典型铅锌矿化区不同土地利用类型土壤重金属污染特征与评价

选取云南者海典型铅锌矿区周边冶炼区（A）、粮食主产区（B）、保护区（C）三个区域土壤为研究对象，分析三个区域内林地（LD）和耕地（GD）土壤pH、总碳（TC）、总氮（TN）、总磷（TP）和5种重金属（Hg、Cd、Pb、Zn、Cu）含量，利用典范对应分析（CCA）研究不同土地利用类型下它们之间的关系，基于系统熵值与重金属生物毒性改进灰色聚类评价法对研究区重金属污染程度进行评价。结果表明，A、B、C三区土壤的5种重金属均超过云南省土壤背景值，且含量A区 > B区 > C区，所有土壤样品Hg、Cd、Pb、Zn、Cu平均含量分别为7.24、1.53、1 794、2 892、210 mg/kg；LD土壤重金属含量普遍高于GD。研究区土壤pH总体呈弱酸性，但A区土壤受矿业活动影响呈弱碱性。TC、TN含量和C/N值均表现出LD大于GD，但TP含量表现为GD显著大于LD （P<0.05）。CCA分析表明LD和GD土壤pH与Cd和Cu呈负相关，与Zn和Pb呈正相关，且pH对重金属含量的影响最大；TC、TP与重金属Cd和Cu在LD土壤中呈正相关，在GD土壤中呈负相关。改进灰色聚类评价结果表明重金属污染程度均表现为LD大于GD；A区污染最严重且均呈重度污染，B区次之，C区污染程度最轻。经比较本文改进的灰色聚类评价法在准确性和灵敏度方面优于传统方法。

Characterization and Assessment of the Heavy Metal Pollution in Soils of Different Land Use Patterns around a Typical Lead-zinc Mineralization Area

Soils from three regions, Smelting Zone(A), Production Zone(B), and Reservation Zone(C), surrounding the typical lead-zinc mineralization area of the Zhahai Town, Huize County, Yunnan Province, were selected as research objects, and physicochemical properties of soil including pH, total carbon(TC), total nitrogen(TN), total phosphorus(TP) and contents of 5 heavy metals (Hg, Cd, Pb, Zn, Cu) in forest lands (LD) and cultivated lands (GD) were determined and investigated. The Canonical Correspondence Analysis (CCA) was used to explore relationships between soil physicochemical properties and heavy metal contents in soils of different land use patterns. An improved gray clustering evaluation method based on the entropy value and biological toxicity of heavy metals was performed to assess the pollution degree of heavy metals in soils of the study area. The results showed that, the heavy metal concentrations in all zones (A, B and C) exceeded the soil background value of Yunnan, and the heavy metal contents in different regions showed an order of A > B > C, the average contents of Hg, Cd, Pb, Zn and Cu in all soil samples were 7.24, 1.53, 1 794, 2 892 and 210 mg/kg, respectively. Generally, the contents of heavy metals in LD were higher than those in GD. Additionally, most soils in the study area were slightly acidic except ones in Zone A which were slightly alkaline. TC, TN and C/N in soils of LD were higher than those of GD, but TP content was significantly lower in LD than in GD (P<0.05). The CCA analysis showed that soil pH values of LD and GD had a negative correlation with contents of Cd and Cu, and had a positive correlation with contents of Zn and Pb, and soil pH showed the greatest effect on the difference of heavy metal contents. TC, TP and contents of Cd, Cu exhibited opposite correlations, positive in LD soils but negative in GD soils. The improved grey clustering evaluation showed that the degree of heavy metal contamination in LD was much greater than that in GD. The soils in Zone A had the most serious pollution level, followed by soils in Zone B and then soils in Zone C, which were contaminated slightly. Compared to conventional methods, the improved gray clustering evaluation method established in this study showed advantages in both accuracy and sensitivity.