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259,896,000 Yen (FY2001; 20,148,000Yen)
The West Siberian Wetland is one of the main sources of atmospheric methane; however, the amount of methane emission and the ecological factors controlling those emissions remain unknown. An automatic sampling and analysis system for measuring methane and CO2 fluxes from wetland soils was developed and applied to the methane flux measurements at two wetland sites in the southern part of West Siberia. Measurements were performed two distinct types of open wetlands typical for the area' mesotrophic open bog and patterned wetland with forested ridges, flarks and water pools. The methane analysis was performed using novel semiconductor sensor. Seasonally averaged methane flux rate was determined to be 12.7 mg/m2/h at the open bog and 2.1 mg/m2/h at the patterned wetland. The temporal variations of flux correlates with soil temperature in short term (3 days averages), but in the long term the decay of the flux in autumn delays for up to a month behind the decline in soil temperature.
We studied the relationship between physicochemical soil properties (temperature, pH, Eh, the content of mineral and organic compounds) and methanogenic activity. The acidic environment was found to be characterized by high rates of methane production at the depth of 15-25 cm below water table level. The most significant environmental factor affecting methane production was redox-potential. Furthermore, we studied on the cellulolytic mic roorganisms in the wetland. They should be very important in the breakdown of plant residues and carry out the first step in organic matter degradation, which eventually results in the production of methane. However, improving our understanding of cellulolytic hydrolysis is impeded by a lack of basic knowledge of the process. We investigated the vertical distribution of cellulolytic hydrolysis activity, and isolated and characterized cellulose-degrading microorganisms. Oxic cellulase activity was found in the surface layer at all sites surveyed. Anoxic activity was detected only in the deep layer in an Equisetum bog. This result suggests an interaction between cellulose-degrading microorganisms and vegetation. In an incubation study of peat samples with cellulose treated with phosphoric acid, the cellulose was degraded best at 30 °C, pH 7, and relatively high ionic strength , though these conditions were not representative of the site properties.
Siberia, wetland, methane, methanogen, cellulose