基于典范对应分析的铅锌矿尾砂坝坍塌污染土壤特征研究

Relationships between Soil and Environment in Pollution of Agricultural Soils from a Tailing Spill at a Pb—Zn Mine Based on Canonical Correspondence Analysis

分析重金属与土壤性质之间的相互关系,可以为土壤污染控制及修复提供科学依据。以广西阳朔思的村铅锌矿尾砂坝坍塌后所污染的岩溶农田为研究对象,采用典范对应分析方法研究土壤重金属全量-土壤性质之间的关系。结果表明,尾矿砂来源于铅锌铜共生矿。典范对应分析显示,土壤有机碳与全铅、全锌、全铜的距离最近,并与归一化的全量重金属呈极显著正相关,说明经过近40 a的耕作,土壤有机碳仍然处于较低水平。速效磷与土壤全铅、全锌、全铜呈显著负相关,与岩溶土壤pH降低后导致水溶性P与Pb生成溶解度极低的氯(羟基)磷酸铅盐化合物有关,说明污染源的pH值是影响P—Pb—Zn—Cu相互作用过程的重要因素。此外,该区面源污染时空分异显著,今后在岩溶区开展重金属污染土壤治理时必须对整个区域进行定量的不确定性分析。

The collapse of the tailing dam in the Laochang Pb/Zn mine of Yangshuo, Guangxi province led to the spread of mining waste in Sidi village at karst area along the irrigation river. 31 samples along the contaminated irrigation river were analyzed for total zinc, total lead, total copper, pH, soil organic carbon, total nitrogen, available nitrogen, available phosphorous, C/N and cation exchange capacity in surface soil to assess the soil pollution level. Moreover, the method of canonical correspondence analysis （CCA） was employed to reveal the relationships between soil and environment. The results show that the Pb/Zn/Cu mine of the tailing sand is a multimineral orebody. Though after almost 40 years farming, the soil organic carbon is still quite low. From the canonical correspondence analysis map, it will be found that the total lead, zinc and copper has the high correlation and the normalized total heavy-metals has the positive correlation with the soil organic carbon. Moreover, under the effect of mining water, the karstic soil has to decrease the soil pH, which leads to this area with acid environment character. Then, the soluble P and Pb is easy to generate the low solubility of chlorine （hydroxyl） lead phosphate salt compound, because the available phosphorus has the negative correlation with total lead, zinc and copper, which means that the environment is an important factor to control the reaction process of P--Pb--Zn--Cu. At last, the non-point source pollution caused by the Pb--Zn mine tailing will produce many uncertain factors to harness the heavy metal pollution at karst area.