Element composition and source apportionment of atmospheric aerosols over the China Sea

Four categories of different size marine aerosols (PM1.0, PM1.0-2.5, PM2.5-10 and PM10-100) were collected from the Yellow Sea and East China Sea in the spring of 2011 and analyzed for 22 elements by inductively coupled plasma-mass spectrometry (ICP-MS). The enrichment factors and air mass backward trajectory analysis were used to identify the potential sources. During the sampling periods, two sampling areas were influenced by Asian Dust on the basis of Al concentrations (an indicator of mineral dust). Average mass concentrations of particles showed relatively higher values in the Yellow Sea except PM2.5-10. Al, Ba, Ca, Fe, Mg, Ti, Na, K, Pb, Zn, Cr, P and Zr were abundant elements and they accounted for more than 96% of the total concentrations of elements in all samples of the two areas. High levels of trace elements were associated with the airflow from Asia as the air passed over heavily populated and industrialized regions before reaching the northwest Pacific Ocean. For the crustal elements, there were higher levels in the East China Sea, while the anthropogenic elements showed higher levels in the Yellow Sea. These results indicated that Asian Dust Storm had more effects on East China Sea during the sampling periods, and Yellow Sea suffered from more influence by human activities. Size distribution analysis revealed that elements derived from crust and anthropogenic sources tend to reside in fine particles and owing to the long distance away from the land, the concentrations of anthropogenic elements in PM2.5 were slightly higher in the East China Sea than those in the Yellow Sea. The results also suggested that the impact of Asian Dust presented a downward trend from west to east and from north to south in general.