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

Abstract

International audienceCO 2 capture and sto rage 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 CO 2 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 N etwork of Excellence “ CO2GeoNet” on a natural CO2 vent at the Laacher See, Germany. The investigation of environmentally important microbial communities in the soil samples show ed significant differences between the CO 2-rich (>90 % of soil gas) , the medium CO 2 (20%) , and the control site with background CO 2 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 CO 2 con centrations. 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 CO 2 fro m deep reservoirs into near-surface terrestrial ecosystems

Developments since 2005 in understanding potential environmental impacts of CO2 leakage from geological storage

“…Studies at natural CO 2 seepage sites have also included direct assessment of impacts on plants and microbes, for example those carried out at Latera Oppermann et al, 2010), Laacher See (Frerichs et al, 2013;Krüger et al, 2011;Krüger et al, 2009) and Florina (Ziogou et al, 2013). The results of these studies are detailed in West et al (In submission).…”

CO2 escapes in the Laacher See region, East Eifel, Germany: Application of natural analogue onshore and offshore geochemical monitoring

“…As said before, the Laacher See site is exposed to the atmosphere only since hundreds of years. Structures and organics layers inherited from underwater stage are still to be found within this soil (Krüger et al, 2009), while soils at Obermendig (sampling on the 27 th of September) have never been affected by such an evolution. Therefore this could partly result in observing similar carbon dioxide contents, especially above gas vents, but different radon levels.…”

“…Leakage and its Impacts" . Under this work package several methods were used, with special emphasize on soil/atmosphere gas monitoring with conventional and newly rapid surveying methods, microbiological impact studies and water column monitoring (Beaubien et al, 2008;Krüger et al, 2009). Here we present results acquired in 2007 and 2008 in the vicinity and within the water body of the Laacher See, a maar lake emplaced in Western Germany near Koblenz.…”

Impacts of Carbon Dioxide Gas Leaks from Geological Storage Sites on Soil Ecology and Above-Ground Vegetation

“…Elevated soil CO 2 concentrations can cause changes in mineralogy composition together with changes in trace elements like As and Cr (Kruger et al, 2009;Stenhouse et al, 2009). Changes in cation exchange capacity (CEC), and the presence of oxides like CaO, MgO, Fe 2 O 3 , and Mn 3 O 4 have also been reported elsewhere (Blake et al, 2000;Billett et al, 1987;Goulding et al, 1998).…”