HR: 0800h
AN: A41C-11    [Abstracts]
TI: Chemical and Isotopic Characterization of Rainwater Dissolved Organic Carbon and Chromophoric Dissolved Organic Matter
AU: * Avery, G B
EM: averyg@uncw.edu
AF: University of North Carolina Wilmington, 601 S College Rd, Wilmington, NC 28403-5932, United States
AU: Kieber, R J
EM: kieberr@uncw.edu
AF: University of North Carolina Wilmington, 601 S College Rd, Wilmington, NC 28403-5932, United States
AU: Willey, J D
EM: willeyj@uncw.edu
AF: University of North Carolina Wilmington, 601 S College Rd, Wilmington, NC 28403-5932, United States
AU: Seaton, P J
EM: seatonp@uncw.edu
AF: University of North Carolina Wilmington, 601 S College Rd, Wilmington, NC 28403-5932, United States
AB: Chromophoric dissolved organic matter (CDOM) is a ubiquitous, integral component of atmospheric waters which comprises a significant fraction of the dissolved organic carbon (DOC) pool in the condensed phase. The presence of significant quantities of highly chromophoric DOM in atmospheric waters has profound ramifications with respect to a wide variety of fundamental processes in atmospheric chemistry because of its impact on solar radiative transfer and its involvement in the oxidizing and acid generating capacity of the troposphere. Initial isotopic characterization (13C, 14C, 15N) of CDOM will be presented which provides information on origin as well as transport and cycling of CDOM though the atmosphere. We have determined 4-24 percent of DOC is of fossil fuel origin and that rain DOC can be terrestrial, marine or a combination of the two depending on air mass back trajectory. The C:N ratio as well as nuclear magnetic resonance 1H-NMR spectra of extracted CDOM from terrestrial and marine origin indicate a relatively continuous and broad distribution of signals, suggesting the presence of complex mixtures of compounds. The DOC concentration of rainwater has decreased approximately 50 percent since 1995. 13C and 14C signatures of rain DOC indicates that in 1997-1998 up to 24 percent of Wilmington rainwater DOC was from fossil fuel origin. Comparison of fossil fuel contributions of CDOM and DOC will help determine what fraction of the loss of rainwater DOC results from changing fossil fuel inputs and what role if any CDOM plays in these changes.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
DE: 1029 Composition of aerosols and dust particles
DE: 3311 Clouds and aerosols
DE: 4801 Aerosols (0305, 4906)
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly