Acidic species and chloride depletion in coarse aerosol particles in the US east coast

Yunliang Zhao, Yuan Gao

Research output: Contribution to journalArticlepeer-review

52 Scopus citations

Abstract

To investigate the interactions of water-soluble acidic species associated with coarse mode aerosol particles (1.8-10 μm) and chlorine depletion, ten sets of size-segregated aerosol samples were collected by a 10-stage Micro-Orifice Uniform Deposit Impactor (MOUDI) in Newark, New Jersey on the U.S. east coast. The samples were grouped into two categories according to the air-mass back trajectories and mass ratios of sodium to magnesium and calcium: Group I was primarily impacted by marine air mass and Group II was dominated by the continental air mass. In Group I, the concentrations of coarse mode nitrate and chloride depletion showed a strong correlation (R2 = 0.88). Without considering other cations, nitrate was found to account for all of the chloride depletion in coarse particles for most samples. The association of coarse mode nitrate with sea-salt particles is favored when the mass ratio of sodium to calcium is approximately equal to or greater than unity. Excess sulfate accounts for a maximum of 33% of chloride depletion in the coarse particles. Regarding chloride depletion in the different particle sizes, excess nitrate and sulfate account for 89% of the chloride depletion in the particle size range of 1.8-3.2 μm in the sample from July 13-14; all of the determined dicarboxylic acids and mono-carboxylic acids cannot compensate for the rest of the chloride depletion. In Group II, high percentages of chloride depletion were not observed. With nitrate being dominant in chlorine depletion observed at this location, N-containing species from pollution emissions may have profound impact on atmospheric composition through altering chlorine chemistry in this region.

Original languageEnglish (US)
Pages (from-to)541-547
Number of pages7
JournalScience of the Total Environment
Volume407
Issue number1
DOIs
StatePublished - Dec 15 2008

All Science Journal Classification (ASJC) codes

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution

Keywords

  • Chloride depletion
  • Coarse mode particles
  • Nitrate
  • Water-soluble organic acids

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