Chemical composition of bottom sediments from the northern part of the Deryugin Trough, Sea of Okhotsk

Distribution trace element contents in the upper (up to 5 m) Holocene-Upper Pleistocene sediment layer along the northern and southern sublatitudinal profiles in the northern part of the Deryugin Trough is discussed. Mathematical processing of chemical analysis data has been made. On the basis of the cluster analysis 16 elements have been combined into 5 geochemical groups. Two of them (1 - Ag-Mo group and 2 - Mn-Ba-Ni-Sr group) were considered in detail. Analysis of Ag and Mo distributions in the sediments and findings of molybdenite permitted to conclude that enrichment of the sediments by these elements resulted from edaphic washing of magmatic rocks containing Ag-Mo mineralization and probably located on the northwestern slope of the Deryugin trough. The second geochemical group is most likely connected with hydrothermal barite mineralization found in the northeastern part of the Deryugin trough. Considering Mn distribution in bottom sediment cores supply of Mn was pulsating. This allows concluding that during Holocene - Late Pleistocene three cycles of hydrothermal activity occurred in the Deryugin Trough, and the most intensive one was in Holocene.

Chemical composition of ferromanganese manifestations from the Sea of Okhotsk

New data on microstructures and mineral and chemical compositions of ferromanganese crusts sampled from the western slope of the Kuril Island Arc in the Sea of Okhotsk during cruises of R/V Vulkanolog are discussed. The study of the crusts using analytical electron microscopy methods revealed that their manganese phase is represented by vernadite, Fe-vernadite, todorokite, asbolane, and asbolane-buserite, while iron phase consists of hematite, hydrohematite, ferroxyhite, and magnetite. Lithic mineral assemblage includes apatite, quartz, epidote, and montmorillonite. According to chemical analysis most of the crusts contain significant part of volcanogenic and hydrothermal material. It is evident from elevated values of Mn/Fe and (Mn+Fe)/Ti ratios, low concentrations of some trace elements, and positive Eu anomaly.

Feeding parameters of copepods from upwelling areas

Feeding patterns of mass herbivorous copepods in upwelling areas are investigated. Daily rations and aspects of their formation are examined in Calanoides carinatus (Benguela upwelling), Calanus pacificus (off the California coast), and Calanus australis (Peru upwelling). Rations were calculated based on gut plant pigment contents obtained at daily stations using laser spectrofluorometry, experimental data on the rate of gut evacuation and data on the carbon/chlorophyll ratio in phytoplankton and particulate matter at the respective stations. When phytoplankton was abundant, diel feeding rhythms were not pronounced and gut pigment level was high during the entire 24-h period. When phytoplankton biomass was low, distinct feeding rhythms were pronounced with a nocturnal maximum. During active upwelling intensive feeding on phytoplankton supports energy (respiration) and plastic (growth, development, reproduction, accumulation of reserves) metabolism of copepods. When upwelling was inactive, the surface part of the population feeds less actively and is able only partially to cover its energy expenditures. The actively growing and reproducing populations of C. pacificus and C. carinatus may consume close to 20% of primary production, whereas the inactive population of C. australis consumed only 0.2% of primary production when upwelling weakened.

Geochemistry of picrite basalts from the Liohi Volcano

Research of the ocean floor using the Mir submersibles carried out south of the Hawaiian Archipelago allowed to recover flows of recent picrite basalts. Lava vents are confined to a field of development of open fractures of a gjar type. Basalts represent initial lava flows in the structure of the Hawaiian volcanic archipelago. Considering contents of alkali and rare-earth elements in them, the picrite basalts of the bottom could be assigned to a series of island tholeiites. They are products of high level melting of asthenospheric matter at depth about 75-80 km as a result of decompression near a deep fracture that occurred in the lithosphere and asthenosphere. Similar picrite basalts were found in the base of the youngest volcano of the Hawaiian chain the Loihi Volcano. With respect to contents of alkali metals, these rocks are assigned to the subalkaline series of rocks formed during melting of garnet lherzolites. This could probably be explained by supply of melts from deeper levels of the asthenosphere after partial packing of an initial magma effluent fracture.

Composition of organic matter from samples of massive sulfides, bottom sediments, and seawater collected within the Logachev and Broken Spur hydrothermal fields, Mid-Atlantic Ridge

Lipid components of hydrothermal deposits from the unusual field at 14°45'N MAR and from the typical field at 29°N MAR were studied. For the first time mixed nature of organic matter (OM) from hydrothermal sulfide deposits was established with use of biochemical, gas chromatographic, and molecular methods of studies. In composition of OM lipids of phytoplankton, those of chemosynthesis bacteria and non-biogenic synthesis lipids were determined. Specific conditions of localization of sulfide deposits originated from ''black smokers'' (reducing conditions, absence of free oxygen, presence of reduced sulfur preventing OM from decomposition) let biogenic material, including bacterial one, be preserved in sulfide deposits. The hydrothermal system at 14°45'N MAR is characterized by geological, geochemical and thermodynamic conditions allowing abiogenic synthesis of methane and petroleum hydrocarbons. For sulfide deposits at 29°N and other active hydrothermal fields known at MAR, abiogenic synthesis of hydrocarbons occurs in lower scales.

Grain size composition of marine and river bottom sediments

According to average grain size parameters (Kd, Kd1) recent sediments from the northern Caspian Sea and the Barents Sea shelf are similar, while sediments from the Norwegian Sea are closer to their counterparts of the World Ocean. Seaward content of subcolloidal (<0.001 mm) size fraction increases against the background of decreasing proportions of coarse- and medium-grained pelite (<0.01 mm) material.

Hydrocarbons in surface layer bottom sediments from the North Dvina Riverand the southern part of the Dvina Bay, White Sea

Analysis of molecular composition of alkanes in bottom sediments of the southern part of Dvina Bay (White Sea) in October 2001 revealed the following main peculiarities of hydrocarbon behavior in the estuary: dominating of high molecular C23-C45 compounds and irregular distribution of hydrocarbons in bottom sediments as a result of high sedimentation rate and active hydrodynamics in the studied area.