[Show abstract][Hide abstract] ABSTRACT: A one-year-long aerosol characterization study was conducted from July 2002 through July 2003, in Beijing, China. Twenty-four hour PM2.5 and PM10 filter samples were collected, and about 50 aerosol samples of each type were obtained. Organic, elemental, and total carbon, levoglucosan and other organic compounds, and inorganic ionic species were measured. The overall mean PM mass concentrations were 99 and 175 μg/m3 for PM2.5 and PM10, respectively. Total carbon was the main component in both PM2.5 and PM10, with overall mean concentrations of 21 and 30 μg/m3, respectively. Of the organic compounds measured, levoglucosan exhibited the highest levels (overall mean of 0.31 ng/m3 in PM2.5 and of 0.40 ng/m3 in PM10). Sulfate was the most prominent inorganic ionic species, with overall mean levels of 15.6 and 17.0 μg/m3 in PM2.5 and PM10, respectively. Most components measured were predominantly present in the PM2.5 size fraction; the overall mean PM2.5/PM10 ratio was typically in the range of 0.7-0.8, but this ratio was only 0.55 for the PM mass and for Ca2+ it was as low as 0.19. In PM2.5, total carbon exhibited relatively larger concentration levels (30 μg/m3) in winter than in the other seasons. K+ also exhibited a relatively high concentration level in the winter season, with 2.3 μg/m3 in PM2.5. The contribution from biomass burning to K+ in PM2.5 was estimated on the basis of the levoglucosan data and the minimum K+/levoglucosan ratios obtained throughout the year; it was found that the contribution was largest in autumn, with 44%.
Full-text · Article · Jul 2014 · Atmospheric Pollution Research
[Show abstract][Hide abstract] ABSTRACT: Even after its being phased out in gasoline in the late 90s, lead (Pb) is still present at relatively high levels in the atmosphere of Beijing, China (0.10–0.18 μg m−3). Its origin is subject to debate as several distinct sources may contribute to the observed pollution levels. This study proposes to constrain the origin(s) of Pb and strontium (Sr) in aerosols, by coupling both Pb and Sr isotope systematics. The characterisation of the main pollution sources (road traffic, smelters, metal refining plants, coal combustion, cement factories, and soil erosion) shows that they can unambiguously be discriminated by the multi-isotope approach (206Pb/204Pb and 87Sr/86Sr). The study of total suspended particulates (TSP) and fine particles (PM2.5) from Beijing and its vicinity indicates that both size fractions are controlled by the same sources. Lead isotopes indicate that metal refining plants are the major source of atmospheric lead, followed by thermal power stations and other coal combustion processes. The role of this latter source is confirmed by the study of strontium isotopes. Occasionally, emissions from cement plants and/or input from soil alteration are isotopically detectable.
[Show abstract][Hide abstract] ABSTRACT: Twelve filter samples were sampled monthly during a continuous 1-year campaign at a remote site, Nam Co in central Tibetan Plateau. The total aerosol concentrations ranged from 0.48 μg/m 3 to 36.11 μg/m 3 with the annual average of 6.74 μg/m 3 , reflecting a typical background level. The composition and morphology of atmospheric aerosols with size ranging from 0.5 to 10 μm were investigated using a scanning electron microscope coupled with energy dispersive X-ray analysis. Then aerosol particles were classified into 7 groups: soot, tar ball, aluminosilicates/quartz, calcium sulfate, Ca/Mg carbonate, Fe/Ti oxide, and biological particle. Aerosol optical properties from the sun photometer and the results obtained by SEM-EDX could support and verify each other, providing complementary information on aerosol characteristics at Nam Co. Two distinct types of air masses arriving at Nam Co correspond to different aerosol constituent, showing that the summer monsoon circulation may bring considerable pollution from South Asia, while the westerly flow dominated in winter is relative clean.
Full-text · Article · Sep 2009 · Aerosol and Air Quality Research
[Show abstract][Hide abstract] ABSTRACT: Atmospheric aerosols were collected during the scientific expedition to Mt. Qomolangma (Everest) in May-June, 2005. The elemental concentrations of the aerosols were determined by inductively coupled plasma mass spectrometry. This yielded data for the concentration of 14 elements: Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, and Pb. The mean elemental concentrations were generally comparable with those from central Asia and the Arctic, while much higher than those from Antarctic. Size, morphology, and chemical composition of 900 individual aerosol particles were determined by scanning electron microscopy and energy-dispersive X-ray microanalysis. Based on morphology and elemental composition, the particles were clustered into eight groups: soot (8%), tar ball (3%), alumosilicates/silica (55%), calcium sulfate (16%), Ca/Mg carbonate (2%), Fe/Ti-rich particles (3%), Pb-rich particles (1%), and biological particles (12%). The sampling site, located at 6,520 m in the Himalayas, is particularly remote and located at high altitude. Nonetheless, high aerosol enrichment factors for copper, chromium, lead, nickel, vanadium, and zinc all suggest the influence of long-range transported pollution, while enrichment in calcium and the presence of alumino-silicates in individual particle analyses indicates a distinct mineral dust influence. The backward air mass trajectories showed that the northwestern part of India may contribute to the atmospheric aerosol in the central high Himalayas.
