Characteristics,sources and health risk assessment of heavy metal and metalloid pollution in atmospheric PM2.5 in Hohhot City,2021
Objective To understand the pollution characteristics and main sources of heavy metals and metalloids in atmospheric PM2.5 in Hohhot City,and to evaluate their health hazards.Methods Atmospheric PM2.5 sampling was conducted monthly in the urban area of Hohhot City in 2021,and the characteristics and changing rules of mass concentration were analyzed.The sources of 12 metals and metalloids were analyzed through principal component analysis.The U.S.Environmental Protection Agency's health risk assessment model was applied to performing a health risk assessment of 9 pollutants.Results Among the 146 samples collected,41,2,1 and 7 samples exceeded the standard limits for PM2.5,As,Ni and Mn respectively.Cr in 103(70.55％)samples exceeded the standard limit,with an actual exceeding limit of 7.4 times.The main sources of heavy metals and metalloids in PM2.5 included coal-fired sources,transportation sources,steel and metallurgical industry sources and crustal sources.The level of non-carcinogenic health risk was relatively low.Both As and Cr had carcinogenic risks ranging from 10-6 to 10-4,indicating potential carcinogenic risks.Conclusion The mass concentrations of atmospheric PM2.5 and its heavy metals and metalloids in Hohhot City are higher during the heating period,and the main sources of heavy metals and metalloids in atmospheric PM2.5 are compound sources.Hence it is necessary to strengthen control measures in various aspects.Adults'health risk increases with the increasing age,and the health risk levels of the elderly aged above 60 years and children are higher.
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