秦王川盆地土壤重金属来源、分布及污染评价

为探究秦王川盆地土壤重金属的来源、分布及污染情况，测定了研究区51个表层土壤样品的8种重金属（Cr、Zn、Cu、As、Pb、Mn、Ni、Cd）总量和pH值；采用多元统计、地质统计方法和GIS技术对重金属的来源、空间变异结构和分布进行了研究，利用污染指数法和模糊综合评判法对重金属污染进行了评价.结果表明：Zn、Ni含量均值大于当地背景值，其余重金属含量均值都低于背景值；Cd属于强变异，其余均为中等变异，Zn、Cr服从对数正态分布，其余均服从正态分布；Cr、Cu、As、Pb、Mn主要为成土母质等自然来源，Cd、Ni主要来源于工业、交通污染，Zn主要来源于农业生产；Zn、As、Ni、Cd的空间分布呈岛状，Cu、Mn呈带状分布，Cr、Pb呈岛状和带状分布相结合的特点；污染指数评价结果为Cr、Cu、Pb处在警戒线，As、Mn、Ni属于轻度污染，Cd为中度污染，Zn为重度污染；模糊综合评判得出1个土样为轻度污染，2个为警戒程度，其余为安全；土壤质量标准是反映土壤质量的依据，总体看，研究区土壤重金属环境质量良好，均未超过国家土壤环境质量二级标准.

Source analysis,distribution and pollution assessment of the soil heavy metals in the Qinwangchuan Basin

The total contents of eight soil heavy metals (Cr, Zn, Cu, As, Pb, Mn, Ni, Cd) and pH of 51surface soil samples in the study area were measured to explore the source, distribution and pollution degree of the soil heavy metals in the Qinwangchuan Basin. The multivariate statistics, geostatistical methods and GIS technique were used to investigate the sources, spatial variability and distribution of soil heavy metals, while the pollution index and fuzzy comprehensive evaluation methods were applied to evaluate the soil heavy metal pollution. Results indicate that the average concentrations of Zn and Ni were greater than the local background values, while the others were lower than the background values. The variability of Cd was significant, whereas others were medium; the concentrations of Zn and Cr conformed to lognormal distribution, and the rest followed the normal distribution; Cr, Cu, As, Pb and Mn were the natural sources of soil matrix, Cd and Ni were mainly sourced from industrial and traffic pollution, while Zn was mainly sourced from agricultural production activities. The concentration profiles of Zn, As, Ni and Cd were island-like, and the Cu and Mn were banded, while the Cr and Pb are the mixed pattern of island-like and band-like. The the pollution index evaluation results show that Cr, Cu and Pb were on alert, As, Mn and Ni were lightly polluted, Cd was moderately polluted, and Zn was highly polluted. Fuzzy comprehensive evaluation showed that only one soil sample was mildly contaminated and two were in alert level, and the rest were within the safety scope. The soil environmental quality standards were the basis for soil quality evaluation. It can be observed that the soil quality of all the samples were within the national secondary standards and the environmental quality of soil heavy metal in the study area was generally good.