蕉门水道沉积物重金属分布特征及定量源解析

Spatial distribution and quantitative source identification of heavy metals in sediment cores of Jiaomen Waterway

为探究珠江口感潮河段蕉门水道沉积物重金属的空间分布特征、污染风险和潜在来源,对沉积物柱状样的基本理化性质、重金属地球化学形态进行分析.结果表明,沉积物重金属(Cd、Cr、Zn、Ni、Cu和Pb)浓度较珠江口背景值更高,其中Cd、Zn、Cu和Pb浓度随盐度的升高呈显著下降趋势(p<0.05),电导率(EC)、pH值和沉积物有机碳(SOC)是影响重金属空间分布格局的主要因素.此外,沉积物重金属的主要形态不一,且酸可溶态Zn、Ni、Cu和Pb随盐度升高大致呈下降趋势,而残渣态则相反.沉积物重金属污染程度和潜在生态风险在盐度梯度上大致呈现下降趋势,Cd是导致高生态风险的主要元素.人类活动是导致沉积物Cd、Cu、Pb、Zn、Fe和Mn富集的主要原因:其中农用化学品施用是沉积物Cd和Cu的主要污染成因,Pb来源于交通运输活动,Zn、Fe和Mn则与工业活动密切相关;其余金属元素(Ti、Ni、Cr和Co)主要源自母质矿物的自然风化.

To explore the spatial distribution characteristics,pollution risks and potential sources of heavy metals in the sediments of Jiaomen Waterway,a tidal reach of the Pearl River estuary,six cores to a depth of 15cm were collected with basic physicochemical properties and geochemical fractions of heavy metals analyzed for all sediment samples of every 1cm.The results showed that the concentrations of heavy metals of Cd,Cr,Zn,Ni,Cu and Pb in sediments were higher than those of the background value in the Pearl River estuary,and conductivity(EC),pH and sediment organic carbon(SOC)were found to be the main factors affecting the spatial distribution pattern of heavy metals.e.g.,the concentrations of Cd,Zn,Cu and Pb decreased significantly with the increase of salinity(p<0.05).In addition,the main fraction of of heavy metals changed accordingly with salinity,i.e.,the acid soluble fraction of Zn,Ni,Cu and Pb showed a general decreasing trend with the increasing salinity,while an opposite trend was observed for the residual fraction.The pollution level and potential ecological risk of sediment metals generally descended with increase in salinity,and Cd was identified to be the main element inducing ecological risks.Anthropogenic activities were considered the main cause for enrichment of Cd,Cu,Pb,Zn,Fe and Mn in sediments,with agrochemicals recognized as the main source for sediment Cd and Cu,traffic activities for Pb,and industrial activities for Zn,Fe and Mn,while natural weathering of parent minerals were judged as the principal origins of other metals such as Ti,Ni,Cr and Co.