D2O SIP (Hainich CZO H41)

Microbial life in oligotrophic groundwater ecosystems is fuelled by two major processes: the autochthonous production of biomass by chemolithoautotrophy and the introduction of allochthonous material from the surface. Here, we employed heavy water (D2O) labeling microcosm experiments to investigate the response of a groundwater microbial community to two allochthonous model carbon sources, veratric acid and methylamine. The groundwater used was derived from well H41 of the Hainich Critical Zone Exploratory (CZE), a platform to study the links between surface and subsurface biogeosphere, located in carbonate and marlstone rocks in central Germany. Groundwater from this well is oxic, with a pH of 7.2, and the infiltration area of the corresponding aquifer assemblage is located in a forest area.