The speciation of the elements on the surface of the particles collected during dust storm and non-dust storm in Beijing and Inner Mongolia was studied by XPS. The ma- jor species of iron on the surface were oxides, sulfate, silicate, FeOOH and minor part sorbed on SiO2/Al2O3. Sulfate is the dominant species of sulfur on the surface. SiO2 and Al2O3 are the main components of Si and Al on the surface respectively. One of the most important findings was that the Fe(II) (FeS and FeSO4) produced could account for up to 44.3% and 45.6% of the total Fe on the surface in the aerosol sample collected at that night and next day of the “peak” time of the dust storm occurring on March 20, 2002, while Fe2(SO4)3, one of the Fe(III) species on the surface decreased from 67.1% to 49.5% and 48.0% respectively. Both S and Fe en- riched on the surface of aerosol particles. Fe(II) accounted for 1.3%?5.3% of total Fe in bulk aerosol samples during dust storm. These results provided strong evidence to sup- port the hypothesis of the coupling between iron and sulfur in aerosols during the long-range transport, which would have important impact on the global biogeochemical cycle.
ZHANG Xingying1,2, ZHUANG Guoshun1,2,3, CHEN Jianmin2 & XUE Huaxin2 1. Center for Atmospheric Environment Study, Department of Chemistry, Beijing Normal University, Beijing 100875, China
In spite of increasing attention on Chinese aerosol, there has never been a country-wide survey of its general characteristics. This paper presents elemental data for aerosol at 23 sites in and around China, mostly drawn from the literature, and shows some of the large-scale patterns. Al, Na, and Se are used to represent the crustal, marine, and pollution components, respectively. Most of the patterns are aligned in SW–NE. Al and Na are highest to the NW and the SE, respectively, and their ratio changes rapidly near the coast. Se has a broad maximum over Central China, and the Se/Al ratio (an indicator of pollution vs. crustal aerosol) increases progressively from the NW to the SE. A simple index for simulating pollution aerosol, which uses population density, annual precipitation, and mean wind speed, adequately reproduces the large-scale pattern of pollution aerosol and shows how crustal Al in the NW gradually gives way to flyash Al toward the SE.
Jinghua GuoKenneth A. RahnGuoshun ZhuangShuifeng Wang
Objective To investigate the seasonal characteristics and the sources of elements and ions with different sizes in the aerosols in Beijing. Methods Samples of participate matters (PM2.5), PM10, and total suspended particle (TSP) aerosols were collected simultaneously in Beijing from July 2001 to April 2003. The aerosol was chemically characterized by measuring 23 elements and 18 water-soluble ions by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and ion chromatography (IC), respectively. Results The samples were divided into four categories: spring non-dust, spring dust, summer dust, and winter dust. TSP, PM10, and PM2.5 were most abundant in the spring dust, and the least in summer dust. The average mass ratios of PM>10, PM2.5-10, and PM2.5 to TSP confirmed that in the spring dust both the large coarse (PM>10) and fine particles (PM2.5) contributed significantly in summer PM2.5, PM2.5-10, and PM>10 contributed similar fractions to TSP, and in winter much PM2.5. The seasonal variation characteristics of the elements and ions were used to divide them into four groups: crustal, pollutant, mixed, and secondary. The highest levels of crustal elements, such as Al, Fe, and Ca, were found in the dust season, the highest levels of pollutant elements and ions, such as As, F-, and Cl-, were observed in winter, and the highest levels of secondary ions (SO42-, NO3-, and NH4+) were seen both in summer and in winter. The mixed group (Eu, Ni, and Cu) showed the characteristics of both crustal and pollutant elements. The mineral aerosol from outside Beijing contributed more than that from the local part in all the reasons but summer, estimated using a newly developed element tracer technique.
