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A Numerical Examination of ¹⁴CO₂ Chamber Methodologies for Sampling at the Soil Surface

ScholarsArchive at Oregon State University

Field Value
Title A Numerical Examination of ¹⁴CO₂ Chamber Methodologies for Sampling at the Soil Surface
Names Egan, Jocelyn (creator)
Nickerson, Nick (creator)
Phillips, Claire (creator)
Risk, Dave (creator)
Date Issued 2014 (iso8601)
Note This is the publisher’s final pdf. The published article is copyrighted by the Arizona Board of Regents on behalf of the University of Arizona and can be found at: https://journals.uair.arizona.edu/index.php/radiocarbon/index.
Abstract Radiocarbon is an exceptionally useful tool for studying soil-respired CO₂, providing information about soil
carbon turnover rates, depths of production, and the biological sources of production through partitioning. Unfortunately, little
work has been done to thoroughly investigate the possibility of inherent biases present in current measurement techniques,
like those present in δ¹³CO₂ methodologies, caused by disturbances to the soil’s natural diffusive regime. This study investigates
the degree of bias present in four ¹⁴C sampling chamber methods using a three-dimensional numerical soil-atmosphere
CO₂ diffusion model. The four chambers were tested in an idealized, surrogate reality by assessing measurement bias with
varying Δ¹⁴C and δ¹³C signatures of production, collar lengths, soil biological productivity rates, and soil diffusivities. The
static and Iso-FD chambers showed almost no isotopic measurement bias, significantly outperforming dynamic chambers,
which demonstrated biases up to 200‰ in some modeled scenarios. The study also showed that ¹³C and ¹⁴C diffusive fractionation
are not a constant multiple of one another, but that the δ¹³C correction still works in diffusive scenarios because the
change in fractionation is not large enough to impact measured Δ¹⁴C values during chamber equilibration.
Genre Article
Access Condition http://creativecommons.org/licenses/by/3.0/us/
Identifier Egan, J., Nickerson, N., Phillips, C., & Risk, D. (2014). A Numerical Examination of ¹⁴CO₂ Chamber Methodologies for Sampling at the Soil Surface. Radiocarbon, 56(3), 1175-1188. doi:10.2458/56.17771

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