Chemical Characteristics of Airborne Particulate Matter during the Winter Season in Ulaanbaatar

抄録

Atmospheric pollution by airborne particulate matter (PM) in Ulaanbaatar, particularly in the winter season, is very serious problem in Mongolia. The chemical compositions of PM samples were measured in Ulaanbaatar in the winters of 2012 and 2013. The concentration trends for both PM_2.5 and PM₁₀ in the city center were similar and the PM_2.5/PM₁₀ ratios were about 0.8. Arsenic, Pb and Zn were weighted toward the fine size range, whereas Ca, Fe and Mn dominated the coarse size range. The PM ratios for acidic ions, the ions assumed to be derived from coal combustion, were about 0.8, except for fluoride.The average winter concentrations for PM₁₀ samples collected simultaneously at three separate locations in the city were 167 μg/m³ for the city center, 422 μg/m³ for an area dominated by Gers housing(traditional Mongolian yurt dwellings houses) and 155 μg/m³ for an area with traffic congestion. Total carbon represented the largest component of PM, accounting for approximately half of the total. The organic carbon (OC) concentration of PM₁₀ samples in the Gers area was significantly higher than that of other areas. Within the five fractions of OC, the OC1 fraction with gasification at low temperature(120°C) in the Gers area was consistently higher than in other areas.