Our research group has been monitoring the microbial diversity in the different available deep wells in the basalt hosted aquifers of Hellisheidi (SW Iceland) since 2008, using bacterial and archaeal 16s rRNA gene cloning, 454-pyrosequencing (hypervariable regions V1-V3) and qPCR. The Hellisheidi site has different strategically located wells, used by Reykjavik Energy, the operator of the associated geothermal plant that has been performing CO2
S injections at a depth of 400–800 m and temperatures up to ~80°C as mitigation strategy for its main waste products. It provides the unique opportunity to benefit from a large-scale injection experiment mimicking natural processes. The basaltic injection site can accordingly be seen as an observatory of the oceanic crust that encounters similar CO2
S-rich fluid percolation, over larger periods of time. Preliminary results suggest that there is a diverse and abundant community that changes drastically after the gas injections. The increase of autotrophic microbial groups after the first injection suggests an enhancement of C fixation, and therefore, consequences for the nutrients cycling in this system. With this project we aim to better understand the microbial communities function and response to pure CO2
S injections in relation to C, S, and N cycles through metagenomics analysis.