<p>Comparison of CO2, CH4 and N2O soil-atmosphere exchange measured in static chambers with cavity ring-down spectroscopy and gas chromatography</p>

Comparison of CO2, CH4 and N2O soil-atmosphere exchange measured in static chambers with cavity ring-down spectroscopy and gas chromatography

Authors: 
Jesper Riis Christiansena, Josh Outhwaiteb, Sean M. Smuklerb

Agricultural and Forest Meteorology 211–212 (2015) 48–57

Abstract: 

A laboratory and field experiment compared fluxes of CO2, CH4 and N2O measured with cavity ring-downspectroscopy (CRDS) and gas chromatography (GC). The comparison between CRDS and GC showed thataverage CO2 fluxes were significantly higher for CRDS in both the laboratory and field, but the sameexperimental treatments effects were detected for both techniques. Compared to CRDS, the GC techniquewas severely limited in detecting CH4 fluxes in both the laboratory and field. Thus, only 16% of measuredGC fluxes were detectable in the laboratory and none in the field whereas CRDS could detect 65% and97% of the CH4 fluxes in the laboratory and field. In contrast, N2O fluxes measured with CRDS and GCwere not different for both the laboratory and field. It was observed that a lower proportion of N2O fluxescould be detected with CRDS (73%) than GC (92%) in the laboratory and similar recovery (65% and 68%)for the field. Thus, the same treatment effects were observed for both CRDS and GC. Furthermore, thecomparison between CRDS and GC showed that enclosure times as short as 600 s for our field study siteare suitable to estimate the same treatment effects, but not necessarily flux magnitude.Weconclude thatCRDS and GC can provide the same level of information regarding treatment effects in both laboratoryand field experiments for CO2 and N2O, but not for CH4 and it is possible to reduce enclosure time withoutcomprising comparability between the two techniques.