Figure 9.

Model of possible carbon and iron fluxes in a snottite from the first level. The oxic (grey) and anoxic parts (white) are indicated. Leptospirillum species are solely found in the oxic part, whereas acidithiobacilli are found in the oxic as well as in the anoxic part. The archaea could only be detected in the anoxic zone. In the oxic area, ferrous iron oxidation can take place while in the anoxic part iron reduction by Acidithiobacillus sp. and Ferroplasma sp. is possible. Additionally, the iron can be reduced abiotically via pyrite dissolution (grey arrows). Atmospheric CO₂ fixation could only be detected in the surface area, approximately in the first 30 μm. Behind this point, a possible carbon source could be dissolved H₂CO₃. The inorganic carbon can be fixed by the primary producers like the autotrophic acidithiobacilli and leptospirilla. Heterotrophic organisms like Ferroplasma sp. can use the resulting organic carbon sources to sustain their energy and carbon metabolism. The role of the uncultivated archaea is so far not proven but heterotrophic growth is most likely.