Ecosystem effects of elevated CO2 concentrations on microbial populations at a terrestrial CO2 vent at Laacher See, Germany

CO₂ capture and storage in deep saline aquifers or depleted gas and oil reservoirs offer is one option for reducing greenhouse gas emissions. Our study aims at investigating the environmental impact of CO₂ leakage from deep reservoirs into near-surface terrestrial environmen ts. To understand the effect of unlikely, but potential CO₂ release on such an ecosystem, detailed knowledge on the abundance and diversity of plants and microorganisms is essential. Therefore, an ecosystem study has been conducted within the Network of Excellence “ CO₂GeoNet” on a natural CO₂ vent at the Laacher See, Germany. The investigation of environmentally important microbial communities in the soil samples showed significant differences between the CO₂-rich (>90% of soil gas), the medium CO₂ (20%), and the control site with background CO₂ concentrations. The ecosystem appears to have adapted to the different conditions through species substitution or adaptation, showing a shift towards anaerobic and acidophilic species under elevated CO₂ concentrations. At the end, this study should identify possible candidates in the botanical and microbial kingdoms, whose presence or absence provide easily detectable indicators for the leakage of CO₂ fro m deep reservoirs into near-surface terrestrial ecosystems.