Are the hydrophobic membrane tubes suitable for instantaneous soil CO_2 concentration measurements?

摘要

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 (R) 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.