数粒径约为80μm)主要为台湾暖流带来的较粗粒物质;EM4组分(众数粒径约为200μm)为长江输运的粗颗粒物质。进一步分析发现,EM1组分对长江入海输沙量的阶段性减少有较好的响应关系:由浙闽泥质区北部至南部响应强度依次降低;在响应时间上存在滞后现象,且从北到南滞后时间增加,由北部的4~6年增加至南部的10~14年。总体来看,细颗粒组分更能反映长江流域变化信息,且泥质区的不同位置对流域变化信息的响应强度差异显著。
Since 1950,the sediment load of the Changjiang River entering the sea has been stepwise decreasing.As the distal mud of the Changjiang River,whether the signal of“sediment load reduction”was recorded in the Zhe-Min coastal mud?If so,how to extract and interpret these sedimentary information?In order to discussing this scientific problem,5 sediment cores were collected in the Zhe-Min coastal mud;in addition,high resolution grain size analysis(2 mm)was conducted,and four end members were obtained through end-member(EM)model decomposing.Combined with the analysis of the spatial discrepancy in provenance and hydrodynamics of the study area,the specific indicative significance of each EM was revealed:EM1(with the modal grain size about 2μm)is originated from extremely fine-grained sediment of the Changjiang River;EM2’s(with the modal grain size about 10μm)origin is predominated by the Changjiang River,and small part is contributed by the middle and small sized rivers of Zhe-Min coast;EM3(with the modal grain size about 80μm)mainly consists of coarse-grain sediment might be provided by Taiwan Warm Current;EM4(with the modal grain size about 200μm)is also characterized by coarsegrain sediment,and may be contributed by the Changjiang River.Further analysis indicated that,the EM1 variation was in agreement with the sediment stepwise reduction of the Changjiang River;however,the response intensity gradually decreased from the north to the south.In addition,the hysteresis existed in response time,and the retardation time increased from 4−6 years in the north to 10−14 years in the south.In general,fine-grained sediment could better reflect the Changjiang River catchment change information,and response intensity exhibited significant difference in different areas of the Zhe-Min coastal mud.
作者
刘胜璟
高建华
徐笑梅
石勇
舒卓
吴昊
元冰瑜
贾建军
Liu Shengjing;Gao Jianhua;Xu Xiaomei;Shi Yong;Shu Zhuo;Wu Hao;Yuan Bingyu;Jia Jianjun(School of Geography and Ocean Science,Nanjing University,Nanjing 210023,China;Key Laboratory of Coast and Island Development of the Ministry of Education,Nanjing 210023,China;State Key Laboratory of Estuarine and Coastal Research,East China Normal University,Shanghai 200062,China)
出处
《海洋学报》
CAS
CSCD
北大核心
2021年第3期105-115,共11页
基金
国家自然科学基金(41776048,41876092)。
关键词
浙闽泥质区
粒度
端元分析
长江入海输沙量
the Zhe-Min coastal mud
sediment grain size
end-member(EM)analysis
sediment entering into the sea from the Changjiang River
