Articles | Volume 15, issue 4
Atmos. Chem. Phys., 15, 1683–1705, 2015
Atmos. Chem. Phys., 15, 1683–1705, 2015
Research article
18 Feb 2015
Research article | 18 Feb 2015

Source sector and region contributions to BC and PM2.5 in Central Asia

S. Kulkarni1,*, N. Sobhani1,2, J. P. Miller-Schulze3,4, M. M. Shafer3,4, J. J. Schauer3,4, P. A. Solomon5, P. E. Saide1, S. N. Spak1,6, Y. F. Cheng1,**, H. A. C. Denier van der Gon7, Z. Lu6, D. G. Streets8, G. Janssens-Maenhout9, C. Wiedinmyer10, J. Lantz11, M. Artamonova12, B. Chen13, S. Imashev13, L. Sverdlik13, J. T. Deminter3, B. Adhikary1,***, A. D'Allura14, C. Wei1,****, and G. R. Carmichael1,2 S. Kulkarni et al.
  • 1Center for Global and Regional Environmental Research, University of Iowa, Iowa City, IA, USA
  • 2Department of Chemical & Biochemical Engineering, University of Iowa, Iowa City, IA 52242, USA
  • 3Wisconsin State Laboratory of Hygiene, 2601 Agriculture Drive, Madison, WI 53718, USA
  • 4Environmental Chemistry and Technology Program, 660 North Park St, University of Wisconsin, Madison, WI 53706, USA
  • 5US EPA, Office of Research & Development, Las Vegas, NV 89193, USA
  • 6Public Policy Center, University of Iowa, 223 South Quadrangle, Iowa City, IA 52242, USA
  • 7TNO, Princetonlaan 6, 3584 CB Utrecht, the Netherlands
  • 8Decision and Information Sciences Division, Argonne National Laboratory, Argonne, IL, USA
  • 9European Commission, Joint Research Centre, IES, 21027 Ispra, Italy
  • 10National Center for Atmospheric Research, Boulder, CO, USA
  • 11US EPA, Office of Radiation and Indoor Air, Las Vegas, NV 89193, USA
  • 12Institute of Atmospheric Physics, 109017 Moscow, Russia
  • 13Kyrgyz-Russian Slavic University, 44 Kievskaya Str., Bishkek 720000, Kyrgyzstan
  • 14ARIANET, via Gilino 9, 20128 Milan, Italy
  • *now at: California Air Resources Board, Sacramento, CA, USA
  • **now at: Multiphase Chemistry Department, Max Planck Institute for Chemistry, 55128 Mainz, Germany
  • ***now at: International Centre for Integrated Mountain Development (ICIMOD), GPO Box 3226, Kathmandu, Nepal
  • ****now at: US EPA, Atmospheric Modeling and Analysis Division, Research Triangle Park, NC, USA

Abstract. Particulate matter (PM) mass concentrations, seasonal cycles, source sector, and source region contributions in Central Asia (CA) are analyzed for the period April 2008–July 2009 using the Sulfur Transport and dEposition Model (STEM) chemical transport model and modeled meteorology from the Weather Research and Forecasting (WRF) model. Predicted aerosol optical depth (AOD) values (annual mean value ~0.2) in CA vary seasonally, with lowest values in the winter. Surface PM2.5 concentrations (annual mean value ~10 μg m−3) also exhibit a seasonal cycle, with peak values and largest variability in the spring/summer, and lowest values and variability in the winter (hourly values from 2 to 90 μg m−3). Surface concentrations of black carbon (BC) (mean value ~0.1 μg m−3) show peak values in the winter. The simulated values are compared to surface measurements of AOD as well as PM2.5, PM10, BC, and organic carbon (OC) mass concentrations at two regional sites in Kyrgyzstan (Lidar Station Teplokluchenka (LST) and Bishkek). The predicted values of AOD and PM mass concentrations and their seasonal cycles are fairly well captured. The carbonaceous aerosols are underpredicted in winter, and analysis suggests that the winter heating emissions are underestimated in the current inventory.

Dust, from sources within and outside CA, is a significant component of the PM mass and drives the seasonal cycles of PM and AOD. On an annual basis, the power and industrial sectors are found to be the most important contributors to the anthropogenic portion of PM2.5. Residential combustion and transportation are shown to be the most important sectors for BC. Biomass burning within and outside the region also contributes to elevated PM and BC concentrations. The analysis of the transport pathways and the variations in particulate matter mass and composition in CA demonstrates that this region is strategically located to characterize regional and intercontinental transport of pollutants. Aerosols at these sites are shown to reflect dust, biomass burning, and anthropogenic sources from Europe; South, East, and Central Asia; and Russia depending on the time period.

Simulations for a reference 2030 emission scenario based on pollution abatement measures already committed to in current legislation show that PM2.5 and BC concentrations in the region increase, with BC growing more than PM2.5 on a relative basis. This suggests that both the health impacts and the climate warming associated with these particles may increase over the next decades unless additional control measures are taken. The importance of observations in CA to help characterize the changes that are rapidly taking place in the region are discussed.

Short summary
This study presents a regional-scale modeling analysis of aerosols in the Central Asia region including detailed characterization of seasonal source region and sector contributions along with the predicted changes in distribution of aerosols using 2030 future emission scenarios. The influence of long transport and impact of varied emission sources including dust, biomass burning, and anthropogenic sources on the regional aerosol distributions and the associated transport pathways are discussed.
Final-revised paper