Biogeochemistry (speciation and isotopes of S and C) in bottom sediments, water and bacterial mats from the White Sea

This publication presents results of microbiological and biogeochemical studies in the White Sea. Material was obtained during a series of expeditions in 1999-2002. The studies were carried out in the open part of the White Sea, in the Onega, Dvina and Kandalaksha Bays, as well as in the intertidal zone of the Kandalaksha Bay. Quantitative characteristics of activity of microbial processes in waters and bottom sediments of the White Sea were obtained. The total number of bacteria was equal to 150000-800000 cells/ml, and intensity of dark CO2 assimilation was equal to 0.9-17 µg C/l/day. Bacterial sulfate reduction was equal to 3-150 mg S/m**2/day, and methane formation and oxidation was equal to 13-6840 and 20-14650 µl CH4/m**2/day, respectively. Extremely high values of intensity of all principal microbial processes were found in intertidal sediments rich in organic matter: under decomposing macrophytes, in local pits at the lower intertidal boundary, and in the mouth of a freshwater brook. Average hydrogen sulfide production in highly productive intertidal sediments was 1950-4300 mg S/m**2/day, methane production was 0.5-8.7 ml CH4/m**2/day, and intensity of methane oxidation was up to 17.5 ml CH4/m**2/day. Calculations performed with account for areas occupied by microlandscapes of increased productivity showed that diurnal production of H2S and CH4 per 1 km**2 of the intertidal zone (August) was estimated as 60.8-202 kg S/km**2/day and 192-300 l CH4/km**2/day, respectively

Metagenomic data of the microbial community of the chemocline layer of the meromictic subarctic Lake Bolshie Hruslomeny, North European Russia

The Lake Bolshie Hruslomeny is located on the shores of the Kandalaksha Bay of the White Sea, North European Russia. This lake, formed from the sea bay and still retaining the subsurface connection with the sea, is meromictic, with a fresh oxygenated upper layer and an anoxic brackish hypolimnion with high concentrations of methane and hydrogen sulphide. To characterize the microbial communities involved in the carbon and sulfur cycles in the lake, we sequenced the metagenome of a water sample collected at the chemocline level. At the phylum level, Chlorobi, Proteobacteria, Bacteroidetes and Firmicutes were the most numerous groups. The obtained data will help investigate the diversity and ecological role of the microbial community in the Lake Bolshie Hruslomeny and provide insight into the biogeochemical processes in subarctic lakes. The raw sequencing data is available from the NCBI Sequence Read Archive (SRA) database under the BioProject PRJNA503531