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Vuillemin, Aurèle; Ariztegui, Daniel; Mayr, Christoph; Lücke, Andreas (2013): Geomicrobiology, bulk sediment characteristics and pore water chemistry of sediment cores from Laguna Potrok Aike, southern Patagonia. PANGAEA, https://doi.org/10.1594/PANGAEA.811524, Supplement to: Vuillemin, Aurèle; Ariztegui, Daniel; De Coninck, Arnaud S; Lücke, Andreas; Mayr, Christoph; Schubert, Carsten J; PASADO Science Team (2013): Origin and significance of diagenetic concretions in sediments of Laguna Potrok Aike, southern Argentina. Journal of Paleolimnology, 50, 275-291, https://doi.org/10.1007/s10933-013-9723-9

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Abstract:
Authigenic minerals can form in the water column and sediments of lakes, either abiotically or mediated by biological activity. Such minerals have been used as paleosalinity and paleoproductivity indicators and reflect trophic state and early diagenetic conditions. They are also considered potential indicators of past and perhaps ongoing microbial activity within sediments. Authigenic concretions, including vivianite, were described in late glacial sediments of Laguna Potrok Aike, a maar lake in southernmost Argentina. Occurrence of iron phosphate implies specific phosphorus sorption behavior and a reducing environment, with methane present. Because organic matter content in these sediments was generally low during glacial times, there must have been alternative sources of phosphorus and biogenic methane. Identifying these sources can help define past trophic state of the lake and diagenetic processes in the sediments. We used scanning electron microscopy, phosphorus speciation in bulk sediment, pore water analyses, in situ ATP measurements, microbial cell counts, and measurements of methane content and its carbon isotope composition (d13C CH4) to identify components of and processes in the sediment. The multiple approaches indicated that volcanic materials in the catchment are important suppliers of iron, sulfur and phosphorus. These elements influence primary productivity and play a role in microbial metabolism during early diagenesis. Authigenic processes led to the formation of pyrite framboids and revealed sulfate reduction. Anaerobic oxidation of methane and shifts in pore water ion concentration indicated microbial influence with depth. This study documents the presence of active microbes within the sediments and their relationship to changing environmental conditions. It also illustrates the substantial role played by microbes in the formation of Laguna Potrok Aike concretions. Thus, authigenic minerals can be used as biosignatures in these late Pleistocene maar sediments.
Further details:
Vuillemin, Aurèle; Ariztegui, Daniel; Lücke, Andreas; Mayr, Christoph; PASADO Science Team (2013): Paleoenvironmental conditions define current sustainability of microbial populations in Laguna Potrok Aike sediments, Argentina. Aquatic Sciences, https://doi.org/10.1007/s00027-013-0317-4
Vuillemin, Aurèle; Ariztegui, Daniel; Nobbe, G; Schubert, Carsten J; PASADO Science Team (2013): Influence of methanogenic populations in Holocene lacustrine sediments revealed by clone libraries and fatty acid biogeochemistry. Geomicrobiology Journal, 50(3), 275-291, https://doi.org/10.1080/01490451.2013.824050
Vuillemin, Aurèle; Ariztegui, Daniel; Vasconcelos, Crisogono; PASADO Science Team (2010): Establishing sampling procedures in lake cores for subsurface biosphere studies: Assessing in situ microbial activity. Scientific Drilling, 10, 35-39, https://doi.org/10.2204/iodp.sd.10.04.2010
Coverage:
Latitude: -51.964600 * Longitude: -70.377200
Comment:
This study was financially and logistically supported by ICDP, Swiss National Science Foundation (Grant 200020-119931/2 to D. Ariztegui), University of Geneva, University of Bremen, Deutsche Forschungsgemeinschaft, Eawag, Natural Sciences and Engineering Research Council of Canada, University of Buenos Aires, Secretaria de Ciencia y Tecnologia of Cordoba, Vetenskapsrädet of Sweden.
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