Background: Dust storm originated from the northwest region of China brought dust particles for Shanghai every spring

which resulted in serious particulate pollution. However

the studies of the impact of dust storm on the Shanghai atmospheric aerosols were limited to the concentrations of ions and elements. It is considered that the chemical species of atmospheric aerosols were much more necessary for the evaluation of the impact of dust storm on the particulate pollution in Shanghai. Purpose: Based on the elements concentration variations

backward trajectories of air masses and chlorine

calcium

sulfur species in aerosols during the dust event

the impact of dust storm on the chemical species of aerosols in Shanghai was studied. Methods: Elements concentrations of the samples were analyzed by X-ray fluorescence(XRF) based on synchrotron radiation. To identify the potential importance of different source regions on aerosol composition during dust events

the air mass trajectories were calculated by using the model HYSPLIT version 4 developed by NOAA/ARL. Chemical species of S

Cl

Ca were analyzed by synchrotron radiation X-ray absorption near edge structure(XANES). Sulfur K-edge XANES is capable of distinguishing various sulfate species in a non-destructive way and we used linear combination fitting procedure to quantify the concentrations of sulfate species in PM. Results: Elements concentration variations during the dust storm period showed that crust elements(Si

Al

Ca

K

Mg

Fe

Ti) in particles increased substantially during dust storm.However

pollution elements(S

Zn

Pb

Cu

V

Cr

As) from local region decreased by the clean effect of dust storm.Combined XANES of S

Cl

Ca in particulate samples with backward trajectories

the possible sources and reasons of their chemical species were studied. During dust storm

sulfur mainly existed as CaSO4·2H2O

Cl existed as organic chloride and Cl

Ca existed as CaCO3. In the samples of other days

sulfur was mainly existed as(NH4)2SO4

Cl existed as organic chloride and Ca existed as Gypsum. The source of Cl was sea salts which brought by dust storm along the way. Gypsum(CaSO4·2H2O) was formed in the reactions of CaCO3and SO42 during the transportation.Conclusion: It is shown that synchrotron radiation XANES is a powerful tool to identify chlorine

calcium and especially sulfur species in aerosol samples. Dust storm not only transported amount of crust particles but also brought particles along the way to atmosphere environment in Shanghai. During the transportation

dust particles could chemically react with the pollution particles of the local region.