近百年来人类活动对鸭绿江口河床演变影响的轻矿物沉积记录

研究了鸭绿江西汊道柱状沉积物中0.063~0.125 mm粒级的碎屑轻矿物组成和垂向分布特征,并寻找到了具有指"相"意义的代表性轻矿物和其他特征指数。结果表明,沉积记录中存在着明显的河流沉积与浅海沉积交替出现的情况,结合210Pb测年数据和前期研究成果,揭示了该区域近百年来人类活动对河床演变的深刻影响。其中,水库建设的影响最大,形成了难以逆转的河势;其次是围垦的影响,影响相对较小的是港口建设和河道整治。

Sedimentary Records of Light Mineral Representing the Influence of Human Activities on Riverbed Evolution in Yalu River Estuary in Recent 100 Years

The components and vertical distribution characteristics of detrital light minerals with size fraction of 0.063～0.125 mm in core sediments were studied.The representative light minerals with facies significance and other characteristic indexes were also found out in the research.The result showed that there were obvious alternation between river deposits and shallow sea deposits in sedimentary records.Combined with the contrast between dating data of 210Pb and historical materials,this study revealed the deep influence of human activities on riverbed evolution.Among the factors,reservoir construction had the dominant influence,which made the river regime change irreversibly.The second was the influence of enclosing river courses for cultivation.The influence of harbor construction and river regulation was comparatively little.