Chemical Characteristics of Trace Elements and Water-Soluble Ions in Marine Aerosols over Pengchiayu Island

Three hundred and sixty five aerosol samples were collected at Pengchiayu Island from December 2004 to February 2006. All of the samples were analyzed for water-soluble ions Na+, Mg+2, K+, Ca2+, NH4+, Cl-, NO3- and SO42- , using ion chromatography. Samples collected from March to May of 2005 were also analyzed for trace elements Al, Fe, Na, Mg, K, Ca, Sr, Ba, Ti, Mn, Co, Ni, Cu, Zn, Cd, Pb and Cr, using inductively coupled plasma mass spectrometry.he concentrations of water-soluble ions in aerosols collected at Pengchiayu island displayed strong seasonal variations with higher concentrations in winter and spring, and lower concentrations in summer. The aerosols at Pengchiayu Island contain high proportions of crustal and anthropogenic materials as compared with other areas, which are mainly exported from mainland China. The Cl-/Na+ ratios in aerosols are lower than that of sea water suggesting that there are chloride depletions in Pengchiayu aerosols. The calculations of molar ratios of NH4+/nss-SO42- reveal that the compound of sulfate in aerosols is mainly in the form of NH4HSO4. Wind populations analysis shows that the concentrations of water-soluble ions in north wind population are 1.1 to 1.6 times higher than that of south wind population. It can be found that the atmospheric concentrations of NO3- and nss-SO42- at pengchiayu Island in 2005 are higher nearly double than that of in 1996. hree dust storm episodes have been identified in this study during the springtime of 2005. Among them the most heavily dust storm occurred in April 10 to 15, and the very high concentrations for most of elements are observed in this dust storm samples, especially for crustal elements. Airmass backward trajectories analysis suggests that the source materials of dust storm are from Mongolia in north China, which is transported to Pengchiayu Island through long-range transport. During the dust storm periods the concentration ratios of Fe/Al in aerosols generally fall down to about 0.5, in the meantime, the concentrations of crustal derived Na will be increased significantly, and he proportions of seawater derived Na will be reduced relatively. Principal component analysis (PCA) shows that during the dust storm season the variability of chemical composition of aerosols at Pengchiayu Island is greatly influenced by the supply of land source materials including crustal and anthropogenic materials, and the impact of seawater derived materials is relatively small. Based on PCA study, the anthropogenic sources can be further classified into two groups: high temperature burning type components Ni, Cu and Cr, and low temperature burning type components K+, NH4+, nss-SO42-, NO3-, Cd and Pb.