title: Sampling soil-derived CO2 for analysis of isotopic composition: a comparison of different techniques.
abstract: A new system for soil respiration measurement [P. Rochette, L.B. Flanagan, E.G. Gregorich. Separating soil respiration into plant and soil components using analyses of the natural abundance of carbon-13. Soil Sci. Soc. Am. J., 63, 1207-1213 (1999).] was modified in order to collect soil-derived CO2 for stable isotope analysis. The aim of this study was to assess the suitability of this modified soil respiration system to determine the isotopic composition (delta13C) of soil CO2 efflux and to measure, at the same time, the soil CO2 efflux rate, with the further advantage of collecting only one air sample. A comparison between different methods of air collection from the soil was carried out in a laboratory experiment. Our system, as well as the other dynamic chamber approach tested, appeared to sample the soil CO2, which is enriched with respect to the soil CO2 efflux, probably because of a mass dependent fractionation during diffusion and because of the atmospheric contribution in the upper soil layer. On the contrary, the static accumulation of CO2 into the chamber headspace allows sampling of delta13C-CO2 of soil CO2 efflux.
authors.affiliation: Department of Environmental Sciences, Second University of Naples, Via Vivaldi 43, 81100, Caserta, Italy. teresa.bertolini@unina2.it
authors.forename: Teresa
authors.initials: T
authors.lastname: Bertolini
authors.forename: Ilaria
authors.initials: I
authors.lastname: Inglima
authors.forename: Mauro
authors.initials: M
authors.lastname: Rubino
authors.forename: Fabio
authors.initials: F
authors.lastname: Marzaioli
authors.forename: Carmine
authors.initials: C
authors.lastname: Lubritto
authors.forename: Jens-Arne
authors.initials: JA
authors.lastname: Subke
authors.forename: Alessandro
authors.initials: A
authors.lastname: Peressotti
authors.forename: M Francesca
authors.initials: MF
authors.lastname: Cotrufo
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D002247:Carbon Isotopes / Q000737:chemistry*; D006801:Humans; D015203:Reproducibility of Results; D012987:Soil / Q000032:analysis*; D013055:Spectrophotometry, Infrared / Q000295:instrumentation / Q000379:methods
chemical_list: D002247:Carbon Isotopes; D012987:Soil; D002245:Carbon Dioxide