Tsatsral Batmunkh

Chemical characteristics of fine particulate matters measured during severe winter haze events in Ulaanbaatar, Mongolia

In order to investigate the chemical characteristics of atmospheric aerosol measured during a severe winter haze event, 12-hr PM2.5 (particulate matter with an aerodynamic diameter ≤2.5 μm) samples were collected at an urban site in Ulaanbaatar, Mongolia, from January 9 to February 17, 2008. On average, 12-hr PM2.5 mass concentration was 105.1 ± 34.9 μg/m3. Low PM2.5 mass concentrations were measured when low pressure developed over central Mongolia. The 12-hr average organic mass by carbon (OMC) varied from 6.4 to 132.3 μg/m3, with a mean of 54.9 ± 25.4 μg/m3, whereas elemental carbon (EC) concentration ranged from 0.1 to 3.6 μgC/m3, with a mean of 1.5 ± 0.8 μgC/m3. Ammonium sulfate was found to be the most abundant water-soluble ionic component in Ulaanbaatar during the sampling period, with an average concentration of 11.3 ± 5.0 μg/m3. In order to characterize the effect of air mass pathway on fine particulate matter characteristics, 5-day back-trajectory analysis was conducted, using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The haze level was classified into three categories, based on the 5-day air mass back trajectories, as Stagnant (ST), Continental (CT), and Low Pressure (LP) cases. PM2.5 mass concentration during the Stagnant condition was approximately 2.5 times higher than that during the Low Pressure condition, mainly due to increased pollutant concentration of OMC and secondary ammonium sulfate. Implications: Mongolia is experiencing rapid rates of urbanization similar to other Asian countries, resulting in air pollution problems by the growing number of automobiles and industrialization. Ulaanbaatar, capital of Mongolia, is inherently vulnerable to air pollution because of its emission sources, topography, and meteorological characteristics. Very limited measurements on chemical characteristics of particulate matter have been carried out in Ulaanbaatar, Mongolia.

Time-resolved measurements of PM2.5 carbonaceous aerosols at Gosan, Korea.

ABSTRACT In order to better understand the characteristics of atmospheric carbonaceous aerosol at a background site in Northeast Asia, semicontinuous organic carbon (OC) and elemental carbon (EC), and time-resolved water-soluble organic carbon (WSOC) were measured by a Sunset OC/EC and a PILS-TOC (particle-into-liquid sampler coupled with an online total organic carbon) analyzer, respectively, at the Gosan supersite on Jeju Island, Korea, in the summer (May 28–June 17) and fall (August 24–September 30) of 2009. Hourly average OC concentration varied in the range of approximately 0.87–28.38 μgC m−3, with a mean of 4.07 ± 2.60 μgC m−3, while the hourly average EC concentration ranged approximately from 0.04 to 8.19 μgC m−3, with a mean of 1.35 ± 0.71 μgC m−3, from May 28 to June 17, 2009. During the fall season, OC varied in the approximate range 0.9–9.6 μgC m−3, with a mean of 2.30 ± 0.80 μgC m−3, whereas EC ranged approximately from 0.01 to 5.40 μgC m−3, with a mean of 0.66 ± 0.38 μgC m−3. Average contributions of EC to TC and WSOC to OC were 26.0% ± 9.7% and 20.6% ± 7.4%, and 37.6% ± 23.5% and 57.2% ± 22.2% during summer and fall seasons, respectively. As expected, clear diurnal variation of WSOC/OC was found in summer, varying from 0.22 during the nighttime up to 0.72 during the daytime, mainly due to the photo-oxidation process. In order to investigate the effect of air mass pathway on the characteristics of carbonaceous aerosol, 5-day back-trajectory analysis was conducted using the HYSPLIT model. The air mass pathways were classified into four types: Continental (CC), Marine (M), East Sea (ES) and Korean Peninsula (KP). The highest OC/EC ratio of 3.63 was observed when air mass originated from the Continental area (CC). The lowest OC/EC ratio of 0.79 was measured when air mass originated from the Marine area (M). A high OC concentration was occasionally observed at Gosan due to local biomass burning activities. The contribution of secondary OC to total OC varied approximately between 8.4% and 32.2% and depended on air mass type. IMPLICATIONS Organic material contributes approximately 20–90% of the total fine particulate mass concentration at different sites over the world depending on location and season. Organic carbon consists of hundreds of compounds with a wide range of chemical and optical properties. A better understanding of the chemical characteristics of carbonaceous aerosol influenced by increasing anthropogenic pollution in the downwind regions of the East Asian continent is needed in order to determine their impacts on regional air quality and climate change.

