Characteristic Analysis And Health Risk Assessment Of Heavy Metal Pollution In PM_2.5 Of Taiyuan City And Surrounding Ambient Air

With the rapid growth of the world economy and population,a series ofsocial environmental air pollution problems have accompanied the widespread concern of the society.PM_2.5has the characteristics of small particle size and large specific surface area.It can be used as a carrier for a variety of pollutants.The heavy metal components it carries can cause great harm to the human body.Therefore,in recent years,research on heavy metal components in PM_2.5Gradually increase.Therefore,it is particularly critical to analyze the pollution characteristics and source analysis of heavy metals in PM_2.5with the help of chemical analysis and pollutant receptor models.At the same time,the use of health risk assessment models to conduct risk assessments of people in specific areas is helpful to clarify the Exposure risk.In this study,in 2017 and 2018,a total of 42 PM_2.5samples were collected in Taiyuan and Yuci University Town,and the collected samples were analyzed by ICP-MS to obtain 10 elements（arsenic,cadmium,cobalt,chromium,copper,manganese,nickel,lead,vanadium and zinc）.By analyzing the concentration and spatial and temporal distribution of heavy metals in PM_2.5at two points,combined with the characteristics of local heavy metal pollution sources,the receptor model and health risk model were used for analysis and evaluation.The main conclusions obtained are as follows:（1）Manganese,lead,and zinc are the three elements with the highest concentration among the heavy metal components of PM_2.5in Taiyuan City,with average values of 114.27±78.36ng/m³,73.41±57.58ng/m³,and 195.54±128.98ng/m³.The total concentration accounted for 79.90%and 85.45%of the total heating and non-heating season concentrations,respectively.Manganese,lead and zinc are the three elements with the highest concentration in the heavy metal components of PM_2.5in Yuci University Town,with average values of 56.57±32.95ng/m³,70.02±56.66ng/m³and 201.23±164.71ng/m³,The total concentration accounts for 78.14%and 73.70%of the total heating and non-heating season concentrations,respectively.The lead and cadmium elements in the two sampling points exceeded the national reference limit in both heating and non-heating seasons.The pollution levels of heavy metals in Taiyuan City and Yuci University Town in the non-heating season are similar to the average annual values in other regions,and the concentrations in the two areas during the heating season are significantly higher.（2）The analysis of enrichment factors shows that the 10 elements are mainly affected by anthropogenic sources.The levels of heavy metal enrichment in Taiyuan City and Yuci University Town are:zinc,lead and cadmium are significantly enriched（92.25-476.71）,vanadium,nickel and chromium,Arsenic and copper are moderately enriched（10.74-40.93）,cobalt and manganese are slightly enriched（1.17-6.91）.The Cd element is the most enriched element,which is most affected by anthropogenic sources.The concentration of heavy metals in the heating season is significantly higher than that in the non-heating season.Coal-fired heating is one of the artificial sources that cause the accumulation of heavy metals in PM_2.5.（3）The main component analysis results of Taiyuan and Yuci University Town are similar,and three main component factors are extracted,which represent dust,metal smelting emissions and industrial dust.The cumulative variance of the non-heating seasons in the two regions is higher than that in the heating season,and the reliability of the analysis results of pollution sources in the non-heating season is higher than that in the heating season.（4）Correlation analysis and PMF analysis results show that coal combustion,industrial processes,motor vehicle exhaust and dust are the main sources of pollution in Taiyuan and Yuci University Town,and the contribution rate of coal burning in the heating season is 38.4%and 40.5%respectively The contribution rate of motor vehicles during the non-heating season is relatively high,at 15.6%and 39.3%respectively..（5）Health risk assessment shows that manganese in PM_2.5in Taiyuan and Yuci University Town can cause a strong non-carcinogenic risk,and the non-carcinogenic risks caused by heavy metal elements other than manganese are much lower than the US Environmental Protection Agency（EPA）The limit,the non-carcinogenic risk coefficient is between 1.02×10^-5-5.23×10^-1.People in the heating season have a higher non-carcinogenic risk than non-heating seasons,and children have a higher non-carcinogenic risk than adults.Compared with the carcinogenic risks of Taiyuan City and Yuci University Town,the two have similar descending laws.The carcinogenic risks of chromium and arsenic in PM_2.5in Taiyuan and Yuci University Town are higher than the EPA threshold,and the population is susceptible to these two.Carcinogenic effects caused by various elements.The results of the study are devoted to explaining the effects and hazards of specific pollution sources on people’s health,and help to implement preventive and control measures.In summary,there are differences in the levels of heavy metal pollution and types of pollution sources in PM_2.5in Taiyuan and Yuci University Town,resulting in different health exposure risks.In the prevention and control of air pollution,comprehensive management can be carried out in accordance with the types of local industrial enterprises and the types of pollution sources.