典型石漠化峰丛洼地土壤重金属的空间分异特征及其影响因素

研究石漠化峰丛洼地土壤重金属空间分异特征及其影响因素, 对推动区域土壤重金属污染防治、石漠化综合治理具有重要的指导意义和实践价值。以广西平果市典型石漠化峰丛洼地土壤为研究对象, 通过调查采样分析以及综合运用地统计学、地质累积指数、潜在生态危害指数和地理探测器等方法, 分析探讨土壤重金属的空间分异特征及其影响因素。结果表明, 研究区8种重金属元素的空间分布总体呈东北向西南降低的变化格局, 研究区东北部和东南部为重金属高值叠加区的集中分布区, Cr，Cd元素呈现中等的空间相关性, 其他6个重金属元素表现为强空间相关性；研究区受Cd，As，Cr，Cu，Zn等元素不同污染程度的影响, 且以Cd的影响尤为突出, 其地质累积指数和潜在生态危害指数分别高达1.34和107.73；pH、地层、Fe₂O₃、土地利用、P、CaO、Mn、到断层距离、石漠化程度是影响研究区土壤重金属空间分异的主要因子, 而且不同因子组对土壤重金属空间分异的交互作用以双因子增强型和非线性增强为主。因此认为不同因子对石漠化峰丛洼地土壤不同重金属元素空间分异特征的影响程度存在差异, Cd是石漠化峰丛洼地土壤污染程度和潜在生态危害程度最严重的重金属元素, 地层、Mn、CaO、岩性、到断层距离、P是影响Cd空间分异的关键因子。 

Spatial variations and influencing factors analysis of heavy metals in the soil of typical rocky desertification peak cluster depression

Karst peak cluster depression areas are characterized by a special double-layer hydrogeological structure, and under the influence of human activities, there are many environmental problems, such as soil erosion, rocky desertification, dryness and wetness, and heavy metal pollution. How to clarify the spatial variations and influencing factor analysis of heavy metals in the soil of typical rocky desertification peak cluster depressions has become an important content to promote the prevention and control of heavy metal pollution in soil and the comprehensive management of rocky desertification. The typical rocky desertification peak cluster depression soil in Pingguo City, Guangxi, was selected as the research object in this study.Spatial variations, associated mechanisms and pollution risk assessments of eight heavy metals (e.g., As, Hg, Cr, Ni, Cu, Zn, Cd, and Pb) in soil were carried out by using the geo-statistical, geological accumulation index, potential ecological danger index and geographical detector methods. These results show that the spatial distribution of heavy metals in the study area generally shows a downward trend from northeast to southwest. Cr and Cd show medium spatial correlation, and the other six heavy metals show strong spatial correlation, which was analyzed by semivariogram. The study area is affected by different pollution levels of Cd, As, Cr, Cu and Zn, and the impact of Cd is the most important. The geological accumulation index and potential ecological hazard index of Cd are 1.34 and 107.73, respectively, but the average geological accumulation index of other heavy metals is less than 0, and the potential ecological hazard index is less than 16.The main factors affecting the spatial differentiation of eight heavy metals in the soil of the study area are pH, stratum, Fe₂O₃, land use, phosphorus, CaO, Mn, distance to fault and rocky desertification degree. Moreover, the interaction types of different factor groups on the spatial differentiation of heavy metals in soil were mainly two factors enhanced and nonlinear enhanced. Therefore, it is considered that different factors have different effects on the spatial differentiation characteristics of various heavy metals in the soil of rocky desertification peak cluster depression. Cd is the most serious heavy metal element in the soil pollution degree and potential ecological harm degree of rocky desertification peak cluster depression. Strata, Mn, CaO, lithology, distance to fault and phosphorus are the key factors affecting the spatial differentiation of Cd.