基于GIS和受体模型的枸杞地土壤重金属空间分布特征及来源解析

通过测定"万亩枸杞示范园"119个表层(0～20 cm)土壤样品中重金属铅(Pb)、镍(Ni)、锌(Zn)、锰(Mn)、铜(Cu)、铬(Cr)和镉(Cd)含量,以宁夏土壤背景值为评价标准,利用单因子指数、内梅罗综合指数和潜在生态危险指数评价土壤重金属污染状况,借助绝对因子分析/多元线性回归受体模型(APCS-MLR)与地统计相结合的方法,对土壤重金属空间分布及来源进行分析.结果表明,Pb、Ni、Zn、Mn、Cu、Cr和Cd含量分别为34. 78、52. 376、83. 692、641. 114、38. 130、87. 257和0. 149 mg·kg~(-1),均低于国家土壤污染风险筛选值但超过了宁夏土壤背景值.内梅罗综合指数显示枸杞地81. 51%样点的土壤重金属呈现轻度污染,16. 81%样点呈现中度污染,1. 68%未受重金属污染.潜在生态危险复合指数表明,13. 45%样点表现为轻微生态风险,86. 55%样点表现为中等生态风险.枸杞地土壤重金属有4种主要来源:自然源、工业活动源、交通源和农业活动源,其中Ni和Cr的来源以自然源为主,贡献率分别为55. 49%和64. 66%,Pb和Mn的来源以工业活动源为主,贡献率分别为46. 93%和42. 53%,Zn和Cu的来源以交通源为主,贡献率分别为43. 51%和53. 71%,Cd的来源以农业活动源为主,贡献率为76. 79%.枸杞地土壤重金属含量明显受人类活动影响且来源复杂,应根据其贡献率加强控制,确保中宁枸杞土壤资源的可持续利用.

Spatial Distribution Characteristics and Source Apportionment of Soil Heavy Metals in Chinese Wolfberry Land Based on GIS and the Receptor Model

A total of 119 surface soil samples (depth of 0-20 cm) were collected from a Chinese wolfberry demonstration garden in Zhongning of Ningxia, and samples were analyzed for seven heavy metals (Pb, Ni, Zn, Mn, Cu, Cr, and Cd). The single factor index, comprehensive index, and potential ecological risk were used to assess the soil heavy metal contamination with the soil background values of Ningxia as the evaluation standards. The absolute principal component scores and multivariate linear regression (APCS-MLR) model as well as geostatistic analysis were combined to identify and apportion the pollution sources of soil heavy metals. The results showed that the average concentrations of Pb, Ni, Zn, Mn, Cu, Cr, and Cd in soils were 34.78, 52.376, 83.692, 641.114, 38.130, 87.257, and 0.149 mg·kg^-1, respectively. The mean concentrations of heavy metals were higher than the local soil background values but lower than the risk screening values for soil contamination of agricultural land. The comprehensive index results showed that the pollution degree of soil heavy metals was at the slightly polluted level in 81.51% of the samples, at the moderately polluted level in 16.81% of the samples, and at the unpolluted level in 1.68% of the samples. The comprehensive index values for potential ecological hazards were less than 60 in 13.45% of the samples, and these values were associated with a slight potential for ecological risks. The comprehensive index values for potential ecological hazards were less than 120 and more than 60 in 86.55% of the samples, and these values were associated with a moderate potential for ecological risks. The four main pollution sources of soil heavy metals in the study area included natural sources, industrial activity, traffic, and agricultural activity. Natural sources were the main source of Ni and Cr with average contribution rates of 55.49% and 64.66%, respectively. Industrial activity was the main source of Pb and Mn with average contribution rates of 46.93% and 42.53%, respectively. Traffic was the main source of Zn and Cu with average contribution rates of 43.51% and 53.71%, respectively. Agricultural activity was the main source of Cd with an average contribution rate of 76.79%. The study results indicated that soil heavy metals have tended to concentrate in the Chinese wolfberry demonstration garden, and the sources of heavy metals were complex and obviously influenced by human activities. Controls should be strengthened for sources that contribute to soil heavy metals to ensure the sustainable utilization of soil resources in the Chinese wolfberry land.