HR: 1330h
AN: A32A-0130    [PDF]
TI: NO emissions from arid ecosystems: first results from desert soils of Namibia
AU: * Meixner, F X
EM: meixner@mpch-mainz.mpg.de
AF: Max Planck Institute for Chemistry, Biogeochemistry Departement, J.J.v. Becherweg 27, Mainz, 55128 Germany
AU: Ashuri, F
EM: ashuri@mpch-mainz.mpg.de
AF: Max Planck Institute for Chemistry, Biogeochemistry Departement, J.J.v. Becherweg 27, Mainz, 55128 Germany
AU: Kirkman, G A
EM: grant.kirkman@greenersolutions.com
AF: Max Planck Institute for Chemistry, Biogeochemistry Departement, J.J.v. Becherweg 27, Mainz, 55128 Germany
AU: Trebs, I
EM: ivonne@mpch-mainz.mpg.de
AF: Max Planck Institute for Chemistry, Biogeochemistry Departement, J.J.v. Becherweg 27, Mainz, 55128 Germany
AB: Very recently it becomes evident, that arid and semi-arid soils may be a significant source of nitrogen oxide. As for most other soils, NO emission seems to be controlled by the availability of nitrogen containing nutrients and of soil water. Particularly, desert soils may provide rather high NO emissions just after seasonally limited and/or sporadical rain events due to the accumulation of nitrate and/or ammonium. We like to present some results of NO emission from desert soils which we have obtained through laboratory studies (and subsequent upscaling by a modified Galbally-Johansson algorithm) on soil samples from Namibia. Samples were taken in September/October 2001 between 18.55 - 24.43$^{o}$S, 15.02 -16.29$^{o}$E, and 464 - 1132 m a.s.l. We simultaneously determined NO production and NO consumption rates of the soil samples at different soil temperatures (25 and 35$^{o}$C) and for an appropriate range of soil moisture (dry to field capacity). NO production and consumption rates for dry soils are always close to the detection limit of our method (0.01 ng kg$^{-1}$ s$^{-1}$ and 10$^{-5}$ m$^{3}$ kg$^{-1}$ s$^{-1}$, respectively), while wetting of the samples led to NO production rates up to 11 ng s$^{-1}$ per kg of dry soil. We also determined soil nitrate and ammonium, as well as pH of the soil samples to put variation of rates and fluxes into context. Based on available climatological (soil temperature, rain) and soil chemical data, an attempt is made to estimate the contribution of Namibian desert soils to the regional budget of southern African emissions of NO$_{x}$.
DE: 0315 Biosphere/atmosphere interactions
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting