Characterization of airborne carbonate over a site near Asian dust source regions during spring 2002 and its climatic and environmental significance

Abstract

[1] During spring 2002, three dust storm events were monitored by filter sampling in Xi'an near an Asian dust source region of northwest China. The carbonate (CO 3 2À ) fraction was determined by sample acidification and thermal evolution. The CO 3 2À accounted for 8.0 ± 0.8% of particles with aerodynamic diameter 2.5 mm (PM 2.5 ) during dust storms and 4.7 ± 3.0% of PM 2.5 between storms. The ratios of calcium to carbonate carbon were consistent with those of calcite (CaCO 3 ). The d C and d18 O abundances in dust storm samples were À2.7 ± 0.7% and À5.8 ± 1.5%, which differed from À8.3 ± 1.9% for d 13 C and À10.8 ± 2.0% for d 18O during normal conditions. The d 13C is positively correlated with d 18O values (r = 0.78). This first measurement of isotopic abundance in Asian dust indicates the potential to quantify its contribution at distant locations using receptor models. By increasing the alkalinity of ocean water in the Pacific Ocean and buffering the atmospheric acidity of east Asia, the large amounts of airborne CO 3 2À (as high as 44.8 Tg yr À1) entrained by Asian dust may provide an important atmospheric alkaline carbon reservoir for large-scale climatic and environmental changes.

Chemical Characteristics of Fine Particles (PM1) from Xi'an, China

“…Spring samples were more scattered, indicating greater variability in acid-base balance. We noted that six springtime PM 1 samples that plotted below the equiline were rich in Ca 2+ , consistent with previous studies that have shown that high mineral dust loadings in spring can buffer aerosol acidity Cao et al 2005b). The remaining twenty-five spring samples plotted above the 1:1 line, showing they were acidic.…”

“…This ion has been used as an indicator of Asian dust, which typically exhibits its highest concentrations in spring (Choi et al 2001;Cao et al 2005b;Shen et al 2007). Prior studies revealed that fugitive dust in the downtown (i.e., dust from road traffic, construction activities, and traditional street sweeping) and soil dust from outside of downtown caused high dust loading in spring in Xi'an, and these lead to high Ca 2+ concentrations Shen et al 2008).…”

“…The two dust events occurred from March 16 to 19 and from April 5 to 7, when the mean PM 1 mass values reached 208.7 µg m −3 and 152.5 µg m −3 , respectively. Numerous studies have shown that dust storms can lead to heavy PM loadings in urban and rural regions of China (Cao et al 2005b;Zhang et al 2005;Wang et al 2006;Shen et al 2009). However, the PM 1 mass concentrations during the two pollution episodes, which occurred on March 27 and from April 1 to 3, were higher than those in dust storms (PM 1 = 236.4 and 225.2 µg m −3 , respectively.…”

Characterization of Atmospheric Organic and Elemental Carbon of PM2.5 in a Typical Semi-Arid Area of Northeastern China

“…Long-range transport of Asian dust is one of the important sources of atmospheric aerosols in the downwind regions, particularly during the dust seasons. Asian dusts can influence ecosystems, environments, and climates (Sokolik and Toon, 1996;Sokolik et al, 2001;Han et al, 2004;Cao et al, 2005;Huang et al, 2006bHuang et al, , 2008. Some Asian dust may settle on the ocean's surface and provide nutrients (e.g., Fe 2+ ) to the oceanic biosphere (Zhuang et al, 1992).…”

PM2.5 Chemical Source Profiles of Emissions Resulting from Industrial and Domestic Burning Activities in India

“…Conversion of ion mass concentrations into micro equivalents was performed to calculate the cation/anion balance of PM 2.5 (Cao et al, 2005;Zhang et al, 2011;Tao et al, 2013). The cation and anion micro equivalents of particles were calculated as follows: The well balanced anion/cation (A/C) ratio must be 1.…”