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We have investigated the distribution of photosynthetic pigments (chlorophyll and carotenoids), total organic carbon (TOC), and biogenic silica in the surface sediments throughout Lake Baikal and suggested factors controlling this distribution.
The concentrations of photosynthetic pigments preserved in the surface sediments of Lake Baikal have been established to be high in the Southern basin and minimum in the Central basin, including the Akademichesky Ridge, while TOC is distributed rather evenly, and the contents of biogenic silica are higher in the Central and Northern basins. The oxidizing conditions in the surface sediments and the low sedimentation rate in the Akademichesky Ridge caused intense decomposition of pigments. The large inflow of the Selenga River significantly disturbs sedimentation in the Southern basin and thus causes uneven spatial distribution of pigments. Carotenoids found in the Southern basin are also diverse, thus suggesting their origin from different classes of algae.

Microorganisms of the Baikal Rift are of peculiar interest owing to their isolated evolution and the ancient origin of Lake Baikal. Samples of rocks sedimented at various stages of the Baikal Rift development have been obtained by drilling. Based on microbiological examination of bottom samples from the Baikal basin, a collection of more than 2200 microbial isolates was made. They include the genera Micrococcus, Staphylococcus, Bacillus, and Nocardia; numerous nonsporogenous cocci and bacilli with well-pronounced capsules; fast-moving Gram-negative rods, assigned to pseudomonads; sessile Gram-negative cells, actinomycetes, and yeast. The eukaryotes of the ground samples also contain mold fungi.
The morphological features were studied by light microscopy of colored microbial cells and using scanning and transmission microscopes.

Microorganisms isolated from sediments of Lake Baikal and nearby thermal springs (Zmeinyi and Goryachenskii) have been tested as producers of restriction enzymes. The production has been detected in 20% of the investigated strains. Three strains are of particular practical interest. Two of them are thermophilic producers of novel enzymes, and the restriction endonuclease from the third one demonstrates an unusual sensitivity to dam methylation of the recognition site.
It has been shown that the content of viable microorganisms varied throughout the sediments.

We present new data on the distribution and composition of n-alkanes (biomarkers) and humic acids in the Holocene and Pleistocene bottom sediments of Northern Baikal accumulated under different sedimentation and paleoclimatic conditions. These data show significant amounts of allochthonous organic matter (OM) in the Holocene sediments of various sedimentation settings, which was supplied mainly with suspension flows. During glaciations, accumulation of both allochthonous and autochthonous OM was considerably reduced. In these periods, when no diatoms existed, autochthonous OM was produced from cyanobacteria and blue-green algae.

Results of study of winter eolian transport in the region of the Akademichesky Ridge of Lake Baikal are presented, based on data of granulometric and mineralogical analyses of the suspended matter of snow cover accumulated for the period January-March 1998. The wind velocities necessary for transportation of quartz grains of different sizes from the Baikal Ridge (western shore of Baikal) to the study region are calculated. The conclusion is drawn that winter eolian transport plays an important role in the supply of clastogene material to the region of the Akademichesky Ridge.

Results of geochemical study of suspended matter (SM) from the snow cover of the Akademichesky Ridge of Lake Baikal are presented. Geochemical data are processed by methods of the mathematical theory of pattern recognition on the basis of distance functions. The conclusion is drawn that the eolian material of the Akademichesky Ridge was transported mainly from the western shore of Lake Baikal. Solution of the optimization problem has shown that 45% of the studied SM was transported from the western shore, 15% from the eastern one, and 40% from far regions.

Neutron-activation analysis with the use of the X-ray fluorescence method permitted us to determine a number of rock-forming and trace elements in the samples of atmospheric aerosol collected on air filters and in snow samples taken in the period 1980-97. Based on their REE patterns, we have estimated the role of global and regional supply of finely dispersed detritus in the sedimentation in Lake Baikal. A comparative analysis of the elemental composition of suspensions of the main rivers feeding the lake was performed. The earlier and newly determined contents of REE, Fe, Hf, Th, and Rb in the samples are compared with the clarkes of these elements in continental clays.

Thermal conductivity of rocks is a key parameter in heat flow determination. Thermal conductivity of the Baikal bottom sediments in cores from first underwater boreholes (BDP-93 and BDP-96) was measured by a needle probe and a thermal-conductivity comparator, and the two methods showed a difference of up to 30-50% in the values of both thermal conductivity and heat flow. In this study we used a new method implying evaluation of thermal conductivity of sediments through interpretation (inversion modeling) of temperature field recovery in boreholes after the cessation of drilling. The modeling parameters are steady-state temperature and thermal conductivity of bottom sediments at a depth of temperature monitoring. As a result, it was concluded that the needle probe measurements are reliable, and the thermal-conductivity comparator cannot be used to study unconsolidated sediments with water contents above 40%. The obtained estimates of steady-state temperature and geothermal gradient confirmed that the heat flow is relatively low (about 50 mW/m²) in the Bugul'deika saddle (BDP-93) and high (78 mW/m², an updated value) in the axial part of the Akademichesky Ridge (BDP-96). The new method allowed us to estimate, for the first time, the thermal-diffusivity coefficient and the specific heat capacity of the Baikal sediments. Thus, the numerical analysis of temperature monitoring data permits estimation of all geothermal parameters of sediments.

Structural studies of BDP-98 core recovered during deep drilling on the Akademichesky Ridge (Baikal Drilling Project) have shown that the Baikal bottom sediments are cut by tension and shear joints of various scales, locally clustered into zones of fracturing. Specific features of the fractures, formed under the conditions of rifting and diagenesis, are related to their latent character, effects of fluid pressure, prevalently normal geometry of extensional jointing, and the structure of the fracturing zones which favors horizontal extension. The obtained results reveal the regularities of active extensional fracturing, as the latter in the case of Baikal is not overprinted with earlier deformation.

Thermodynamic indices of biogenic silica have been calculated on the basis of data of X-ray spectral electron probing and the chemical composition of diatom valves. Application of these new data to a physicochemical model for Lake Baikal allowed us to put forward a new concept of biogenic-silica dissolution, which explains the constant concentration of silicium in the Baikal water. The data also suggest that the conservation of biogenic silica in bottom sediments depends on the amorphous state of SiO² making up the valve. Preliminary data on the involvement of biogenic opal in diagenesis of the bottom sediments are reported.