Characteristics,Sources and Health Risk Assessment of PM2.5-bound Metal Elements in Dalian
To study the pollution characteristics and health risks of heavy metals in PM2.5 in Dalian,a total of 120 effective samples were collected from June 3,2021 to May 29,2022,once every 3 days.The concentrations of 14 heavy metals(Ba,Cd,Sn,V,Cr,Mn,Co,Ni,Cu,Zn,As,Se,Pb and Sb)in PM2.5 were determined by inductively coupled plasma mass spectrometer(ICP-MS).The sources of heavy metal elements in PM2.5 were analyzed by posi-tive matrix factorization(PMF),and the health risk of heavy metal elements was evaluated.The results showed that the concentrations of PM2.5 in Dalian ranged from 4.2 to 159.3 μg·m-3 during the sampling period,with the annual average of(33.2±28.9)μg·m-3.A total of 14 heavy metal elements except Sn were detected in PM2.5.The total mass concentrations were from 0.004 to 0.586 μg·m-3 with an average concentration of(0.139±0.116)μg·m-3.Among all metals,Zn was the most abundant element in PM2.5,with an average of(33.6±23.5)％.The source analysis results showed that the main sources of heavy metals in PM2.5 in Dalian were in order from high to low:industrial process source(41.9％)＞traffic emission source(32.3％)＞coal combustion source(14.4％)＞iron and steel smelting source(11.4％).During the pollution period,the proportion of industrial process sources and coal combustion sources increased.The results of health risk assessment showed that the 12 heavy metals(Cr,Cd,Co,Ni,As,Pb,Ba,V,Mn,Zn,Cu and Sb)in PM2.5 in Dalian had a low non-carcinogenic risk(HI＜1)through respiratory exposure.The non-carcinogenic risk of heavy metals to children was higher than that to adults.Among the 6 heavy metals evaluated for carcinogenic risk,Cd,Co,Ni and Pb basically had no carcinogenic risk for children and adults(R＜10-6);As and Cr had a certain carcinogenic risk both for children and adults(10-6＜R＜10-4).The cumulative carcinogenic risk of the six heavy metals was the highest for adult males(ILCR=6.51×10-5),followed by adult females(ILCR=5.54×10-5),and the lowest for children(ILCR=1.42×10-5).Pb and As had a certain carcinogenic risk for adults,whereas Cr had a higher carcinogenic risk during periods of PM2.5 pollution.
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