Land use patterns and SO2 and NO2 pollution in Ulaanbaatar, Mongolia

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Urban Pollution Studies

Background:

• Ulaanbaatar faces significant air quality challenges, particularly concerning sulfur dioxide (SO2) and nitrogen dioxide (NO2) pollution.
• Understanding the spatial distribution and sources of these pollutants is crucial for developing effective mitigation strategies in urban environments.

Purpose of the Study:

• To investigate the spatial distribution and source contributions of ambient sulfur dioxide (SO2) and nitrogen dioxide (NO2) in Ulaanbaatar, Mongolia.
• To assess the influence of seasonal variations and proximity to emission sources (ger areas, major roads, power plants, city center) on pollutant concentrations.

Main Methods:

• Collected 2-week ambient SO2 and NO2 concentration samples at 38 sites across three seasons (warm, cold, moderate).
• Utilized Ogawa passive samplers for SO2 and NO2 collection, with analysis via ion chromatography and spectrophotometry.
• Employed stepwise and multiple regression models to determine the contribution of emission proxies (distance to roads, ger areas, power plants, city center) to ambient concentrations.

Main Results:

• Significantly higher SO2 and NO2 concentrations were observed during the cold season compared to warm and moderate seasons at all sites.
• SO2 concentrations were notably higher in ger areas, while NO2 concentrations were elevated near major roads and traffic zones.
• Regression models indicated that SO2 and NO2 concentrations decreased with increasing distance from ger areas, major roads, and the city center, with varying percentages across seasons.

Conclusions:

• SO2 and NO2 pollution levels in Ulaanbaatar are critically high, particularly during winter, driven by seasonal factors and urban land use patterns.
• Proximity to ger areas, major roads, power plants, and the city center are significant determinants of ambient SO2 and NO2 concentrations.
• The findings highlight the need for targeted interventions addressing emissions from residential heating in ger areas and traffic-related pollution.