| Taiyuan,the capital city of Shanxi Province,which is a heavily polluted city in China and is one of the most heavily polluted areas in the world.Taiyuan is surrounded on three sides（west,east and north）by high mountains.This location makes it hard for air pollutants to disperse,especially in winter when there is a temperature inversion.Nowadays,the ambient air quality has been improved,but the pollution is still serious in Taiyuan.It is urgent to analyze the elemental concentration in the ambient air and identify the sources of heavy metals in particulate matter.Air sampling was performed in four urban and one rural site in heating season（winter/spring）and non-heating season（summer）from 2002-2004.A total of 26 samples with 118 days sampling time were collected.Total suspended particles（TSP）were sampled on filters（100 L/min during 3-7 days）and analysed by inductively coupled plasma mass spectrometry（ICP-MS）.The enrichment factor（EF）and factor analysis（FA）were used to perform source apportionment.And health risk assessment model was used to evaluate cancer and non-cancer risks of children and adults,men and women,urban and rural residents through inhalation.The results showed that:（1）A total of 66 elements were detected by ICPMS and the mean TSP and PM10 across all sampling sites was 424.81 ±239.35μg/m3 and 252.44±68.36μg/m3,respectively,which were exceed the guided values of air quality.（2）The mean concentrations of Ca was 20389 ng/m3,accounting for 4.80% of the total mass particles.Ca had highest concentrations during all the three sampling periods.The mean concentrations of crust elements such as S,Fe,Si,Al,K,Mg and Na were below the mean concentration level of Ca,accounting for 11.59% of the total mass particles.（3）The heating season had typically 1.5-3 times higher level as compared to summer season.Mean TSP across all sampling sites was 248 μg/m3 in summer and 478 μg/m3 in winter.Average elemental concentrations of S,Pb,Br,Mn,Se,As,Ni,Cd and Hg were higher during the heating season（23.3μg/m3,821 ng/m3,725 ng/m3,460 ng/m3,79 ng/m3,65 ng/m3,34 ng/m3,17 ng/m3 and 3.5 ng/m3,respectively）than the summer（9.6 μg/m3,276 ng/m3,138 ng/m3,283 ng/m3,0 ng/m3,21 ng/m3,21ng/m3,6.8 ng/m3 and 0 ng/m3,respectively）,except for Cr and Co,of which the levels were higher in summer.（4）The EF and FA were used to perform source apportionment.Relatively high EFs suggested that these heavy metals may originate from anthropogenic.Coal burning for heating,vehicles,fugitive dust and electricity production were the main sources.（5）A health risk assessment through inhalation in different people demonstrated that Mn and Cr could have a risk of non-cancer effects（HQ>1）.The HQ values of children and men were higher than adults and women,respectively.There was no difference between urban and rural people.Estimated lifetime cancer risks(Ri>10-6)were observed for As,Cd,Co,Cr and Ni,indicating that cancer risks from air pollution were relatively high in Taiyuan.The Ri values of children and women were below the level of adults and men,respectively.The highest cancer risk was observed for Cr(Ri>10-4).It has been suggested that Taiyuan is a heavily polluted city and atmospheric particulate matter may cause problems on human’s health.There are non-cancer and cancer risks through inhalation for different people.There is an obvious need for further reduce particle emissions and introduce more efficient and cleaner heat and energy production systems in China. |
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