现代黄河三角洲沉积物粒度端元特征及其对河道变迁和人类活动的响应

End-member characteristics of sediment grain size of modern Yellow River Delta sediments and their response to channel shifts and human activities

黄河三角洲沉积物记录了长时间尺度黄河流域环境变化,对流域河流改道和水库建设等自然和人类活动响应敏感。本研究以黄河1976年以来入海口附近陆上三角洲YDC钻孔为研究对象,采用参数化端元(EM)分析模型对YDC钻孔的粒度数据进行分析,结果表明:①EM1和EM2由粒径较细的黏土和细粉砂组成,为黄河长距离搬运弱水动力条件下沉积,EM3和EM4为粗粉砂组分,为较强动力条件下波浪和潮流作用沉积;②对比河道变迁和人类活动等资料,结合前人黄河口沉积速率研究数据,表明YDC钻孔粒度特征变化显著的界面可以作为黄河口沉积物定年的参考点;③YDC钻孔粒度参数和端元数据敏感地响应于1976年以来黄河改道清水沟入海、龙羊峡水库建设、黄河改道清8汊入海等自然和人类活动。研究结果对黄河三角洲河口治理和沿岸工程建设具有重要现实意义,并可为黄河流域生态保护与高质量发展提供科学依据。

Yellow River Delta sediments record environmental changes in the Yellow River basin at long time scales,and respond sensitively to natural and human activities such as river diversions and reservoir construction in the basin.We analyzed the grain size distribution of core YDC from onshore delta since 1976 near the river mouth were analyzed using a parametric end-member analysis model.Results show that EM1 and EM2 are composed of fine-grained clay and fine powder sand,deposited under weak hydrodynamic conditions for long distance transport in the Yellow River,while EM3 and EM4 are coarse powder sand fractions,deposited by wave and tidal action under stronger dynamic conditions.By comparing the data on channel alteration and human activities,and combining data from previous studies on sedimentation rates in the Yellow River estuary,we found that significant changes in grain size characteristics could be used as reference points for sediment age determination.The grain size parameters and end element data reflect the natural and human activities since 1976,such as the diversion of the Yellow River from Qingshuigou to the sea,the construction of the Longyangxia Reservoir,and the diversion of the Yellow River from Qingbacha to the sea.This study provide a reference for the management of the Yellow River Delta estuary and coastal engineering construction,and a scientific basis for ecological protection and high-quality development of the Yellow River basin.