贵州晴隆锑矿尾砂中锑和砷的生物有效性及生态风险评价

为探明锑矿尾砂中锑(Sb)和砷(As)的形态分布特征及生态风险,选取贵州省晴隆锑尾矿库为研究对象,在尾砂剖面上(0~330 cm)采集样品33件,基于物相表征分析、冗余分析(RDA)及生态风险评价等方法,阐明了锑和砷在尾砂剖面上的形态分布及变化特征,并对其生态风险进行评价。结果表明:尾砂中主要以石英(SiO₂)、辉锑矿(Sb₂S₃)及方解石(CaCO₃)3种矿物存在;尾砂浸出液重金属浓度远低于毒性浸出标准;尾砂中Sb含量明显随深度增加而增加,而As含量在剖面上分布相对均匀。Sb各形态含量顺序为残渣态(1196.17 mg/kg)>可还原态(131.46 mg/kg)>弱酸提取态(54.07 mg/kg)>可氧化态(41.59 mg/kg),而As各形态含量顺序为残渣态(282.27 mg/kg)>可还原态(71.1 mg/kg)>可氧化态(42.06 mg/kg)>弱酸提取态(5.12 mg/kg);Sb和As的有效态含量分别占总量的16.94%和30.34%,其主要形态是可还原态。基于重金属总量的内梅罗综合污染指数评价法和潜在生态危害指数法的评价结果为存在重度污染和严重环境生态风险;基于重金属形态含量的风险评估编码法(RAC)和次生相原生相分布比值法(RSP)评价结果为低污染和低生态风险。基于重金属形态含量的评价方法可更客观准确地评价其可能对环境产生的潜在生态风险。

BIOAVAILABILITY AND ECOLOGICAL RISK ASSESSMENT OF Sb AND As IN TAILINGS OF QINGLONG ANTIMONY MINE IN GUIZHOU

A detailed study of morphological distribution characteristics and ecological risks of typical heavy metals in antimony tailings was analyzed. 33 samples of tailings in cross-section(0~330 cm) were collected from Qinglong antimony tailings pond located in Guizhou, China. The morphological distribution and change characteristics of two typical heavy metals of antimony(Sb) and arsenic(As) in the tailings profile, based on phase characterization analysis, redundant analysis(RDA) and ecological risk assessment methods were illustrated, meanwhile, the environmental and ecological risks of heavy metals were evaluated. The results showed that the tailings were mainly composed of three minerals, quartz(SiO₂), stibnite(Sb₂S₃) and calcite(CaCO₃). It was found that the concentration of heavy metals in the tailings leaching solution was much lower than the toxic leaching standard value. The results indicated that Sb content in the tailings positive correlated with the depth, and the As content was relatively evenly distributed on the profile. Sb existed in tailings in the form of residue fraction, and in the sequence of residue fraction>reducible fraction>oxidizable fraction>weak acid extraction fraction, but the content of As was in the sequence of residue fraction>reducible fraction>weak acid extraction fraction>oxidizable fraction. The effective fraction content of Sb and As accounted for 16.94% and 30.34% of the total mass respectively, mainly in reducible state form. Based on the total amount of heavy metals, the Nemeiro comprehensive pollution index and the potential ecological hazard index results illustrated that there were severe pollution and environmental and ecological risks. The risk assessment coding method(RAC) and the secondary phase primary phase distribution ratio method(RSP) based on the form content of heavy metals, could evaluate the potential ecological risks to the environment more objectively. The evaluation result showed the tailings pond was with low pollution and low ecological risk.