8 Altered carbon turnover processes and microbiome

8 Altered carbon turnover processes and microbiomes in soils under long-term extremely high CO2 exposure.Alteredcarbonturnoverprocessesandmicrobiomesinsoilsunderlong-termextremelyhighCO2exposureFelixBeulig1,TimUrich2,3,MartinNowak4,SusanE.Trumbore4,GerdGleixner4,GregorD.Gilfillan5,KristineE.Fjelland5andKirstenKüsel1,6*Thereisonlylimitedunderstandingoftheimpactofhighp(CO2)onsoilbiomes.Wehavestudiedafloodplainwetlandwherelong-termemanationsoftemperatevolcanicCO2(mofettes)areassociatedwithaccumulationofcarbonfromtheEarth’smantle.Withanintegratedapproachusingisotopegeochemistry,soilactivitymeasurementsandmulti-omicsanalyses,wedemonstratethathigh(nearlypure)CO2concentrationshavestronglyaffectedpathwaysofcarbonproductionanddecompositionandthereforecarbonturnover.Inparticular,apromotionofdarkCO2fixationsignificantlyincreasedtheinputofgeogeniccarboninthemofettewhencomparedtoareferencewetlandsoilexposedtonormallevelsofCO2.Radiocarbonanalysisrevealedthathighquantitiesofmofettesoilcarbonoriginate