黄河三角洲周边海域表层沉积物地球化学特征分布及影响因素

Controlling factors and distribution of geochemical characteristics of the surface sediments in the Yellow River Delta

  • 摘要: 基于黄河三角洲周边海域180个站位的表层沉积物资料,分析了16种地球化学元素的分布特征,利用多元统计分析、数值模拟、元素比值等方法,探讨了沉积物粒度、水动力环境以及物质来源等因素对于表层沉积物地球化学特征的影响。在地球化学元素分布的基础上,运用聚类分析将研究区划分为6个地球化学区域。I-2区、I-3区、II-1区和II-2区东部的大部分元素(TFe2O3、Al2O3、MgO、MnO、K2O、Cr、Ni、Cu)含量较高,沉积物粒度较细;I-1区、II-3区的SiO2含量较高,沉积物粒度较粗。潮流控制着沉积物的起动及运移,潮余流影响着细粒沉积物以及多数元素的富集,水动力作用通过改变沉积物粒度空间格局进而控制这些元素的分布。研究区黄河物质输入以及人类活动影响的区域性差异明显,黄河物质输入主要作用于现行黄河口海域,人类活动对埕北老黄河口的Cd、Zn、Pb、P2O5影响最为显著。自然因素是控制研究区表层沉积物地球化学特征分布的主要原因,人类活动则进一步改变了部分元素的空间分布规律。

     

    Abstract: The distribution characteristics of 16 elements in the surface sediments from 180 sites in the Yellow River Delta were analyzed. The effects of sediment grain size, hydrodynamic environment, and material sources on geochemical characteristics of the surface sediments were analyzed using multivariate statistical analysis, numerical modelling, and element ratio; and the main controlling factors of geochemical characteristics of surface sediments in the study area were discussed. Based on the distribution of geochemical elements, the study area was divided into six geochemical regions by cluster analysis. Most of the elements (TFe2O3, Al2O3, MgO, MnO, K2O, Cr, Ni, Cu) in Regions I-2, I-3, II-2, and the eastern part of II-1 are characterzied by elevated concentrations, and the sediment grain size in these areas is fine. The contents of SiO2 are higher in Regions I-1 and II-3, and the sediment grain size is coarser. Results show that tidal current controled the initiation and transport of sediment in the study area, and tidal residual currents affected the enrichment of fine-grained sediment and most elements. Local hydrodynamic environment controlled the spatial pattern of grain size in surface sediments. Obvious regional differences in material input from the Yellow River and human activities were revealed. The modern Yellow River estuary was strongly controlled by material input from the Yellow River. Human activities had a stronger impact on Chengbei Old Yellow River estuary, especially Cd, Zn, Pb and P2O5. Natural factors were the main factors on the geochemical distribution of surface sediments, while human activities further alytered the spatial distribution of some elements.

     

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