珠江口磨刀门水体中重金属分布、分配特征及其影响因素

Heavy metal distribution patterns and their influence factors in Modaomen estuary of the Pearl River

本文利用2018年1月盐水上溯期间在磨刀门区域所获得的现场调查资料,分析该区域的重金属污染现状及空间分布特征,探究重金属的迁移转化特点以及盐度等环境因素对重金属分配结果的影响。基于水体盐度及层化水平将研究区域分为淡水区、混合区及咸水区。结果表明,颗粒态与溶解态重金属含量在淡水区与咸水区之间存在显著差异,颗粒态重金属含量均呈现出由陆向海方向随盐度增加而降低的趋势,各元素的空间变异程度依次为Cd>Cr>Zn>Pb>Cu>As>Ni>Co;溶解态Pb、Cr、As、Co浓度沿向海方向呈逐渐升高趋势,而Cd、Cu、Ni、Zn浓度则呈现“低—高—低”的变化特征,各元素的空间变异程度依次为Zn>Cr>Cd>Pb>Cu>Co>As>Ni。重金属的固液分配系数沿向海方向呈逐渐下降趋势,主成分分析结果表明,盐度和悬浮物浓度是影响磨刀门河口重金属分配的主要环境因素。

Based on the field data obtained in Modaomen estuary during the salt intrusion period in January 2018,the contamination level and distribution characteristics of heavy metals in this area were analyzed and the influence of environmental factors on the transformation and partitioning of heavy metals were studied.The study area was divided into fresh water zone,mixed zone and salt water zone based on salinity and water stratification level.The contents of particulate and dissolved heavy metals had significant difference between fresh water zone and salt water zone.The particulate heavy metals showed a decreased trend with the increase of salinity.The order of variation coefficients in the spatial distribution of particulate heavy metals was Cd>Cr>Zn>Pb>Cu>As>Ni>Co.The concentrations of dissolved Pb,Cr,As and Co increased gradually in the seaward direction,while the concentrations of Cd,Cu,Ni and Zn showed a"low-high-low"distribution pattern.The order of variation coefficients in the spatial distribution of dissolved heavy metals was Zn>Cr>Cd>Pb>Cu>Co>As>Ni.The partitioning coefficients decreased gradually in the seaward direction.Results of the principal component analysis showed that salinity and suspended sediment concentration are the main environmental factors that affect the partitioning of heavy metals in the estuary.