Determination of total destruction of organic matter in sediments of water bodies

A new scheme for determining the destruction of organic matter in bottom sediments with an account of methanogenesis and the dark assimilation of CO₂ is suggested. The values of the total destruction calculated according to the new methodical scheme increases by 30–60%.     

Processes of methane cycle and destruction of organic matter during the ice period in freshwater bodies of various types

Studies conducted in January to March at different parts of the Rybinsk Reservoir, in lakes of various types, and in a pond have demonstrated that the processes of СН₄ cycle during the ice period play an important role in the destruction of С_org and functioning of the ecosystem food webs. In highly trophic polluted lakes, the formation of СН₄ takes place both in silts and in the water column, and its gross production reaches a high summer level of 540–1220 mg С_org/(m² day). Taking into the account methanogenesis, 68–97% of the destruction of organic matter (OM) occurs due to the processes in bottom sediments. In the silts of productive lakes, only anaerobic processes cause the destruction.     

Bacterial Abundance and the Activity of Microbiological Processes in the Bay of Tugur of the Sea of Okhotsk

This paper presents the results of investigation of the total abundance and the biomass of bacterioplankton, the abundance of heterotrophic bacteria, and the activity of microbiological processes involved in the carbon cycle in the water of the Bay of Tugur of the Sea of Okhotsk. In different regions of the bay, the total abundance of bacterioplankton was found to vary from 0.51 × 10⁶ to 2.54 × 10⁶ cells/ml; the bacterioplankton biomass, from 8.5 to 46.5 g C/l; the abundance of heterotrophic bacteria, from 0.06 × 10³ to 2.12 × 10³ cells/ml; the bacterial assimilation of CO₂, glucose, acetate, and protein hydrolysate, from 0.8 to 6.3, from 0.11 to 1.88, from 0.07 to 0.56, and from 0.01 to 0.22 mg C/(m³ day), respectively; the degradation of organic matter ranged from 28 to 221 mg C/(m³ day); and the intensity of methane oxidation, from 0.0005 to 0.17 l CH₄/l. The spatial pattern and the functional characteristics of bacterioplankton in the Bay of Tugur were found to be dependent on the tidal dynamics.     

Dynamics of microbial oxidation of methane in the water of stratified lakes

Fluctuations of methane (CH₄) concentration and the dynamics of microbial methane oxidation (MO) were investigated in the water column of freshwater stratified lakes of different trophicity levels during various seasonal periods and throughout the diurnal cycle. Characteristics of vertical CH₄ distribution and ranges of methane transformation rates were determined and found to depend upon the lake productivity as well as seasonal and daily fluctuations of hydrological and hydrochemical parameters. The highest rate of MO was registered in highly eutrophic lakes during summer stagnation under conditions of formation of a distinct metalimnial water layer with MO up to 0.4–1.2 ml CH₄/(l day). Under the same conditions, a maximum amount of bacterioplankton (6–13 × 10⁶ cells/ml) was detected and CO₂ bacterial dark assimilation (DA) reached 50–72 μg C/(l day). In the metalimnion layer, a strong correlation (R = 0.74) was revealed between diurnal fluctuation dynamics of MO and DA.     

Intensity of the Microbiological Processes of the Methane Cycle in Different Types of Baltic Lakes

The intensity of the microbiological processes of methane formation (MF) and methane oxidation (MO) was determined in the sediments and water of different types of Baltic lakes. The emission of methane from the lake sediments and methane distribution in the water column of the lakes were studied as functions of the lake productivity and hydrologic conditions. During summers, the intensity of MF in the lake sediments and waters varied from 0.001 to 106 ml CH₄/(dm³ day) and from 0 to 3.2 ml CH₄/(l day), respectively, and the intensity of MO in the sediments and water varied from 0 to 11.2 ml CH₄/(dm³ day) and from 0 to 1.1 ml CH₄/(l day), respectively. The total methane production (MP) in the lakes varied from 15 to 5000 ml CH₄/(m² day). In anoxic waters, the MP comprised 9–18% of the total PM in the lakes. The consumption of organic carbon for methanogenesis varied from 0.03 to 9.7 g/(m² day). The role of the methane cycle in the degradation of organic matter in the lakes increased with their productivity.     

Methane cycle in different types of water bodies during the ice period

Studies conducted on different types of water bodies from January to March showed that microbial processes of the CH₄ cycle during the ice period are significant for degradation of organic carbon and trophic webs of the ecosystems. In productive polluted lakes, CH₄ formation occurs in sediments and in the water column, with its total output reaching the high summer level of 300–680 mL CH₄ /(m² day).     

Butyric acid bacteria of the genus <Emphasis Type="Italic">Clostridium</Emphasis> in the bottom sediments of inland basins of different types

The cell numbers and ecological characteristics of the distribution of certain species of butyric acid bacteria (BABs) of the genus Clostridium in the bottom sediments of inland basins of different types were studied using the optimal nutrient media. The seasonal dynamics of clostridial vegetative cells and spores in sediments with different ecological conditions were revealed. The cell numbers of the dominant BAB species were shown to depend on the redox potential of the sediments, the amount and composition of C_org, and the trophic state of the basin in general. C. pasteurianum was found to predominate in eutrophic lakes and reservoirs (5–11 × 10⁶ cells/cm³), C. butyricum and C. felsineum predominated in mesotrophic ones (2–11 × 10⁶ cells/cm³), and C. acetobutylicum was predominant in acidic chthonioeutrophic lakes and reservoirs (0.1–0.5 × 10⁶ cells/cm³). The lowest cell numbers of BABs were found in river sediments, whereas the highest numbers were recorded in the sediments of polysaprobic zones (0.1–1.0 × 10³ and 0.5–2.0 × 10⁷ cells/cm³ respectively).Translated from Mikrobiologiya, Vol. 74, No. 1, 2005, pp. 119–125.Original Russian Text Copyright © 2005 by Dzyuban.     

Bacterioplankton and Bacteriobenthos of Three Floodplain Lakes in the Lower Course of the Amur River

The main structural and functional characteristics of bacterioplankton and bacteriobenthos of three lakes in the lower course of the Amur River are presented: the total number of bacteria (TNB), biomass, the numbers of bacteria of certain aerobic and anaerobic groups; the intensities of methanogenesis (MG), methane oxidation (MO), assimilation of ¹⁴C-compounds, sulfate reduction (SR); and gross estimate of organic matter decomposition (D). Depending on the reservoir type and the anthropogenic load, TNB constituted (2.27 to 16.1) × 10⁶ cells/ml in water and (1.06 to 10.35) × 10⁹cells/cm³ in sediments; MO was 0 to 0.28 ml CH₄/(l day) in water and 0 to 8.4 ml CH₄/(dm³ day) in sediments; MG in sediments was 0.001 to 40 ml CH₄/(dm³ day); SR varied from 0.001 to 24.8 mg S/(dm³ day); D was 0.3 to 25 g C/(m² day) in water and 0.2 to 4.9 g C/(m² day) in sediments. The role of anaerobic microbial processes of organic matter decomposition was shown to increase with an increase in the anthropogenic load, attaining 95% of the total D in the ecosystem of an accumulating pond.