华南某金矿下游河道砷镉分布特征

对华南某金矿下游河道砷、镉分布特征进行了初步研究,在金矿下游河道沿程布设7个沉积物采样点及两个河道断面,分析了沉积物及断面土壤的砷、镉、铬、铜、镍、铅、锌含量。采用Tessier连续提取法分析沉积物中砷、镉等重金属的形态。砷含量高达10 208⁷0 621 mg/kg,镉含量达2.870 621 mg/kg,镉含量达2.8¹0.2 mg/kg。沉积物中砷、铅元素含量沿水流方向总体呈现减少趋势,铬、铜元素含量沿水流方向呈现增加趋势,镉元素含量沿水流方向先增加后减少。上游断面沉积物砷、镉等重金属浓度由河流中泓线向河岸方向增加,砷含量由16 617 mg/kg增加至53 197 mg/kg;下游断面则反之,砷含量由16 860 mg/kg减少至384mg/kg。沉积物中砷、镉等重金属元素主要以铁锰氧化态、有机结合态和残渣态的形式存在。

Distribution Feature of Arsenic and Cadmium in Downstream River of a Gold Mine in South China

This paper conducted a preliminary study about the downstream river Arsenic, Cadmium distribution characteristics of a gold mine in southern China. Seven sediment sampling points and two cross sections of river were set along the downstream river. The contents of Arsenic, Cadmium, Chromium, Copper, Nickel, Plumbum and Zinc in the sediment and the cross-section soil were analyzed. Tessier sequential extraction method was used to analyze the forms of Arsenic, Cadmium and other heavy metals in the sediment. The contents of Arsenic and Cadmium in the sediment were up to 10 208~70 621 mg/kg and 2.8~10.2 mg/kg. The contents of Arsenic and Lead in the sediment decreased along the flow direction, while the contents of Chromium and Copper increased. The content of Cadmium increased first, then decreased along the flow direction. The concentrations of Arsenic, Cadmium and other heavy metals in the sediment of upstream cross-section increased from middle to shore side, among them the content of Arsenic increased from 16 617 mg/kg to 53 197 mg/kg. While the downstream cross-section vice versa, the content of Arsenic decreased from 16 860 mg/kg to 384 mg/kg. The existing forms of Arsenic, Cadmium and other heavy metals in the sediment were mainly Fe-Mn oxide, organic and residual.