Optical and hygroscopic properties of long-range transported haze plumes observed at Deokjeok Island off the west coast of the Korean Peninsula under the Asian continental outflows

An intensive field campaign was conducted on Deokjeok Island off the west coast of the Korean Peninsula during spring 2009 to characterize the optical and hygroscopic properties of Asian continental outflows. A slightly high wavelength dependence of light absorption coefficient, α of 1.6 ± 0.05 (average ± 1· standard deviation), and a low humidity-dependent light scattering enhancement factor at 80% relative humidity, f(80%) (2.0 ± 0.2), were obtained when air masses originated from the northern part of China (N China), compared to those obtained when air masses originated from the eastern part of China (E China) (α = 1.4 ± 0.1; f(80%) = 2.4 ± 0.2). The relatively high α and low f(80%) during the N China compared to those during the E China were consistent with a relatively high mass ratio of organic aerosol to sum of SO42−, NO3−, and NH4+ during the N China (1.01 ± 0.17) compared to the E China episode (0.25 ± 0.13). This result indicates the importance of organic aerosol on aerosol optical and hygroscopic properties of haze plumes. Single scattering albedo (SSA) of dry particulate matter with a diameter less than or equal to 2.5 µm (PM2.5) (0.92 ± 0.01) and mass scattering efficiency (MSE) of dry PM2.5 at 550 nm wavelength during the E China episode (3.6 ± 0.3 m2 g−1) were higher than those previously obtained at the air mass source regions in China (SSA = ~0.8; MSE = ~3.0 m2 g−1), implying that optical properties of PM2.5 were significantly altered during long-range atmospheric transport.

Comparison of the physical and chemical characteristics of fine road dust at different urban sites

ABSTRACT The size distribution and chemical components of a fine fraction (<2.5 μm) of road dust collected at urban sites in Korea (Gwangju) and Mongolia (Ulaanbaatar) where distinct urban characteristics exist were measured. A clear bimodal size distribution was observed for the resuspended fine road dust at the urban sites in Korea. The first mode peaked at 100–110 nm, and the second peak was observed at 435–570 nm. Ultrafine mode (~30 nm) was found for the fine road dust at the Mongolia site, which was significantly affected by residential coal/biomass burning. The contribution of the water-soluble ions to the fine road dust was higher at the sites in Mongolia (15.8–16.8%) than at those in Korea (1.2–4.8%). Sulfate and chloride were the most dominant ionic species for the fine road dust in Mongolia. As (arsenic) was also much higher for the Mongolian road dust than the others. The sulfate, chloride, and As mainly come from coal burning activity, suggesting that coal and biomass combustion in Mongolia during the heating season should affect the size and chemical components of the fine road dust. Cu (copper) and Zn (zinc), carbonaceous particles (organic carbon [OC] and elemental carbon [EC]) increased at sites in Korea, suggesting that the fine road dust at these sites was significantly affected by the high volume of traffic (engine emission and brake/tire wear). Our results suggest that chemical profiles for road dust specific to certain sites should be applied to more accurately apportion road dust source contributing to the ambient particulate matter. Implications: Size and chemical characteristics of fine road dust at sites having distinct urban characteristics were examined. Residential coal and biomass burning and traffic affected physiochemical properties of the fine road dust. Different road dust profiles at different sites should be needed to determine the ambient PM2.5 sources more accurately.

Optical and thermal characteristics of carbonaceous aerosols measured at an urban site in Gwangju, Korea, in the winter of 2011.

ABSTRACT Carbonaceous components (organic carbon [OC] and elemental carbon [EC]) and optical properties (light absorption and scattering) of fine particulate matter (aerodynamic diameter <2.5 μm; PM2.5) were simultaneously measured at an urban site in Gwangju, Korea, during the winter of 2011. OC was further classified into OC1, OC2, OC3, and OC4, based on a temperature protocol using a Sunset OC/EC analyzer. The average OC and EC concentrations were 5.0 ± 2.5 and 1.7 ± 0.9 μg C m−3, respectively. The average single-scattering albedo (SSA) at a wavelength of 550 nm was 0.58 ± 0.11, suggesting that the aerosols observed in the winter of 2011 had a local warming effect in this area. During the whole sampling period, “stagnant PM” and “long-range transport PM” events were identified. The light absorption coefficient (babs) was higher during the stagnant PM event than during the long-range transport PM event due to the existence of abundant light-absorbing OC during the stagnant PM event. In particular, the OC2 and OC3 concentrations were higher during the stagnant PM event than those during the long-range transport event, suggesting that OC2 and OC3 might be more related to the light-absorbing OC. The light scattering coefficient (bscat) was similar between the events. On average, the mass absorption efficiency attributed to EC (σEC) was 9.6 m2 g−1, whereas the efficiency attributed to OC (σOC) was 1.8 m2 g−1 at λ = 550 nm. Furthermore, the σEC is comparable among the PM event days, but the σOC for the stagnant PM event was significantly higher than that for the long-range transport PM event (1.7 vs. 0.5). Implications: Optical and thermal properties of carbonaceous aerosol were measured at Gwangju, and carbonaceous aerosol concentration and optical property varied between “stagnant PM” and “long-range transport PM” events. More abundant light absorbing OC was observed during the stagnant PM event.