Full-text · Article · Jan 2009 · Environmental Monitoring and Assessment
[Show abstract][Hide abstract] ABSTRACT: The total nitrogen (TN) and water-soluble nitrogenous ions were determined by using CHN Elemental Analyzer and ion chromatography method, respectively, from November 24, 1998 to February 12, 1999 in Beijing. The average concentrations of TN, NH(4) (+) and NO(3) (-) were 10.62 microg N m(-3), 6.67 microg m(-3) and 10.01 microg m(-3), respectively. The total inorganic nitrogen (IN) calculated from NH(4) (+) and NO(3) (-) was 7.45 microg N m(-3), accounting for 70% of TN, i.e., 30% of TN existed as organic nitrogen form (ON). The correlation between ON and other pollution tracers showed that, coal combustion, biomass burning, soil humic matter and secondary formation were the important sources of ON in particulate matter in Beijing.
No preview · Article · Oct 2008 · Bulletin of Environmental Contamination and Toxicology
[Show abstract][Hide abstract] ABSTRACT: Two series of size-selective aerosol samples, PM2.5 and PM10, were collected in Beijing from July 2002 to July 2003. The samples were analyzed for levoglucosan and related saccharidic compounds, organic and elemental carbon, and ionic species. Levoglucosan and related saccharidic compounds were mostly present in the fine size fraction. The contribution from biomass burning to the carbonaceous aerosol in Beijing was estimated; biomass burning was responsible for 18–38% of the PM2.5 organic carbon and for 14–32% of the PM10 organic carbon. The biomass burning marker levoglucosan was present all year round in Beijing. High levoglucosan concentrations in October and November were attributed to corn field burning and burning of fallen leaves, while the high level observed on 7 May 2003 was tracked back to a boreal forest fire more than 1000 km away in northeastern China. The biomass burning contribution to the Beijing aerosol is made up of two parts, a background component, which is due to biofuel burning all year round in the neighboring countryside households, and a superimposed component from seasonal crop burning events and wild fires.
[Show abstract][Hide abstract] ABSTRACT: Scanning electron microscopy–energy dispersive X-ray analysis (SEM–EDX) was used for the analysis of 2500 single particles in five atmospheric aerosol samples collected during the spring and summer of 2000 in Beijing, China. Mineral dust appeared to be the dominant particles during an Asian dust episode, while in other circumstances mineral dust and S-containing particles constituted the major particle components. During anthropogenic pollution episodes in the summer, a large abundance of S-containing particles featured the atmospheric aerosol. Chemical and size distribution characteristics are discussed for Ca–S, K–S and Ca–K–S particle classes. Formation of Ca–K–S and other S-containing particle classes with high abundance was closely related to meteorological conditions such as relative humidity and cloud coverage. Simple and composite sulfate particles with an elongated crystalline morphology were detected which appear to be indicative of aqueous phase oxidation, such as in-cloud processing for sulfate formation pathway.
No preview · Article · Nov 2005 · Atmospheric Environment
[Show abstract][Hide abstract] ABSTRACT: Using Monte Carlo simulation, the geometric and matrix effects on intensity and intensity ratio measured by EPMA were investigated for both synthetic particles and biomass burning particles. Three particulate standards, KCl, K2SO4, KHSO4, were prepared and measured along with biomass burning particles. The modified CASINO program (University of Sherbrooke, Quebec, Canada) at the University of Antwerp, Belgium was used. The relative intensities obtained by the UA version of the CASINO program appear to be in line with those from experiments.The CASINO program and iterative procedures were applied to quantitatively determinate the atomic fraction of K, Cl and S in particulate standard and real samples. After correcting the geometric and matrix effects, the atomic fraction ratio of K to Cl in KCl sample was found to be 1.007±0.025, 0.996±0.013 and 1.011±0.019 for experiments with high voltages of 15, 20 and 25 keV, respectively. The same procedure was also applied to K2SO4 and KHSO4 standard particle sample. The atomic fraction ratio of K to S was 1.945±0.049 (25 keV) for K2SO4 and 1.014±0.072 (20 keV) for KHSO4. These ratios obtained are close to the theoretic values 1 or 2. Reasonable data were obtained for biomass burning particles, indicating that it is possible to perform chemical speciation.
No preview · Article · May 2002 · Analytica Chimica Acta