title: In situ soil COS exchange of a temperate mountain grassland under simulated drought.
abstract: During recent years, carbonyl sulfide (COS), a trace gas with a similar diffusion pathway into leaves as carbon dioxide (CO2), but with no known "respiration-like" leaf source, has been discussed as a promising new approach for partitioning net ecosystem-scale CO2fluxes into photosynthesis and respiration. The utility of COS for flux partitioning at the ecosystem scale critically depends on the understanding of non-leaf sources and sinks of COS. This study assessed the contribution of the soil to ecosystem-scale COS fluxes under simulated drought conditions at temperate grassland in the Central Alps. We used transparent steady-state flow-through chambers connected to a quantum cascade laser spectrometer to measure the COS and CO2gas exchange between the soil surface and the atmosphere. Soils were a source of COS during the day, emissions being mainly driven by incoming solar radiation and to a lesser degree soil temperature. Soil water content had a negligible influence on soil COS exchange and thus the drought and control treatment were statistically not significantly different. Overall, daytime fluxes were large (12.5 ± 13.8 pmol m-2s-1) in their magnitude and consistently positive compared to the previous studies, which predominantly used dark chambers. Nighttime measurements revealed soil COS fluxes around zero, as did measurements with darkened soil chambers during daytime reinforcing the importance of incoming solar radiation. Our results suggest that abiotic drivers play a key role in controlling in situ soil COS fluxes of the investigated grassland.
authors.affiliation: Institute of Ecology, University of Innsbruck, Sternwartestrasse 15, Tyrol, Austria. Florian.Kitz@student.uibk.ac.at.
authors.forename: Florian
authors.identifier: 0000-0002-3363-0485
authors.initials: F
authors.lastname: Kitz
authors.affiliation: Institute of Ecology, University of Innsbruck, Sternwartestrasse 15, Tyrol, Austria.
authors.forename: Katharina
authors.initials: K
authors.lastname: Gerdel
authors.affiliation: Institute of Ecology, University of Innsbruck, Sternwartestrasse 15, Tyrol, Austria.
authors.forename: Albin
authors.initials: A
authors.lastname: Hammerle
authors.affiliation: Institute of Ecology, University of Innsbruck, Sternwartestrasse 15, Tyrol, Austria.
authors.forename: Tamara
authors.initials: T
authors.lastname: Laterza
authors.affiliation: Institute of Ecology, University of Innsbruck, Sternwartestrasse 15, Tyrol, Austria.
authors.forename: Felix M
authors.initials: FM
authors.lastname: Spielmann
authors.affiliation: Institute of Ecology, University of Innsbruck, Sternwartestrasse 15, Tyrol, Austria.
authors.forename: Georg
authors.initials: G
authors.lastname: Wohlfahrt
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D055864:Droughts; D017753:Ecosystem; D065948:Grassland; D012987:Soil
chemical_list: D012987:Soil; D002245:Carbon Dioxide
keywords: Abiotic degradation; Carbonyl sulfide; Flux partitioning; Microbial activity; Photodegradation