Microbial processes of the carbon and sulfur cycles in an ice‐covered,iron‐rich meromictic lake Svetloe (Arkhangelsk region,Russia) |
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Authors: | Alexander S Savvichev Natalia M Kokryatskaya Svetlana A Zabelina Igor I Rusanov Elena E Zakharova Elena F Veslopolova Olga N Lunina Ekaterina O Patutina Boris K Bumazhkin Denis S Gruzdev Pavel A Sigalevich Nikolay V Pimenov Boris B Kuznetsov Vladimir M Gorlenko |
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Institution: | 1. Winogradsky Institute of Microbiology, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia;2. Institute of Ecological Problems of the North, Ural Branch, Russian Academy of Sciences, Arkhangelsk, Russia;3. Institute of Bioengineering, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia |
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Abstract: | Biogeochemical, isotope geochemical and microbiological investigation of Lake Svetloe (White Sea basin), a meromictic freshwater was carried out in April 2014, when ice thickness was ~0.5 m, and the ice‐covered water column contained oxygen to 23 m depth. Below, the anoxic water column contained ferrous iron (up to 240 μμM), manganese (60 μM), sulfide (up to 2 μM) and dissolved methane (960 μM). The highest abundance of microbial cells revealed by epifluorescence microscopy was found in the chemocline (redox zone) at 23–24.5 m. Oxygenic photosynthesis exhibited two peaks: the major one (0.43 μmol C L?1 day?1) below the ice and the minor one in the chemocline zone, where cyanobacteria related to Synechococcus rubescens were detected. The maximum of anoxygenic photosynthesis (0.69 μmol C L?1 day?1) at the oxic/anoxic interface, for which green sulfur bacteria Chlorobium phaeoclathratiforme were probably responsible, exceeded the value for oxygenic photosynthesis. Bacterial sulfate reduction peaked (1.5 μmol S L?1 day?1) below the chemocline zone. The rates of methane oxidation were as high as 1.8 μmol CH4 L?1 day?1 at the oxi/anoxic interface and much lower in the oxic zone. Small phycoerythrin‐containing Synechococcus‐related cyanobacteria were probably involved in accumulation of metal oxides in the redox zone. |
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