HR: 1340h
AN: A53C-0906    [Abstracts]
TI: Observations and Preliminary Interpretation of Hydrogen Peroxide (H$_{2}$O$_{2}$) and Peroxyacetic Acid (PAA) in the Atmosphere During INTEX-NA, Summer 2004.
AU: * Crounse, J D
EM: crounjd@caltech.edu
AF: California Institute of Technology, MC 150-21 1200 E. California Blvd., Pasadena, CA 91125 United States
AU: Kwan, A J
EM: kwan@its.caltech.edu
AF: California Institute of Technology, MC 150-21 1200 E. California Blvd., Pasadena, CA 91125 United States
AU: Wennberg, P O
EM: wennberg@gps.caltech.edu
AF: California Institute of Technology, MC 150-21 1200 E. California Blvd., Pasadena, CA 91125 United States
AU: O'Sullivan, D W
EM: osulliva@usna.edu
AF: United States Naval Academy, 572 Holloway Rd., Annapolis, MD 21402-5026 United States
AU: Snow, J A
EM: julie.snow@sru.edu
AF: Slippery Rock University, 1 Morrow Way, Slippery Rock, PA 16057 United States
AU: Shen, H
EM: hshen@gso.uri.edu
AF: University of Rhode Island, South Ferry Road, Narragansett, RI 02882-1197 United States
AU: Heikes, B G
EM: bheikes@gso.uri.edu
AF: University of Rhode Island, South Ferry Road, Narragansett, RI 02882-1197 United States
AB: Observations of hydrogen peroxide (H$_{2}$O$_{2}$) and peroxyacetic acid (CH$_{3}$C(O)OOH, PAA) in the troposphere will be reported with an emphasis on PAA. Measurements were made by the Caltech chemical ionization mass spectrometer (CIMS) and by the University of Rhode Island HPLC-Fluorescence instrument. Both were flown on the NASA DC-8 aircraft during the Intercontinental Chemical Transport Experiment - North America (INTEX-NA) science campaign (summer 2004). PAA, heretofore unquantified in the troposphere, was observed in significant concentrations throughout the middle and upper troposphere during INTEX-NA. The primary production mechanism for PAA is the addition of the perhydroxyl (HO$_{2}$) radical to the peracetyl (CH$_{3}$C(O)OO) radical. This mechanism is in direct competition with NO$_{2}$ addition to peracetyl which produces PAN. Peracetyl radical is formed initially through the oxidation of hydrocarbons and can be regenerated through the decomposition of PAN. The presence of PAA may indicate one of two situations: 1) relatively low NO$_{x}$ to high hydrocarbon photochemical environment, or 2) relatively low NO$_{x}$ to high PAN photochemical environment. The loss mechanisms for PAA in the troposphere are not fully understood. Photolysis rates measured in the lab give PAA a lifetime on the order of 3-4 weeks for mid-latitude summertime conditions (Orlando, et. al., 2003). The lifetime of PAA with respect to oxidation by OH has not been measured, but is estimated to be on the order of 1 week, based on measured OH reaction rates with similar species. Unlike PAN, PAA is not expected to decompose at warm temperatures. Wet and dry deposition rates are not known for PAA. The Henry's law coefficient has been determined, K$_{H}$ = 840 M/atm at 298 K (O'Sullivan, et. al, 1996), and shows depositional loss to be of minor importance. The observations will be compared to values inferred from theoretical production/loss mechanisms.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0340 Middle atmosphere--composition and chemistry
DE: 0341 Middle atmosphere--constituent transport and chemistry (3334)
DE: 0365 Troposphere--composition and chemistry
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting