Pollution Characteristics,Source And Health Risks Of Elements Bonded With Atmospheric PM_2.5 And PM₁₀ In Linyi City

The industrialization and urbanization in Linyi city has accelerated in recent years,resulting in serious atmospheric environmental problems dominated by PM_2.5and PM₁₀.PM-bonded hamful elements could enter the body mainly through the inhalation pathway to circulate in the blood,endangering human health.However,the current research on the elements bonded with particulate matter in Linyi is very limited.Therefore,the PM_2.5 and PM₁₀ samples collection was carried out simultaneously in Linyi from December 2016 to October 2017.The seasonal variation and size distribution characteristics of the elements were analyzed.Combined with various research methods such as enrichment factors,positive matrix factorization（PMF）and backward trajectory model,the emission sources of elements in particles were further judged and identified.On this basis,the health risk assessment model was used to calculate the risks of heavy metals under inhalation pathway for different exposed populations,the results indicated that:（1）The total mass concentrations of detected elements in PM_2.5 and PM₁₀ were9.79μg/m³ and 22.00μg/m³,respectively,and Si was the most abundant element in the area.In the non-crustal elements,Zn presented the highest concentration.Most elements（except Ti,Ni,Mo,Cd and Mg）exhibited highest concentrations in winter or spring and the lowest in summer.Si,Al,Ca and Na showed the highest levels in spring,due to the influence of sand suspension in springtime;Cu,Zn,Pb and Sb showed the highest levels in winter,ascribing to increased emissions of coal burning for heating.（2）The PMF results presented that the fugitive dust（41.22%）and the mixed source of coal and copper smelting（22.64%）were the main sources of elements in PM_2.5,followed by vehicle（14.71%）and industrial emissions（13.94%）,the municipal waste incineration（7.49%）contributed the least.The primary source of elements in PM₁₀ was the fugitive dust（55.47%）,followed by the coal-fired mixed source（19.80%）,motor vehicle emissions（7.48%）and industrial sources（12.83%）.Combined with backward trajectory clustering and Potential Source Contribution Factor（PSCF）,it was found that the airflow from northwest and southwest with short transmission distance accounted for the highest proportion of the total trajectory,which were 27.82%and 21.37%,respectively;the junction area of Shandong,Henan,Anhui and Jiangsu was the main potential source area of PM_2.5and heavy metals were mainly affected by southern Shandong,northern Anhui（Huai Bei）and northwestern Jiangsu（Xu Zhou）.（3）The non-carcinogenic risks of V,Cr,Co,Ni,Zn,As,Cd and Pb bonded with PM_2.5 and PM₁₀ in atmosphere in Linyi could be ignored.However,Cr,Co,Ni,As and Cd had the highest carcinogenic risks for the elder,followed by adults and youth,and lowest for children.The cancer risks caused by Co,Ni,As and Cd were within the acceptable range for four age groups,while Cr had carcinogenic risks for adults and the elder.（4）The sources of elements bonded with PM_2.5 and PM₁₀ had no non-carcinogenic risks for exposure population.Coal-fired mixed sources and industrial emissions had the highest cancer risks and lowest for fugitive dust.Industrial emission for elements in PM₁₀ had carcinogenic hazards for the elder,which was mostly related to the high contribution of Cr produced steel and iron plants.