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Geomicrobiology, bulk sediment characteristics and pore water chemistry of sediment cores from Laguna Potrok Aike, southern Patagonia

Authors
Publisher
PANGAEA
Publication Date
Keywords
  • [Po4]3-
  • [So4]2-
  • % Dry Weight
  • <4 µM
  • 2000-63 µM
  • 63-4 µM
  • Adenosine 5-Triphosphate In Relative Light Units
  • Apatitic
  • Archaea Dgge No
  • Of Bands
  • Atomic
  • Atp
  • Background 25-30
  • Bacteria Dgge No
  • Of Bands
  • C/N
  • Ca2+
  • Calcium
  • Calcium
  • Standard Deviation
  • Carbon
  • Organic
  • Total
  • Carbon
  • Total
  • Carbon/Nitrogen Ratio
  • Ca Std Dev
  • Ch4
  • Chloride
  • Cl-
  • D13C Carb
  • D15N Bulk
  • Dapi
  • Delta 13C
  • Carbonate
  • Delta 15N
  • Bulk Sediment
  • Denaturing Gradient Gel Electrophoresis (Dgge)
  • Desoxyribonucleic Acid Per Volume
  • Dna
  • Fe2+
  • Fe Std Dev
  • Fluorescence Determination Of Dapi Stain
  • H
  • Hydrogen
  • Id
  • Iron
  • Standard Deviation
  • Iron 2+
  • K+
  • K Std Dev
  • Loi
  • Loss On Ignition
  • Low Accuracy
  • Magnesium
  • Magnesium
  • Standard Deviation
  • Methane
  • Mg2+
  • Mg Std Dev
  • Microorg Abund/Sed
  • Microorganisms
  • Abundance Per Unit Sediment Mass
  • Ms Mean In 10*Si
  • Multi-Sensor Core Logger
  • Msf-Point Sensor
  • Na+
  • Na Std Dev
  • Nitrate And Nitrite
  • Nitrogen
  • Total
  • No
  • No3+No2
  • Non-Apatitic
  • Number
  • P
  • Pasado
  • Phosphate
  • Phosphorus
  • Phosphorus
  • Inorganic
  • Phosphorus
  • Organic
  • Phosphorus
  • Standard Deviation
  • P Inorg
  • P Org
  • Potassium
  • Potassium
  • Standard Deviation
  • Potrok Aike Maar Lake Sediment Archive Drilling Project
  • P Std Dev
  • Sample Id
  • Si
  • Silicon
  • Silicon
  • Standard Deviation
  • Si Std Dev
  • Size Fraction < 0
  • 004 Mm
  • Clay
  • Size Fraction 0
  • 063-0
  • 004 Mm
  • Silt
  • Size Fraction 2
  • 000-0
  • 063 Mm
  • Sand
  • Sodium
  • Sodium
  • Standard Deviation
  • Sulphate
  • Sulphur
  • Total
  • Suscept
  • Susceptibility
  • Tc
  • Tn
  • Toc
  • Total
  • Ts
  • Vol%
  • Water Content Of Wet Mass
  • Water Wm
Disciplines
  • Biology
  • Ecology
  • Geography

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.

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