Characteristics And Source Analysis Of Chemical Components Of Atmospheric PM_2.5 In Urumqi

Atmospheric particulate matter is the core pollutant that causes air pollution.Among them,water-soluble ions,heavy metal elements and poly cyclic aromatic hydrocarbons also have multiple effects on human health.The study on the concentration and composition characteristics of particulate matter has important theoretical references for the treatment of air pollution.In this paper,particulate matter sampling was carried out in Urumqi,and the chemical components were studied,and the following conclusions were drawn:（1）The PM_2.5 mass concentration before heating was higher than that after heating,and the industrial area and traffic area had a favorable influence on the generation of PM_2.5.During the sampling period,PM_2.5 was negatively correlated with temperature and O₃,and positively correlated with humidity.The results of backward trajectory cluster analysis show that the largest air mass in Urumqi during the sampling period is the local southeast air flow from Xinjiang.（2）The mass concentration of total water-soluble ions in PM_2.5 at various points in Urumqi in descending order is:Midongqu>Xinjiang Agricultural University>Xiaoximen>Santunbei where the content of SO₄^2-,NH₄⁺,NO₃^-and Cl^-is higher.The secondary ions in the atmosphere mainly exist in the form of（NH₄）₂SO₄,NH₄HSO₄,NH₄NO₃ and NH₄Cl.The results of multiple source analysis show that the main sources of water-soluble ions in air PM_2.5 in Urumqi are secondary conversion and wind-blown dust.（3）The mass concentration of Fe element in PM_2.5 in Urumqi was the highest.The enrichment factor index showed that the elements were mainly from anthropogenic sources,and the element with the most obvious enrichment was As.The results of geoaccumulation index show that Mn is non-polluted,while Fe,As,Cu,Hg,Pb,Zn and Ni are all polluted to different degrees.The running PMF model shows that the emissions from industrial activities and fuel oil are the main sources of elements.（4）During the sampling period,the monomer PAHs with the highest mass concentration was Flur,and the lowest content was Ant,which showed that the content of high-cyclic molecules in PM_2.5 was greater than the content of low-cyclic molecules in PM_2.5.The results of three source analysis showed that the PAHs in the air PM_2.5 in Urumqi were mainly from motor vehicles.（5）The potential risk evaluation of elements shows that the risk values of Mn and Ni elements are lower,while the risk values of Fe,As,Cu,Hg,Pb and Zn elements are higher.The health risk assessment of human body showed that there was no non-carcinogenic risk of non-carcinogenic elements for different groups of people.The carcinogenic element Ni has no carcinogenic risk to human,while As has potential carcinogenic risk to human.The results of human health risk assessment of PAHs showed that the carcinogenic risk values of PAHs in PM_2.5were all lower than carcinogenic levels for different populations.