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Portable Automation of Static Chamber Sample Collection for Quantifying Soil Gas Flux
Author(s) -
Davis Morgan P.,
Groh Tyler A.,
Parkin Timothy B.,
Williams Ryan J.,
Isenhart Thomas M.,
Hofmockel Kirsten S.
Publication year - 2018
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2017.10.0387
Subject(s) - environmental science , sample (material) , automation , flux (metallurgy) , materials science , engineering , chromatography , chemistry , mechanical engineering , metallurgy
Quantification of soil gas flux using the static chamber method is labor intensive. The number of chambers that can be sampled is limited by the spacing between chambers and the availability of trained research technicians. An automated system for collecting gas samples from chambers in the field would eliminate the need for personnel to return to the chamber during a flux measurement period and would allow a single technician to sample multiple chambers simultaneously. This study describes C hamber A utomated S ampling E quipment (Flux CASE ) to collect and store chamber headspace gas samples at assigned time points for the measurement of soil gas flux. The FluxCASE design and operation is described, and the accuracy and precision of the FluxCASE system is evaluated. In laboratory measurements of nitrous oxide (N 2 O), carbon dioxide (CO 2 ), and methane (CH 4 ) concentrations of a standardized gas mixture, coefficients of variation associated with automated and manual sample collection were comparable, indicating no loss of precision. In the field, soil gas fluxes measured from FluxCASEs were in agreement with manual sampling for both N 2 O and CO 2 . Slopes of regression equations were 1.01 for CO 2 and 0.97 for N 2 O. The 95% confidence limits of the slopes of the regression lines included the value of one, indicating no bias. Additionally, an expense analysis found a cost recovery ranging from 0.6 to 2.2 yr. Implementing the FluxCASE system is an alternative to improve the efficiency of the static chamber method for measuring soil gas flux while maintaining the accuracy and precision of manual sampling. Core Ideas FluxCASEs automate collection of gas samples from static chambers, reducing labor costs. FluxCASEs maintain accuracy and precision observed under manual sampling. Automated sample collection increases coverage of spatial variability in soils.