Carbonyl sulfide (COS) is a reduced sulfur gas that is taken up irreversibly in plant leaves proportionally with CO2, allowing its potential use as a tracer for gross primary production. Recently,wheat field soil at the Southern Great Plains Atmospheric Radiation Measurement site in Lamont, Oklahoma, was found to be a measureable source of COS to the atmosphere. To understand the mechanism of COS production, soil and root samples were collected from the site and incubated in the laboratory over a range of temperatures (15–34 C) and light conditions (light and dark). Samples exhibited mostly COS net uptake from the atmosphere in dark and cool (<22–25 C) trials. COS emission was observed during dark incubations at high temperatures (>25 C), consistent with field observations, and at a lower temperature (19 C) when a full spectrum lamp (max wavelength 600 nm) was applied. Sterilized soil and root samples yielded only COS production that increased with temperature, supporting the hypothesis that (a) COS production in thesesamples is abiotic, (b) production is directly influenced by temperature and light, and (c) some COS consumption in soil and root samples is biotic.
We would like to thank S. Biraud for sample collection, M. Torn, U. Seibt, K. Maseyk, J.E. Campbell, and J. Berry for excellent suggestions, A. Kornfeld for the light intensity measurement, and C. Harth, J. Mühle, and R. Weiss for standard calibration. This work was supported by the NSF EAR/GEO program and the Martin Foundation. Data presented in this work can be found in the UC3 archival system Merritt data repository, at http://n2t.net/ark:/13030/m51g217t, with doi:10.6071/H8RN35SM.