A cost-effective method for reducing soil disturbance-induced errors in static chamber measurement of wetland methane emissions
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Static chambers used for sampling methane (CH4) in wetlands are highly sensitive to soil disturbance. Temporary compression around chambers during sampling can inflate the initial chamber CH4 headspace concentration and/or lead to generation of non-linear, unreliable flux estimates that must be discarded. In this study, we tested an often-used rubber gasket (RG)-sealed static chamber against a water-filled gutter (WFG) seal design that could be set up and sampled from a distance of 2 m with a newly designed remote rod sampling system to reduce soil disturbance. Compared to conventional RG design, our remotely sampled static chambers reduced the chance of detecting inflated initial CH4 concentrations (>3.6 ppm) from 66 to 6 % and nearly doubled the proportion of robust linear regressions (r 2 > 0.9) from 45 to 86 %. Importantly, the remote rod sampling system allows for more accurate and reliable CH4 sampling without costly boardwalk construction. This paper presents results demonstrating that the remote rod sampling system combined with WFG static chambers improves CH4 data reliability by reducing initial gas measurement variability due to chamber disturbance when tested on a mineral soil-restored wetland in Charles City County, Virginia, USA.
KeywordsGas flux Greenhouse gas Methane Static chamber Wetland
We acknowledge the help of Jonathan Bills, who provided critical assistance with site instrumentation and field sampling. Hongjun Wang and Wes Willis assisted with configuration and maintenance of the gas chromatograph. Hongjun Wang, Ashley Helton, and Emily Bernhardt gave valuable advice and training in static chamber design and gas sampling and Todd Smith assisted with chamber construction. James Perry, Lee Daniels, David Bailey, and Leo Snead provided valuable insight into the site history and scope of previous investigations. We thank Ann and Jay Kinney for graciously allowing us to use of their driveway to access the site. Three anonymous reviewers provided helpful comments that improved this manuscript.
This work was funded by the Peterson Family Foundation, Wetland Studies and Solutions Inc. and the Duke University Wetland Center Endowment.
Compliance with Ethical Standards
Conflict of Interest
We declare no conflict of interest.
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