HR: 1330h
AN: A32A-0131    [PDF]
TI: A Method for the Measurement of Nitrous Acid Flux Using Relaxed Eddy Accumulation
AU: * Bertman, S
EM: bertman@wmich.edu
AF: Western Michigan University, Department of Chemistry, Kalamazoo, MI 49008 United States
AU: Marchewka, M
EM: marchewka7@yahoo.com
AF: Western Michigan University, Department of Chemistry, Kalamazoo, MI 49008 United States
AU: King, J
EM: s0king@unix.cc.wmich.edu
AF: Western Michigan University, Department of Chemistry, Kalamazoo, MI 49008 United States
AB: HONO has recently received renewed attention as a byproduct of condensed nitrogen photolysis and as a potential atmospheric radical source. In particular, several recent accounts suggesting a photochemical source in forests have lead us to develop a method for assessing nitrous acid flux above a hardwood forest in northern Michigan. The technique was based on nitrous acid in ambient air being scrubbed into a 1mM phosphate buffer that was then derivatized into a light absorbing complex. A separate scrubbing system was used for updrafts and downdrafts after the air had been separated through Teflon valves according to input from a sonic anemometer. The detection of the complex was performed via UV absorption through a capillary flowthrough cell. Detection limit for this analytical method is around 10 pptv. Derivatized solution from each flow system was injected into the capillary cell via an 8-port valve with two sample loops. Each sample loop was injected as soon as it filled, which allowed measurement of all of the scrubbed material in each flow system. Laboratory tests were performed to assess the accuracy and suitability of this method. The field worthiness of the instrument was determined during the summer of 2003 at the University of Michigan Biological Station in northern Michigan where it was placed on top of a 35m tower above a forest canopy.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0315 Biosphere/atmosphere interactions
DE: 0365 Troposphere--composition and chemistry
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting