银川市黄河滩区土壤重金属污染特征、生态风险评价与来源解析

为了解银川市黄河滩区土壤重金属污染现状及来源,采用电感耦合等离子体质谱法（ICP-MS）测定了银川市黄河滩区共92个采样点土壤样品中Zn、Cu、Cr、Pb、Ni、Cd、As和Mn这8种重金属的含量,采用富集因子、地累积指数法与潜在生态风险指数法对重金属污染特征进行分析和评价,并结合相关性分析、绝对主成分-多元线性回归受体模型（APCS-MLR）、正定矩阵因子分解（PMF）模型和地统计学对土壤重金属进行来源解析.结果表明,Cu和Pb含量平均值低于银川市土壤背景值,Zn、Cr、Ni、Cd、As和Mn含量平均值分别是背景值的1.28、1.06、1.08、1.79、1.11和1.19倍,所测8种重金属元素含量平均值均低于农用地土壤污染风险筛选值；不同用地类型之间重金属含量平均值表现为：荒地>退耕地>林地>耕地；研究区Zn和Cd呈轻微富集,其余6种元素无富集；Cd属于中度潜在生态风险水平,其余重金属处于轻度水平；联合受体模型表明交通和农业等人为活动来源对Zn和Cd的贡献较大,其余重金属受土壤母质等自然源影响较大.研究结果可为银川市黄河生态保护与可持续发展提供科学依据.

Characteristics, Ecological Risk Assessment, and Source Apportionment of Soil Heavy Metals in the Yellow River Floodplain of Yinchuan City

In order to study the status and sources of heavy metal pollution in Yinchuan Yellow River floodplain soils, we used inductively coupled plasma mass spectrometry (ICP-MS) to determine the presence of eight heavy metals in 92 soil samples from the Yinchuan Yellow River floodplain and used enrichment factors, geological accumulation index, and potential ecological risk index to analyze and evaluate the characteristics of heavy metal pollution in the study area. Combined correlation analysis, absolute factor analysis-multiple linear regression model (APCS-MLR), positive matrix factorization (PMF), and geostatistics were used to analyze the sources of soil heavy metals. The results showed that the content of eight heavy metals in the surface soil of the Yellow River floodplain in Yinchuan City were lower than the screening value of soil pollution risk in agricultural land; Cu and Pb contents were lower than the background value of Yinchuan City soil, and the contents of the remaining six elements were higher than the background value. The coefficients of variation of Zn and Cd were large and in the medium variation level and were influenced by anthropogenic activities. The heavy metal content varied between different land types and generally showed that wasteland > abandoned farmland > woodland > cultivated land. The average content of Cu and Pb in forest and arable soils was lower than the regional background value, whereas the rest of the heavy metals in different land types were higher than the soil background value. The analysis of enrichment factors showed that Zn and Cd were slightly enriched in the study area, and the cumulative index method and the evaluation of the potential risk of single heavy metals indicated that more than 60% of the sites in the study area were contaminated with Cd at a medium or higher potential ecological hazard. The comprehensive evaluation results of potential ecological risk showed that the overall ecological risk level of the study area was mild. From the distribution of heavy metal ecological risk comprehensive index sample points, only one point was in moderate ecological hazard, and the pollution point showed very few. Comprehensive correlation analysis, APCS-MLR model, PMF model, and geostatistical analysis results confirmed that Zn and Cd in the study area were mainly derived from human activities such as agricultural activities and transportation, and the remaining heavy metals were derived from soil parent materials. The results of this study can provide a scientific basis for the ecological protection and sustainable development of the Yellow River in Yinchuan City.