宁夏中部干旱带农田土壤重金属污染特征及来源解析OA

Soil is a fundamental resource for agricultural production,and the spatial distribution and pollution levels of soil heavy metals are critical to farmland ecosystems and human health.To characterize heavy metals and metalloid contamination and its drivers in farmland soils of the central arid zone of Ningxia,it conducted soil sampling for three consecutive years(2021-2023),analyzed the spatial distribution and correlations of heavy metals and metalloid contents,evaluated contamination status and ecological risk,and apportioned pollution sources.The mean concentrations of Pb,As,Zn,Ni,Cu,Hg,Cr and Cd were 26.47,9.52,58.51,33.80,22.60,0.04,48.00 and 0.16 mg·kg—1,respectively.Relative to Ningxia'a natural soil background values,these metals showed varying degrees of enrichment but did not reach high pollution levels,and none exceeded the the risk control values specified in the Soil Environmental Quality—Risk Control Standard for Soil Contamination of Agricultural Land(GB 15618-2018).this indicates that heavy metal contamination of farmland soils in the study area is generally low and overall soil environmental quality is good.Ecological risk assessment identified Hg as the principal risk contributor,with some sites exhibiting moderate to relatively high risk;however,all remained within the risk control thresholds for agricultural soils.Correlation analysis combined with positive matrix factorization(PMF)resolved four major sources of heavy metals:traffic-related emissions(24.01%),natural background(35.43%),agricultural production activities(24.46%),and industrial/medical anthropogenic emissions(16.10%).These results show that anthropogenic activities contribute substantially to heavy metal inputs and their transport and transformation,underscoring the need for continued attention and strengthened management of agricultural,industrial,and transportation-related sources.