云南省武定县土壤重金属地球化学分布特征及其来源浅析

为探明西南地区耕地土壤重金属污染的分布特征及来源,选取云南省武定县优耕区为研究区,在分析1802件表层土壤和4条剖面土壤重金属含量的基础上,运用地累积指数法评估重金属污染风险,利用地统计分析、单因子方差分析、正定矩阵分析探讨重金属的空间分布特征、污染水平及潜在来源。8种重金属与云南省背景值相差较小,其中Cr、Ni平均含量高于云南省背景值,是其背景值的1.75和1.14倍,As、Cu、Hg、Ni、Pb和Zn低于其背景值。8种重金属元素呈现东高西低、南高北低的分布趋势,异常区分布规律明显。地累积指数结果表明,8种重金属中仅Cd存在轻微污染,其余元素均处于无污染水平,与以往认为西南地区是地质高背景区、土壤污染严重有较大出入,需要对西南重金属高背景区的观点进行重新认识和修订。研究区内8种重金属主要有3个污染源:矿业开采源、肥料和交通污染源和成土母质源。其中,As、Cu、Hg主要受迤纳厂铜矿开采的影响; Pb、Cd、Zn受刺竹箐铅锌矿床的开采、交通污染和肥料施用的共同影响; Cr、Ni受成土母质影响较大。

Geochemical distribution characteristics and sources of heavy metals in soils of Wuding County, Yunnan Province

The purpose of this work was to clarify the distribution characteristics and sources of heavy metal pollution in cultivated soils in southwest China. Taking the excellent farming area of Wuding county, Yunnan Province as the target, we analyzed 1802 surface soils and four profiles. Based on these data, the geo-accumulation index was used to assess the risk of heavy metal pollution. Then methods of geo-statistics, one-way analysis of variance and positive definite matrix analysis were used to investigate the spatial distribution characteristics, pollution levels and potential sources of heavy metals in the study area. Results show that the background values of eight heavy metals differ a little from those of entire Yunnan Province. Of them, average content of Cr and Ni is higher than that of Yunnan Province, 1.75 and 1.14 times the background value, respectively. Content of As, Cu, Hg, Ni, Pb and Zn is lower than the background. Overall, the eight heavy metal elements are high in east and south and low in west and north with an obvious regularity. The cumulative index shows that only Cd in 8 heavy metals produces slight pollution, and other elements are in a non-pollution level, which is much different from previous studies which claimed that the southwest China is a high geological background area with serious soil pollution. So this issue needs further investigations and research. It is noted that these eight heavy metals in the study area have three main sources: mining, fertilizer and transportation, and soil parent material. Specifically, arsenic, copper and mercury are mainly from Yinachang copper mining; lead, cadmium and zinc are from Cizhuqing deposit mining, traffic pollution and fertilization; and Cr and Ni are from parent material of soils.