| Respirable particulate matter(PM10)is an important air pollutant,and many emphasises have been placed on identifying the sources of PM10.The chemical mass balance model(CMB)has been applied widely in the source apportionment of particulate matter all over the world.However,because of serious collinearity in coal dust,soil dust and vehicle exhaust dust,the multi-conclusion on the source of ambient particle by CMB based on the same group data occurred frequently.In this paper,chemical compositions and carbon isotope of organic carbon(OC),elemental carbon(EC)and total carbon(TC)in PM10 in ambient air and from the main sources in Taiuan were measured.In addition,on the basis of chemical mass balance model(CMB),carbon isotope mass balance(CIMB)model was established,which can discriminate the sources including soil dust,coal dust and vehicle exhaust dust.Finally,source apportionment of PM10 in Taiyuan has been conducted basesd on CIMB.Na、Mg、Al、Si、K、Ca、Fe domimated in all the 19 elements in PM10,accounting for more than 95%of the total elements;the percentage of SO42-in PM10 was significantly higher than that of NO3-and Cl-in every sampling site;TC accounted for 26.35%of PM10,and the content of OC was obviously higher than that of EC.The percentage of the sum of 19 elements in PM10 from main sources in Taiyuan ranged from 4%to 61.77%,and there were obvious differences in the content of elements with the lowest content in vehicle exhaust(4.00%);the content of ions in PM10 was low,ranging from 0.24%to 1.37%,which mainly depended on their forming process;there were much higher contents of TC and OC in PM10 from coal combustion and vehicle exhaust,and TC accounted for 89.87%of PM10 in vehicle exhaust.The values of 81 Coc for PM10 in winter and spring in Taiyuan were-38.5‰～-30.5‰ and-31.4‰～-29.4‰,respectively.Compared with δ13COC,there were minor variations for the values of δ13CEC and δ13CTC.The values of δ13CEC in winter and spring were-23.6‰～-23.4‰ and-23.6‰～-22.0‰,respectively.There were significant differences in the values of δ13COC,δ13CEC and δ13CTC,and 6 δ13CTC lied between δ13COC and δ13CEC.The correlations of δ13COC and δ13CEC were highly significant in winter(R2=0.79,P= 5.33E-6),however,there were no correlation between the two values in spring.It suggested that the main source of OC and EC was the same;however,they came from different sources in spring.Large differences existed in the values of δ13COC,δ13CEC and δ13CTC in PM10 emitted from different sources.513COC,δ13CEc and δ13CTC were-26.5‰,-23.2‰ and-23.6‰ in coal dust,-24.6‰,-14.1‰ and-17.3‰ in soil dust,and 27.7‰,-25.5‰ and-27.0‰ in gasoline car exhaust dust,respectively.Generally,EC,OC and TC can be used as the indicator of carbons in ambient air.Based on the relationships of δ13COC,δ13CEC and δ13CTc between ambient air and sources samples,CIMB model was established and iteration method by introducing relaxing factor was used to solve the system of equations.To sum up,the new source apportionment approach based on carbon isotope(CIMB)promotes the development of the theory of source apportionment,and provides a new method used for identification of various pollutants.Source apportionment of PM10 in Taiyuan was conducted by the CIMB.The results showed that the contribution of coal combustion dust,soil dust,vehicle dust,cement dust,steel dust,sulfate and nitrate were 32%,15%,17%,20%,2%,6%and 5%.The contribution rates of coal combustion dust and soil dust to PM10 calculated by CIMB were slightly higher than those by CMB.However,the results of calculation for vehicle dust by the two models kept the same. |
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