Geochemical and microbiological characteristics of sediments near the Malenky mud volcano (Lake Baikal, Russia), with evidence of Archaea intermediate between the marine anaerobic methanotrophs ANME-2 and ANME-3

Detailed lithological, biogeochemical and molecular biological analyses of core sediments collected in 2002–2006 from the vicinity of the Malenky mud volcano, Lake Baikal, reveal considerable spatial variations in pore water chemical composition, with total concentrations of dissolved salts varying from 0.1 to 1.8‰. Values of methane δ¹³С in the sediments suggest a biogenic origin (δ¹³С_min. ?61.3‰, δ¹³С_max. ?72.9‰). Rates of sulphate reduction varied from 0.001 to 0.7 nmol cm^?3 day^?1, of autotrophic methanogenesis from 0.01 to 2.98 nmol CH₄ cm^?3 day^?1, and of anaerobic oxidation of methane from 0 to 12.3 nmol cm^?3 day^?1. These results indicate that methanogenic processes dominate in gas hydrate-bearing sediments of Lake Baikal. Based on clone libraries of 16S rRNA genes amplified with Bacteria- and Archaea-specific primers, investigation of microbial diversity in gas hydrate-bearing sediments revealed bacterial 16S rRNA clones classified as Deltaproteobacteria, Gammaproteobacteria, Chloroflexi and OP11. Archaeal clone sequences are related to the Crenarchaeota and Euryarchaeota. Baikal sequences of Archaea form a distinct cluster occupying an intermediate position between the marine groups ANME-2 and ANME-3 of anaerobic methanotrophs.     

Bacterial communities in Hoito Gol hot spring,Eastern Sayan,and the ecologic-geological conditions of their development

Hoito Gol hot spring of weakly mineralized warm (36–29°C) neutral and partly alkaline nitrogen-carbon dioxide waters belongs to the hydrogeological structure of the actively water-flooded fault marked by the Sentsy River at the southwestern termination of the Baikal rift system. The spatiotemporal evolution of the major parameters of the underground aqueous ecosystem of this spring is controlled mainly by geological and geodynamic factors, whereas the parameters of the surface system are determined mostly by bacterial factors. Variations in these factors are correlated with changes in the composition, structure, and spatial distribution of the bacterial communities.     

Chemical and biological features of the saline Lake Krasnovishnevoye (Baraba,Russia) in comparison with Lake Malinovoe (Kulunda,Russia): a reconnaissance study

The Baraba and Kulunda steppes are located in southwestern Siberia in an area with an arid continental climate. This paper presents results of the first study of the hypersaline Lake Krasnovishnevoye(Baraba steppe, TDS(total dissolved solids)=297 g/L, pH 7.88). The major chemical, mineralogical and biological features of the lake were studied and compared to those of Lake Malinovoe, a typical saline neutral lake of Kulunda steppe(TDS=396 g/L, pH 7.63). The phytoplankton composition and the culturable diversity of anoxygenic phototrophic bacteria from Lake Krasnovishnevoye correspond to the ones in the Kulunda lakes. Nevertheless, the peculiarities of water composition and regime of Lake Krasnovishnevoye reduce the biodiversity to prokaryotes and unicellular algae.     

Taxonomic and Ecological Characterization of Cyanobacteria from Some Brackish and Saline Lakes of Southern Transbaikal Region

正Brackish and saline lakes are common in the arid zones of the Earth.They are unique ecosystems with extremely high p H values and high mineralization levels(up to saturating concentrations).These lakes are inhabited by     

Hydrochemical and microbiological characteristics of bog ecosystems on the isthmus of Svyatoi Nos Peninsula (Lake Baikal)

Presented are the results from hydrochemical and microbiological investigations into Arangatui bog ecosystems on the isthmus of Svyatoi Nos Peninsula on the shores of Lake Baikal. The formation features of bog waters as a result of a rise in the lake’s water level.     

Hydrochemical and microbiological characteristics of the Gusino-Ubukunskaya group of water bodies

Results of hydrochemical and microbiological studies of five largest water bodies belonging to the Gusino-Ubukunskaya group are presented. Present-day environmental state of the ecosystem subject to anthropogenic load is described. The possibility of using water quality parameters of the investigated lakes as indicators of the degree of contamination of waters flowing into the Baikal Lake is shown.Translated from Vodnye Resursy, Vol. 32, No. 1, 2005, pp. 79–84.Original Russian Text Copyright © 2005 by Khakhinov, Namsaraev, Ulzetueva, Barkhutova, Abidueva, Banzaraktsaeva.     

Microbial processes and factors controlling their activities in alkaline lakes of the Mongolian plateau

A striking feature of the Mongolian plateau is the wide range of air temperatures during a year,-30 to 30°C.High summer temperatures,atmospheric weathering and the arid climate lead to formation of numerous alkaline soda lakes that are covered by ice during 6–7 months per year.During the study period,the lakes had p H values between 8.1 to 10.4 and salinity between 1.8 and 360 g/L.According to chemical composition,the lakes belong to sodium carbonate,sodium chloride-carbonate and sodium sulfate-carbonate types.This paper presents the data on the water chemical composition,results of the determination of the rates of microbial processes in microbial mats and sediments in the lakes studied,and the results of a Principal Component Analysis of environmental variables and microbial activity data.Temperature was the most important factor that influenced both chemical composition and microbial activity.p H and salinity are also important factors for the microbial processes.Dark CO 2 fixation is impacted mostly by salinity and the chemical composition of the lake water.Total photosynthesis and sulfate-reduction are impacted mostly by p H.Photosynthesis is the dominant process of primary production,but the highest rate(386 mg C/(L?d)) determined in the lakes studied were 2–3 times lower than in microbial mats of lakes located in tropical zones.This can be explained by the relatively short warm period that lasts only 3–4 months per year.The highest measured rate of dark CO 2 assimilation(59.8 mg C/(L?d)) was much lower than photosynthesis.The highest rate of sulfate reduction was 60 mg S/(L?d),while that of methanogenesis was 75.6 μLСН 4 /(L?d) in the alkaline lakes of Mongolian plateau.The rate of organic matter consumption during sulfate reduction was 3–4 orders of magnitude higher than that associated with methanogenesis.     

Water regime and variations in hydrochemical characteristics of the soda Salt Lake Khilganta (Southeastern Transbaikalia)

Hydrochemical and biogeochemical processes in Lake Khilganta were studied during more than ten years. The lake was shown to pass through periods of wetting and drying. This is accompanied by considerable changes in water chemistry and microbiological processes. During the passage from a wet to a dry period, lake water mineralization increases from 40 to 260 g/l and pH decreases from 9.9 to 7.1. At the same time, the isotope composition of organic matter carbon in bottom deposits becomes lighter (from −15.6 to −30.6‰), as well as that of carbon in carbonates (from +4.1 to −8.6‰), due to the lower rate of photosynthetic processes in lake bacterial mats. The order of salt precipitation during the passage from a wet to a dry period and the mechanism of maintaining water pH are considered. A possible similarity between the modern processes in Lake Khilganta and the processes in analogous Pre-Cambrian water bodies is discussed, and the hypothesis regarding the possibility of wider development of soda water bodies at early stages of Earth’s history is considered.