A simple CO2 gas analyzing system for soil gas samples

Abstract

This study proposed a simple CO2 gas analyz-ing system for soil gas samples. The system consisted of a portable infrared-sensing CO2 probe with an RS232C-type interface and a personal computer. A free-software was used to collect signal outputs from the probe and store the output data in the computer. The calibration of the system gave a definite linear relationship between the outputs from the system and the actual CO2 concentrations of gas sam-ples. The calibration did not depend on temperature. Ef-fects of the sampling time on the CO2 concentrations were also quantified. Although the measured values linearly de-creased 1 to 2 % due to time-lag between gas sampling and gas analysis, it is possible to correct the measured values if the linear reduction was evaluated in advance.