Origins of aerosol chlorine during winter over north central Colorado, USA

Details

• Journal Title:
  Journal of Geophysical Research: Atmospheres
• Personal Author:
  Jordan, C. E. ; Pszenny, A. A. P. ; Keene, W. C. ; Cooper, O. R. ; Deegan, B. ; Maben, J. ; Routhier, M. ; Sander, R. ; Young, A. H.
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; ESRL (Earth System Research Laboratory)
• Description:
  The Nitrogen, Aerosol Composition, and Halogens on a Tall Tower campaign (February-March 2011) near Boulder, Colorado, investigated nighttime ClNO2 production and processing. Virtually all particulate Cl was in the form of ionic Cl-. The size distributions of Cl- and Na+ were similar, with most of the mass in the supermicrometer size fraction, suggesting primary sources for both. Median Cl- concentrations were about half those of Na+ and Ca2+ for particle diameters centered at 1.4 and 2.5 mu m. To investigate potential sources of Na+ and Cl-, four cases were studied that featured the prevalence of Na+ and Cl- and different transport pathways based on FLEXible PARTicle dispersion model (FLEXPART) retroplumes. Estimates of supermicrometer Na+ particle lifetime against deposition indicate that long-range transport of marine aerosols could account for the observed Na+. However, measured molar ratios of Ca2+ to Na+ (0.143-0.588) compared to seawater (0.022) indicate significant contributions from crustal sources to the supermicrometer aerosol composition during these four case studies. Further, low molar ratios of Mg2+ to Na+ (0.007-0.098) relative to seawater (0.114) suggest that some of the Na+, and presumably associated Cl-, originated from non-sea-salt sources. The heterogeneous chemical composition of saline soils throughout the western U.S., along with the nonlinearity of wind-driven soil deflation as a function of various surface soil properties, precludes a quantitative apportionment of soil, marine, and anthropogenic sources to the observed coarse-fraction aerosol. Nonetheless, results suggest that deflation of saline soils was a potentially important source of particulate Cl- that sustained atmospheric ClNO2 production and associated impacts on oxidation processes over northern Colorado.
• Source:
  Journal of Geophysical Research-Atmospheres, 120(2), 678-694.
• DOI:
  http://dx.doi.org/10.1002/2014jd022294
• Document Type:
  Journal Article
• Rights Information:
  Other
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha256:83324b29433f65bb17f787ece3a2b983a3bfb195588b40724a0e36bdd1aeb86f
• Download URL:
  https://repository.library.noaa.gov/view/noaa/21649/noaa_21649_DS1.pdf
• File Type:
  [PDF - 1.42 MB ]