Impact of Wildfire Emissions on Chloride and Bromide Depletion in Marine Aerosol Particles

Environ Sci Technol. 2017 Aug 15;51(16):9013-9021. doi: 10.1021/acs.est.7b02039. Epub 2017 Jul 27.

Abstract

This work examines particulate chloride (Cl-) and bromide (Br-) depletion in marine aerosol particles influenced by wildfires at a coastal California site in the summers of 2013 and 2016. Chloride exhibited a dominant coarse mode due to sea salt influence, with substantially diminished concentrations during fire periods as compared to nonfire periods. Bromide exhibited a peak in the submicrometer range during fire and nonfire periods, with an additional supermicrometer peak in the latter periods. Chloride and Br- depletions were enhanced during fire periods as compared to nonfire periods. The highest observed %Cl- depletion occurred in the submicrometer range, with maximum values of 98.9% (0.32-0.56 μm) and 85.6% (0.56-1 μm) during fire and nonfire periods, respectively. The highest %Br- depletion occurred in the supermicrometer range during fire and nonfire periods with peak depletion between 1.8-3.2 μm (78.8% and 58.6%, respectively). When accounting for the neutralization of sulfate by ammonium, organic acid particles showed the greatest influence on Cl- depletion in the submicrometer range. These results have implications for aerosol hygroscopicity and radiative forcing in areas with wildfire influence owing to depletion effects on composition.

MeSH terms

  • Aerosols
  • Air Pollutants*
  • Bromides*
  • California
  • Environmental Monitoring
  • Fires
  • Particle Size

Substances

  • Aerosols
  • Air Pollutants
  • Bromides