| Zhengzhou is a developing region that is heavily polluted with high levels of particle air pollution, which take a negative effect on environment and climate. Particulate matter can carry plenty harmful substances with it such as heavy metals, which are known or suspected to cause adverse health effect on humans. It is therefore, highly desirable to understand the particle matter pollution especially PM2.5and the metals it carried with in Zhengzhou. In this study, fine particulate matter (PM2.5) was collected with a high volume sampler TE-6070D in an industrial district of Zhengzhou from Jan.2010to Jan.2011.19elements of the samples were determined by Agilent-7500cx ICP-MS to study the characteristics and sources of PM2.5in Zhengzhou. The results showed that:(1) The average concentrations of PM2.5is175.4μg/m3, which is significantly higher than the assessent threshold of EU (25μg/m-3;European Commission), WHO (10μg m-3), and USA (15μg m-3), The seasonal variability of PM2.5is apparent, the average concentrations of PM2.5arel79.6,131.6,185.5and210.1μg/m3for spring, summer, autumn and winter, respectively.(2) The concentrations of the19species measured follow the order of Fe> K> Ca> Al> Zn> Mg> Pb> Mn> Na> Ba> Cu> As> Cr> Sr> Se> Cd> V> Ni> Co. The concentrations of Co, Cd andMn measured in this study are high, whereas Pb is low in comparison with other cities in China; but most elements are much higher than the average levels in Mexico City, Los Angles and Toronto. Toxic mentals Cd and As concentration exceed EU Air quality Framework Directive. In the case of V, the proposed24-h concentration is1ng/m3. A value be exceeded at the rate of97%during the sampling campaign. Annual average concentrations of Pb were found below the limit values at all samples. The seasonal variability of metal concentration shows that high values of crust elements such as Fe, Ca, Al, Mg and Ba appear in spring when sandstorm weather usually occurs, which can bring soil dust rich in Ca, Fe and Al; high levels of K, Na, Mn, Co, Zn, V, Cr, As, Se, Sr, Cd and Pb appeared in winter, while low levels of most elements were measured in summer.(3) Correlation Analysis shows that Al, Ca, Mg, Fe and Sr have Spearman R’s of0.82-0.93between each other, indicating the existence of a common emission source: soil dust; K was correlated with Se, Na and As, they may come from combustion sources; Pb, Cu, Cd and Se are correlated strongly with Zn as they aretypically anthropogenic emissions from some industrial and traffic process. Enrichment Factor (EF) Analysis shows that the EF values for heavy metals such as Cu, As, Zn, Pb and Cd were much higher than100, it clealy indicates that they are mainly originated from anthropogenic sources. Factor analysis on the chemical composition of PM2.5shows that soil dust, biomass and coal fuel combustion, metal-working industry, fuel and traffic are the main sources of the elements in the research region. Samples were also analyzed by PMF (Positive Matrix Factorization) to find the main sources of PM2.5, the statistics of soluble ions, elements and EC/OC were included in PMF analysis. The result shows that secondary aerosol, soil dust and coal combustion are the major sources of PM2.5which contribute26.7%,25.9%and19.1%of total PM2.5mass concentration. The contributions of other sources are biomass burning+Oil combustion16.3%, vehicle9.6%, industrial2.3%. |
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