Are the hydrophobic membrane tubes suitable for instantaneous soil CO2 concentration measurements?

Abstract

One technique for measurement of soil CO₂ production and emission is a gradient method using CO₂ concentration measurements within soil by polypropylene membrane tubes (Accurel® PP V8/2 HF). In this study, we determined whether these tubes are suitable for monitoring instantaneous CO₂ concentration and its rapid changes in the soil. The tested tube was placed within the plastic bag. The CO₂ concentration was continuously measured in both the tube and the bag to determine the time lag in CO₂ concentration changes in the tube after an evoked rapid increase in CO₂ concentration in the bag. We found that higher the CO₂ concentration and higher the increase in CO₂ concentration around the tube, the faster is the change in CO₂ concentration within the tube. These relationships were described by hyperbola models and corresponding equations. Our results confirm that the tested membrane tubes are suitable for monitoring rapid changes in soil CO₂ concentration.