长江口及其邻近海域表层沉积物中部分金属元素赋存形态研究

A Study on the Geochemical forms of Metal Elements in the Surface Sediments of Yangtze Estuary and Its Adjacent Sea Areas

2014年6月在长江口及其邻近海域采集了表层沉积物样品,用连续提取法对Cr、Co、Ni、Cu、Zn、Al、Mn和Fe金属元素的赋存形态进行分离,即分作可交换态(EXC)、碳酸盐结合态(CARB)、铁锰氧化物结合态(ERO)、有机结合态(OSM)和残渣态(RES)并测定了含量。结果表明,长江口及其邻近海域表层沉积物中的Cr主要赋存在OSM态中,Mn主要赋存在CARB态中,Ni在OSM态和ERO态含量相当,Co、Cu、Zn、Al和Fe元素主要赋存在ERO态中。长江口及其邻近海域D断面表层沉积物中Cr、Co、Ni、Cu、Zn、Al、Mn和Fe元素的非残渣态含量随着离岸距离的增加而逐渐降低。ERO态金属元素随着沉积物中铁锰水合氧化物的含量的升高而增加,且ERO-Cr、Co、Ni、Cu、Zn、Al与铁锰水合氧化物含量之间有较好的相关性,说明这些金属元素受到铁锰水合氧化物的影响。各金属元素非残渣态总量与ERO-Fe含量之间相关性也较好,说明各元素非残渣态受控于其各自主要的赋存形态。

Surface sediment samples from Yangtze Estuary and its adjacent sea areas were collected in June 2014. Geochemical forms of non-residual, i. e., exchangeable （EXC）, carbonate combined （CARB）, easily reducible （ERO~ iron and manganese oxyhydroxide combined）, organic matter com- bined （OSM） of Cr, Co, Ni, Cu, Zn, A1, Mn and Fe, were extracted and determined with a sequential chemical leaching method. In the surface sediments of Yangtze Estuary and its adjacent sea areas, the major chemical form of chromium was OSM, the major chemical form of manganese was CARB, OSM and ERO were the major chemical form of nickel, and the major chemical form of the other metals of Cu, Co, Zn, A1 and Fe was ERO. The total amounts of non-residual fractions of metals （Cr, Co, Ni, Cu, Zn, A1, Mn and Fe） in D profile of Yangtze Estuary and its adjacent sea areas decreased with the increasing the distances offshore. However, ERO forms of metals （Cr, Co, Ni, Cu, Zn and AI） in- creased with the increasing content of iron and manganese oxyhydroxide with a good correlation, which illustrated the effect of iron and manganese oxyhydroxide on metals. Correlations between the heavy metals bound to non-residual and Fe bound to Fe-Mn oxides were also good, which indicated that the variations in total contents of non-residual fractions of metals （Cr, Co, Ni, Cu, Zn, A1, Mn and Fe） were mainly controlled by their dominant chemical forms.