山东省沂源县土壤重金属来源分布及风险评价

为建设高标准农田及保证食品安全,对土壤重金属污染状况进行精确评估极为关键。选取山东省山地丘陵区典型区域—沂源县为研究区,系统采集427个表层土壤样品(0~20 cm),测定了As、Cd、Co、Cr、Cu、Mn、Ni、Pb、Hg和Zn共10种重金属含量;采用多元统计分析和地统计分析方法,揭示了土壤重金属的主要来源;进一步分析得出研究区重金属的空间分布以及与成土母质、工业排放和农业生产污染之间的关系。研究表明:1)沂源县表层土壤中10种重金属元素的平均含量值均高于土壤背景值但未超过国家二级土壤元素限定值,存在一定程度的重金属富集。2)经主成分分析和单因素方差分析后将研究区重金属的来源主要分为3类:As、Co、Cu和Mn主要来源于成土母质,属自然源因子;Hg、Cd、Zn和Pb受到母质和工农业污染双重控制,属于混合来源;Cr和Ni主要是成土母质影响下的自然来源。3)自然来源重金属含量的高值区主要与石灰岩成土母质类型分布相一致,Hg、Cd、Zn和Pb元素含量的高值区与工业区分布基本一致。4)通过潜在生态风险评价,沂源县表层土壤目前处于中度潜在生态风险等级,其中Hg和Cd潜在生态风险最强,达到中度生态危害,其他元素具有轻微的潜在生态危害。研究中通过多元统计-地统计模拟分析法有效的揭示了土壤重金属污染源汇特征,可作为评估该区土壤污染现状和对土壤重金属污染进行风险评价的重要依据。

Source spatial distribution and risk assessment of heavy metals in Yiyuan county of Shandong province

Abstract: Mountainous and hilly regions are important part of agricultural production regions, where massive heavy metals continuously accumulate in soils due to anthropogenic inputs. Soil contamination will threaten human health when it is brought into agricultural production, so accurate assessment of soil heavy metal contamination is crucial for building high standard arable land and ensuring food safety. In this paper, Yiyuan County, Shandong Province was selected as the study area about typical mountain county. The contents of heavy metals of As, Cd, Co, Cr, Cu, Ni, Pb, Hg, Zn and Mn were determined from 427 surface soil samples (0-20 cm). The multivariate statistical analysis, including principal component analysis and one-way analysis of variance (ANOVA) analysis, and geostatistical analysis were used to evaluate the pollution characteristics on the heavy metals in soils that were affected by the natural parent materials and human activities. The results show: 1) The average contents of As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Zn and Mn were 9.08, 0.15, 15.32, 73.54, 33.84, 0.04, 33.64, 34.92, 84.72 and 668.17 mg/kg, respectively, and these values were slightly higher than natural background values, but did not exceed the values of national secondary soil standard, which revealed the slight level of heavy metals enrichment that would not endanger the human health. 2) The sources of heavy metals were mainly classified into 3 categories through principal component analysis: As, Co, Cu and Mn, which belonged to PC1, originated from natural parent material and belonging to natural source; Hg, Cd, Zn and Pb, classified into PC2, mainly controlled by soil parent material and industrial and agricultural pollution; Cr and Ni were regarded as natural factor under the influence of natural parent materials. The one-way ANOVA analysis further validated the source of hazardous elements in soils. Heavy metal content was significantly different among different types of land use in this region, especially Hg, Pb and Zn values had the most obvious difference in urban construction land, and their accumulation rates were 141.3%, 74.1% and 69.4% higher than natural background values, respectively, suggesting that the land had been affected by industrial production activities. The other elements mainly belonged to natural sources and they were not significantly different among land use types. 3) The high-value areas of heavy metals with natural sources were mainly consistent with the parental material of limestone. The high-value areas of heavy metals with anthropogenic input were basically the same as the distribution of industrial areas. 4) Through the evaluation of potential ecological risk index in the study area, the index values of As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Zn were 14.42, 40.92, 6.96, 2.62, 8.63, 60.88, 1.21, 7.16, 6.87 and 1.51, respectively. The values of these elements suggested only a slight ecological risk in Yiyuan County, except Hg and Cd with moderate potential ecological risk level. risk index (RI) in Yiyuan County was 151.8, which was currently at a moderate ecological potential risk level. The multivariate statistics - geostatistical simulation analysis method established in the research effectively reveals the characteristics of the source-sink of heavy metal contamination in soils, which can be used as an important basis for assessing the status of soil pollution and is vital in controlling heavy metal pollution in soil for the mountainous and hilly areas.