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Model Simulated Source Contributions to PM2.5 in Santiago and in the Central Region of Chile

Category: Air Pollution Modeling

Accepted Manuscripts
DOI: 10.4209/aaqr.2019.08.0374
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To cite this article:
Langner, J., Gidhagen, L., Bergström, R., Gramsch, E., Oyola, P., Reyes, F., Segersson, D. and Aguilera, C. (2020). Model Simulated Source Contributions to PM2.5 in Santiago and in the Central Region of Chile. Aerosol Air Qual. Res., doi: 10.4209/aaqr.2019.08.0374.

Joakim Langner 1, Lars Gidhagen1, Robert Bergström1,2, Ernesto Gramsch3, Pedro Oyola4, Felipe Reyes4, David Segersson1, Claudio Aguilera4

  • 1 Swedish Meteorological and Hydrological Institute, Norrköping, 60176, Sweden
  • 2 Department of Space, Earth and Environment, Chalmers University of Technology, 41296, Göteborg, Sweden
  • 3 University of Santiago de Chile, Libertador Bernardo O'Higgins, 3363, Santiago, Chile
  • 4 Centro Mario Molina Chile, Santiago, 7510121, Chile

Highlights

  • PM2.5 over central Chile has been simulated with available emission inventories.
  • Simulated mean PM2.5 is generally underestimated at stations in Santiago.
  • Emissions of PM2.5 and semi- and intermediately-volatile organics may be too low.
  • Transport and machinery dominate Santiago PM2.5, wood combustion in other urban areas.
  • Secondary inorganic aerosol is the largest aerosol component outside urban areas.

Abstract

Contributions to PM2.5 from different emission sectors over central Chile and the Santiago metropolitan area during summer/fall and winter have been studied using a chemistry transport model. Simulated mean concentrations of PM2.5 are generally underestimated when compared to measurement stations in Santiago forming part of the Chilean National Air Quality Information System (SINCA). Reasons for this could include underestimated direct PM2.5 emissions; missing emissions of semi- and intermediately-volatile organic compounds, SVOC and IVOC; and too high wind speeds in the simulations. Simulated PM2.5 concentrations in Santiago in winter are lower than observed during night-time and higher during daytime and late evening which can be related to too high simulated wind speeds, as well as to uncertainties in the diurnal variation of the emissions. In summer the diurnal variation is closer to the observed, but the peak concentrations in the mornings are underestimated, and concentrations in the evening are overestimated. Simulated contributions from different aerosol components to PM2.5 at one station in Santiago are lower than observed for all components except for elemental carbon equivalent black carbon, BCe, for which simulated concentrations are comparable or higher than observed. The absolute differences are largest for total organic matter and relative differences are largest for BCe and ammonia. Simulated sector contributions show that emissions from transport and construction machinery dominate in Santiago while residential wood combustion dominates in other urban areas in central Chile except close to major point sources. Secondary inorganic aerosol is estimated to be the largest aerosol component away from urban areas, traffic routes and major industrial sources, while modelled secondary organic aerosol gives a small contribution.

Keywords

Secondary aerosol formation modeling Urban Chemical composition


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