Measurement of advective soil gas flux: results of field and laboratory experiments with CO2

Amonette, James E.; Barr, Jonathan L.; Erikson, Rebecca L.; Dobeck, L.; Barr, J. L.; Shaw, Joseph A.

doi:10.1007/s12665-013-2259-5

Cited by 4 publications

(1 citation statement)

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“…Studies indicated a modification of soil gas transport under chambers used for soil flux measurements [22][23][24]. However, recent results from field studies report both positive and negative correlations between measured soil gas efflux and near-surface turbulence [13,[25][26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Air Pressure Fluctuations and Topsoil Gas Concentrations within a Scots Pine Forest

et al. 2016

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High-precision differential air pressure measurements were conducted in the below-canopy space of a Scots pine forest and in the forest soil to investigate small air pressure fluctuations and their effect on soil gas flux. In addition to air pressure measurements, tracer gas concentration in the soil and airflow characteristics above and below the canopy were measured. Results suggest that air pressure fluctuations in the frequency range of 0.01 Hz-0.1 Hz are strongly dependent on abovecanopy wind speed. While amplitudes of the observed air pressure fluctuations (<10 Pa) increase significantly with increasing above-canopy wind speed, the periods decrease significantly with increasing above-canopy wind speed. These air pressure fluctuations are associated with the pressure-pumping effect in the soil. A pressure-pumping coefficient was defined, which describes the strength of the pressure-pumping effect. During the measurement period, pressure-pumping coefficients up to 0.44 Pa·s −1 were found. The dependence of the pressure-pumping coefficient on mean above-canopy wind speed can be described well with a polynomial fit of second degree. The knowledge of this relation simplifies the quantification of the pressure-pumping effect in a Scots pine forest considerably, since only the mean above-canopy wind speed has to be measured. In addition, empirical modeling revealed that the pressure-pumping coefficient explains the largest fraction of the variance of tracer gas concentration in the topsoil.

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