| High ambient concentrations of particulate matter(PM)have been received great concern in China,regarding its potential impact on air quality,global climate and human health.The receptor model of CMB becomes the most important and widely used source apportionment technique,for its simple and clear physical meanings and arithmetic.Chemical source profiles,the "fingerrprints" of emission sources,are usually used as input data for source apportionment of receptor models such as chemical mass balance(CMB)and Positive Matrix Factorization(PMF).The representativeness and collinearity have a far-reaching impact on the performance of CMB.Hundreds of original(derived from measured results)and composite(merging different source profiles of subcategories)profiles have been collected in the research group.Related source categories include coal-fired boiler,vehicle exhaust,fugitive dust and so on.Data quality control were applied to create high quality composite profiles of each source category.Chemical composition of these profiles are analyzed.Statistical measures of correlation coefficient,t-test and and distribution of weighted differences are used to compare the similarities and differences among individual and composite profiles.In addition,numerical simulation was applied to estimate the uncertainty of source profiles in CMB apportionment.The data quality control measures can be used to construct of source profiles and the database,supporting for the veracity and effectiveness of source apportionment study.Results show that:For the coal-fired boiler,different characteristics were found at different source categories.SO42-,carbon fraction and crustal elements(Al,Si,Ca and Fe)were shown to be the major species of PM2.5 in given sources.Zn abundances of grate firing boilers were 3.2?54.1 times higher than those in other boilers.Pb abundance of emissions from coal burning were over 0.5%.Elemental ratios of V/Ni could be used as possible tracers of coal burning.For the fugitive dust,different chemical species could be used as tracers for various types of geological dust in the region that resulted from different anthropogenic influence.For example,elemental carbon,V and Zn can be used as tracers for urban paved road dust;Al,Si,K+ and NH4+ for agricultural soil;Al and Si for natural soil;and SO42-for urban resuspended dust.The enrichment factor analysis showed that Cu,Se,Sr and Ba are highly enriched by human activities in geological dust samples from south-west China.Elemental ratios are taken to highlight the features of geological dust from south-west China by comparing with northern urban fugitive dust,loess and desert samples.Low Si/Al and Fe/Al ratios can be used as markers to trace geological sources from southwestern China.High Pb/Al and Zn/Al ratios observed in urban areas demonstrated that urban geological dust is influenced seriously by non-crustal sources.The effect of uncertainties of source profiles are analyzed.The uncertainties of trace elements show the influences on CMB performance and mainly reflected in the contributions of corresponding source categories.Sensitivity of CMB model results to sub-source profiles are examined.The results show that the use of sub-source profiles do not impact the model apportainment results for biomass burning and geological dust,but coal combustion source conctributions are significantly influenced. |
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