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High spatial resolution of distribution and interconnections between Fe- and N-redox processes in profundal lake
Emily D Melton1, Peter Stief, Sebastian Behrens
1Geomicrobiology, Center for Applied Geosciences, University of Tübingen, Tübingen, 72076, Germany.
Environmental Microbiology
|July 22, 2014
Summary
Iron and nitrogen cycles in lake sediments are linked. Microbes and chemical reactions connect these essential nutrient cycles, influencing iron cycling within distinct redox zones.
Area of Science:
- Environmental Microbiology
- Biogeochemistry
- Limnology
Background:
- The biogeochemical cycles of iron (Fe) and nitrogen (N) are critical in freshwater ecosystems.
- Understanding their spatial interactions in lake sediments is vital for ecosystem health.
Purpose of the Study:
- To investigate the spatial arrangement and interconnections of nitrogen and iron cycles within profundal lake sediments.
- To identify specific redox zones and microbial communities involved in Fe and N cycling.
Main Methods:
- Measurement of chemical gradients (O2, NO3(-), NH4(+), pH, Eh, Fe(II), Fe(III)).
- Microbial distribution assessment using most probable numbers (MPN) and quantitative polymerase chain reaction (qPCR).
Main Results:
- Defined oxic, denitrification, and iron redox transition zones based on chemical and microbial data.
- Identified nitrate-dependent Fe(II) oxidizers and denitrifiers in the denitrification zone.
- Observed distinct distributions of Fe(II) and Fe(III) with evidence of iron cycling.
Conclusions:
- The Fe and N cycles are biologically linked via nitrate-reducing Fe(II) oxidizers.
- Chemical interactions involving NOx(-) species also connect the cycles.
- Sedimentary redox zonation dictates the interplay between Fe and N biogeochemical processes.
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