| Urumqi city is one of the most seriously air-polluted cities in China and even in the world,where the pollution is severer during the heating period.The spatial-temporal variation characteristics and sources of heavy metals in PM10 and PM2.5 in Urumqi are analyzed in this paper in order to lay a scientific basis for the control measures.With PM2.5/PM10 portable sampler,the PM10 and PM2.5 atmospheric samples were collected from five functional areas in Urumqi city.The results show that during the whole sampling period the annual variation of atmospheric PM10 and PM2.5 in Urumqi city is obvious with extremely significant seasonal difference.The overall trend shows that winter＞autumn＞spring＞summer.It is most polluted in Kaziwan Cement Works during the whole sampling period and the mass concentrations of PM10 and PM2.5 both exceed the standard range.PM10 and PM2.5 pollutions exist to different extent at the rest of sampling points. The pollution level during the heating period of autumn and winter is much higher than that during non-heating period in summer and spring.The correlation between the variation trend of PM10/PM2.5 and SO2 is significant,which indicates that PM10 and PM2.5 are significantly affected by heating.The contents of five elements Cd,Cu,Ni,Pb and Mn were inspected with TAS-990 graphite-oven atomic absorption spectrometer,It is shown that the atmospheric heavy metals in Urumqi City are more likely enriched on PM2.5,i.e.the smaller particle.The average concentration of heavy metals in atmospheric PM10 and PM2.5 varies in different seasons.Of which,the average concentrations of Pb,Cu,Cd and Mn during heating period are higher than those during non-heating period,but the average concentrations of Ni during non-heating season is higher than heating season.Kaziwan Cement Works is the area where the average concentrations of Pb,Cd and Mn in PM10,PM2.5 are the highest.Cu and Ni in PM10 are higher in the living quarter of Xinjiang Agricultural University,in addition to the highest average mass concentration of Cu in PM2.5;the highest average mass concentration of Ni in PM2.5 is located on Youhao Road.The enrichment factors of four heavy metals Pb,Ni,Cu and Cd in atmospheric PM10 and PM2.5 exceed 10 mostly,and relate to anthropic activities,mainly from industrial coal,emissions during the heating period,metal smelting,machine manufacturing,traffic and transportation etc.also from the crustal material (such as soil dust).The enrichment factor of Mn is less than 10,which indicates that Mn comes mainly from earth's crust.
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