Microbial processes of the carbon and sulfur cycles in an ice-covered, iron-rich meromictic lake Svetloe (Arkhangelsk region, Russia)статья
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Дата последнего поиска статьи во внешних источниках: 24 мая 2017 г.
Аннотация:Biogeochemical, isotope geochemical and microbio-logical investigation of Lake Svetloe (White Seabasin), a meromictic freshwater was carried out inApril 2014, when ice thickness was ~0.5 m, and theice-covered water column contained oxygen to 23 mdepth. Below, the anoxic water column contained fer-rous iron (up to 240 llM), manganese (60 lM), sulfide(up to 2 lM) and dissolved methane (960 lM).The highest abundance of microbial cells revealed byepifluorescence microscopy was found in thechemocline (redox zone) at 23–24.5 m. Oxygenic pho-tosynthesis exhibited two peaks: the major one(0.43 lmol C L21day21) below the ice and the minorone in the chemocline zone, where cyanobacteriarelated to Synechococcus rubescens were detected.The maximum of anoxygenic photosynthesis(0.69 lmol C L21day21) at the oxic/anoxic interface,for which green sulfur bacteria Chlorobium phaeoclathratiforme were probably responsible, exceeded thevalue for oxygenic photosynthesis. Bacterial sulfate reduction peaked (1.5 lmol S L21day21) below thechemocline zone. The rates of methane oxidationwere as high as 1.8 lmol CH4L21day21at the oxi/anoxic interface and much lower in the oxic zone.Small phycoerythrin-containing Synechococcus-related cyanobacteria were probably involved inaccumulation of metal oxides in the redox zone.