Submicron aerosol analysis and organic source apportionment in an urban atmosphere in Pearl River Delta of China using high-resolution aerosol mass spectrometry

Abstract

[1] The Pearl River Delta (PRD) region in South China is one of the most economically developed regions in China while also noted for its severe air pollution, especially in the urban environments. In order to understand in depth the aerosol chemistry and the emission sources in PRD, an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed at an urban site in the Hong Kong-Shenzhen metropolitan area between 25 October and 2 December 2009. Ten minute-resolved measurement data were analyzed, and an average mass concentration of 44.5 ± 34.0 mg m −3 was calculated for the entire campaign. On average, organic matter was the most abundant PM 1 component accounting for 39.7% of the total mass, followed by sulfate (24.5%), black carbon (measured by aethalometer, 14.0%), ammonium (10.2%), nitrate (10.0%), and chloride (1.6%). Moreover, organic matter comprised an increasing fraction of the PM 1 loading as the PM 1 loading increased, denoting its key role in particulate pollution in this region. Calculations of organic elemental composition based on the high-resolution organic mass spectra obtained indicated that C, H, O, and N on average contributed 33.8%, 55.1%, 10.2%, and 0.9%, respectively, to the total atomic numbers of organic aerosol (OA), which corresponded to an OM/OC ratio (the ratio of organic matter mass/organic carbon mass) of 1.57 ± 0.08. Positive matrix factorization analysis was then conducted on the high-resolution organic mass spectral data set. Four OA components were identified, including a hydrocarbon-like (HOA), a biomass burning (BBOA), and two oxygenated (LV-OOA and SV-OOA) components, which on average accounted for 29.5%, 24.1%, 18.8%, and 27.6%, respectively, of the total organic mass. The HOA was found to have contributions from both fossil fuel combustion and cooking emissions, while the BBOA was well correlated with acetonitrile, a known biomass burning marker. The LV-OOA and SV-OOA corresponded to more aged and fresher secondary organic aerosol, respectively. The diurnal variations of the LV-OOA and SV-OOA showed significant increase in concentration in the daytime, denoting their substantial photochemical formation. Back trajectory analysis indicated that the short-range regional transport from the northeast was the key factor leading to severe submicron aerosol pollution in this area. The HR-ToF-AMS measurement results in this campaign are completely compared with a previous paper that reports the HR-ToF-AMS measurement results at a rural site in PRD in the same season, based on which the regional pollution characteristics of submicron particle in PRD were analyzed. (2011), Submicron aerosol analysis and organic source apportionment in an urban atmosphere in Pearl River Delta of China using high-resolution aerosol mass spectrometry,

Physical and chemical characterization of ambient aerosol by HR‐ToF‐AMS at a suburban site in Hong Kong during springtime 2011

“…During the campaign, total nonrefractory PM 1 (NR-PM 1 ) as measured by the AMS ranged from 0.8 to 72.4 μg/m 3 with an average of 14.5 ± 9.7 μg/m 3 , which is within the upper range of measured concentrations in various other urban environments in the U.S. and Europe [Zhang et al, 2007b] but is significantly lower than what has been observed with AMS in other Chinese cities, e.g., Beijing, Shenzhen, and Kaiping [He et al, 2011;Huang et al, 2010Huang et al, , 2011b. On average, sulfate and organics combined amounted to 79.2% of nonrefractory fine particle mass (Figure 2a) with average concentrations of 7.9 ± 4.8 and 4.4 ± 3.6 μg/m 3 respectively.…”

Long-term impacts of aerosols on precipitation and lightning over the Pearl River Delta megacity area in China

“…The exponential decreasing profile of aerosol vertical distribution is supported by aircraft measurement during PRIDE-PRD 2004 . The most recent analysis from high-resolution aerosol mass spectrometer (AMS) measurements (He et al, 2011) provides a similar mass concentration of ammonium sulfate to the value employed in this study. The mass and number concentration of ammonium sulfate over the sea are assumed to be half of the values over the continent.…”

CCN closure study: Effects of aerosol chemical composition and mixing state

“…The OPOA time series is similar to that of nitrate, m/z 55 and m/z 60, suggesting that the aerosols were not aged but originated from different POA sources ( Figure S4). Earlier studies have also suggested that residual BBOA can accompany HOA in PMF analysis [He et al, 2011]. We speculate that OPOA is a mixture of both biomass burning and cooking aerosols.…”

“…BBOA-1 and BBOA-2 are correlated with m/z 60 (R 2 = 0.92 and 0.33, respectively) and m/z 73 (R 2 = 0.89 and 0.38, respectively). The contributions of residual BBOA, cooking, trash burning, and slightly oxidized SOA have been shown to be difficult to separate; thus, it is not surprising that a contribution from m/z 60, which increases the O:C ratio, is present in HOA [He et al, 2011;Aiken et al, 2009]. Elemental O:C ratios for different profile factors were obtained after fitting peaks in HR data analysis.…”