Testing a simple and low-cost method for long-term (baseline) CO2 monitoring in the shallow subsurface.

Implementation of geological CO 2 storage requires monitoring for potential leakage, with an essential part being establishment of baseline CO 2 in soil gas. CO 2 concentrations and weather parameters were monitored for ∼2 years at three locations in the Netherlands. CO 2 concentrations in soil ranged from 0.1 to 28% and were variable with site, depth and soil type. Statistical models (based on weather parameters) corresponded well with the measured CO 2 time-series, having best fit with soil temperature. This method can detect large CO 2 anomalies, however not smaller leakages. The monitoring method is robust and low-maintenance, making it a relatively low-cost surveillance possibility. [ABSTRACT FROM AUTHOR]