柴达木盆地南部大气降尘重金属来源及其生态风险评估OA

As the"Treasure Basin"in the Qinghai-Xizang Plateau,the Qaidam Basin is rich in critical mineral resources,and is the region where human activities are concentrated.Because of the long-term resource exploitation,the ecological fragility is intensifying and the atmospheric pollution is worsening.Thus,the distribution and environmental risk of the heavy metals in atmospheric dust should be systematically studied.This study collected dust-fall samples from six monitoring sites along the southern Qaidam basin monthly from 2020 to 2023.These dust-fall samples had been classified as rural and urban,each during heating and non-heating periods.The concentration and spatiotemporal patterns of metal elements(Fe,Al,Ti,Cr,Cd,Cu,Mn,Ni,Pb,V,Zn)had been analyzed.Based on the enrichment factors,geo-accumulation indices,ecological risk indices,and health risk evaluation models,the pollution level and risk of heavy metals had been evaluated,and the source of the heavy metals had been identified by the Positive Matrix Factorization(PMF).The result showed that the atmospheric dusty heavy metal concentration in the southern Qaidam Basin was obviously lower than in other regions of China,indicating the weak influence of human activities in the study area.Except for Ti,the concentration and enrichment factors of other heavy metals in urban were higher than in rural area,with no obvious seasonal variation.PMF analysis revealed that soil dust was the primary source of atmospheric dust during both heating and non-heating periods,indicating limited anthropogenic influence.Vehicular emissions were the secondary source,with significantly greater contributions in urban areas.Risk assessment indicated that Cd and Zn posed moderate ecological risks;Cr,Pb,and Zn also threatened human health,especially inhalation of Cr,which might present carcinogenic risks to adults.Currently,these pollutants had not caused substantial ecological or health impacts locally.