HR: 15:10h
AN: A13F-06    [Abstracts]
TI: Laboratory study of the interaction of HONO with snow in a packed ice bed
AU: * Ammann, M
EM: markus.ammann@psi.ch
AF: Paul Scherrer Institute, Laboratory of Radio- and Environmental Chemistry, Villigen, 5232 Switzerland
AU: Huthwelker, T
EM: Thomas.Huthwelker@psi.ch
AF: Paul Scherrer Institute, Laboratory of Radio- and Environmental Chemistry, Villigen, 5232 Switzerland
AB: Nitrous acid (HONO) is an important intermediate in snowpack photochemistry. Photochemical production of nitrogen oxides from nitrate and other forms of nitrogen in the snowpack can also directly or indirectly lead to HONO, which in turn is an important source of OH radicals above the snowpack. The physical and chemical fate of HONO within the snowpack and its pathways for emission are not clear in detail. Packed ice beds and coated wall flow tubes have been previously used to investigate adsorption properties of a range of trace gases with ice or snow. These experiments usually involve the analysis of a breakthrough curve of the trace gas, to which the ice is exposed, and the derivation of kinetic and equilibrium parameters thereof. We have extended this technique by using radioactively labelled HO¹³NO. From this, we get additional kinetic information about the trace gas-ice interaction. First, by scanning the radioactivity along the flow tube the trace gas distribution along the tube can be observed. Secondly, the amount of radioactive trace gas leaving the ice tube gives a direct information about the residence time of individual molecules due to reversible adsorption on the ice. Using these data with simultaneous measurement of a classical breakthrough allows constraining the uptake mechanism. We demonstrate this new approach to study the trace gas uptake on ice using the uptake of HONO on a packed ice bed and compare the result with numerical modelling.
DE: 0317 Chemical kinetic and photochemical properties
DE: 0365 Troposphere: composition and chemistry
DE: 0368 Troposphere: constituent transport and chemistry
DE: 0736 Snow (1827, 1863)
DE: 1707 Cryosphere
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005