袁州区土壤硒与重金属含量空间关联及其影响因素分析

Spatial correlation and influencing factors of soil selenium and heavy metal content in Yuanzhou district

【目的】探究土壤中Se元素和重金属元素的空间关联及其影响因素。【方法】以袁州区为研究区域,采集162份表层土壤样品,利用地累积指数法对土壤中Cd、Hg、As、Pb、Cr污染程度进行评价,采用双变量莫兰指数分析Se和重金属空间相关性,并基于地理探测器,选择土壤性质、距离、NDVI、地形等10种因子为自变量,以双变量局部莫兰指数为因变量,探究土壤Se与重金属含量的空间关联及其影响因素。【结果】①研究区土壤样品中Se含量的平均值为0.5,整体处于富硒水平。重金属含量平均值与江西省土壤背景值比值从大到小依次为Cd、Hg、Cr、Pb、As,比值分别为4.20、1.88、1.59、1.29、1.16倍;As、Pb总体处于无污染状态,Hg、Cr整体处于轻度污染状态,Cd整体处于中度污染状态,各重金属含量平均值除Cd外均低于土壤污染风险筛选值;②Se与5种重金属的空间聚类情况存在显著差异,其中,Se与Cd、Hg、Cr 3种重金属存在较强的空间相关性;③通过因子探测发现,全氮(TN)、速效钾(AK)、pH、有机质(SOM)、距水源距离和距铁路距离对Se元素与重金属元素空间聚类情况的解释力最显著;④交互作用探测发现,土壤性质与其他因子交互作用是Se与重金属空间聚类的主导影响因素。【结论】研究结果可为袁州区安全合理利用富硒土壤资源、开展土壤修复、发展富硒农业提供科技支撑。

【Objective】The present paper aimed to explore the spatial correlation and influencing factors of Se and heavy metal elements in soil.【Method】Taken Yuanzhou district as the research area,162 topsoil samples were collected,and the soil pollution degree of Cd,Hg,AS,Pb and Cr was evaluated by ground accumulation index method,the spatial correlation between Se and heavy metals was analyzed by bivariate Moran index.Based on the geographic detector,ten factors such as soil property,distance,NDVI and terrain were selected as independent variables,and bivariate local Moran index was used as dependent variable to explore the spatial correlation and influencing factors between Se and heavy metal content in soil.【Result】(i)The average Se content of soil samples in the study area was 0.5,and the whole soil samples were in the selenium rich level.The ratio of the average heavy metal content to the soil background value of Jiangxi province was Cd,Hg,Cr,Pb and As in descending order,and the ratios were 4.20,1.88,1.59,1.29 and 1.16 times,respectively;As and Pb were in a pollution-free state,Hg and Cr were in a mildly polluted state,and Cd was in a moderately polluted state,the average content of all heavy metals except Cd was lower than the screening value of soil pollution risk;(ii)There were significant differences in spatial clustering between Se and 5 heavy metals,among which Se had strong spatial correlation with Cd,Hg and Cr;(iii)Through factor detection,it was found that total nitrogen(TN),available potassium(AK),pH,organic matter(SOM),distance from water source and distance from railway had the most significant explanatory power for spatial clustering of Se and heavy metal elements;(iv)Interaction detection showed that the interaction between soil properties and other factors was the dominant influencing factor for spatial clustering of Se and heavy metal.【Conclusion】The research results can provide scientific and technological support for safe and reasonable utilization of selenium-rich soil resources,soil remediation and selenium-rich agriculture in Yuanzhou district.