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 environments. 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 "CO(2)GeoNet" 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 from deep reservoirs into near-surface terrestrial ecosystems. (C) 2008 Elsevier Ltd. All rights reserved.