V. N. Lukashin

Comprehensive studies of the Caspian Sea system during cruise 35 of the R/V Rift

141 A interdisciplinary expedition was conducted aboard the R/V Rift (cruise 35; June 4–19, 2010) to study the system of the Caspian Sea. The hydrophysi cal, hydrochemical, sedimentological, and geological characteristics of the atmosphere, the water’s thick ness, and the bottom sediments were investigated. The works were performed in the Middle Caspian Sea and lengthwise the submeridional transect up to the South Basin of the Caspian Sea (Fig. 1).

An integrated study in the northern Caspian Sea: The 30th voyage of the R/V Rift

439 The 30th voyage of the R/V Rift was conducted on April 17–28, 2009. The main goal of the expedition was the comprehensive integrated exploration of the contemporary sedimentation system in the northern Caspian Sea in the mid spring season. The basic tasks involved measurements of the marine environmental features and the collection of relevant samples for the subsequent analysis and interpretation of the obtained data. Use was made of various techniques: CTD and ADCP profiling; the recording of currents with moor ing stations; optical observations with a Secci disk, a PUM transparency probe, a floating spectroradiome ter, and satellite data reception; hydrochemical deter minations of the О2, Si, and PO4; sedimentology (the aerosols, suspended matter, and pigments and the use of a Coulter counter); and marine biology (collecting samples of phyto and zooplankton). One of the main goals of the expedition was the lifting and mooring of subsurface buoy stations with sediment traps and “Potok” current meters. The route of the expedition and the stations’ positions are shown in Fig. 1.

The MSL-110 small sediment trap

A simple construction of the MSL-110 sediment trap developed at the Laboratory of Physical-Geological Research of the Shirshov Institute of Oceanology, Russian Academy of Sciences, is presented. The trap is easily assembled from standard parts available at stores. The trap is easy to use, reliable, and inexpensive. It is applied for determination of sedimentary matter fluxes and their components in water columns of seas, lakes, and other water reservoirs.

On vertical particle fluxes in the Caspian Sea

The first results of studies of vertical fluxes of sediment particles using the sediment traps at the Trans-Caspian section are presented. The flux values and distribution regularities are established. The fluxes of particles forming the sediment are also determined. The intra-annual variability in the fluxes corresponds to the seasonal variability of the biological activity. Above the northern slope of the Derbent Basin, the maximum vertical fluxes are recorded in the winter, which is caused by the intensification of the near-bottom currents.

Chemical composition of aerosols in the near-water surface atmospheric layer of the central Caspian Sea in the winter and autumn of 2005

The chemical composition (43 elements) of aerosols is reviewed for the Caspian Sea based on nine samples taken in the winter and autumn of 2005. The aerosols are considered as geological material incoming to the sea from the atmosphere. The major aerosol components are distinguished and the degree of the concentration is calculated for a series of trace elements relative to their contents in the lithosphere. Se, Cd, Sb, Au, and Pb are concentrated by one-two orders of magnitude, which is related to the pollution. A correlation matrix is given for the studied elements, and their relations with the major components of the aerosols are revealed.

The geochemistry of deepwater particulate matter over the hydrothermal field at 9°d50′ N (the East Pacific Rise)

The results of geochemical studies of particulate matter in the water mass over the hydrothermal field at 9°50′ N on the East Pacific Rise are presented. The particulate matter was tested in background waters, in the buoyant plume, and in the near-bottom waters. The contents of Si, Al, P, Corg, Fe, Mn, Cu, Zn, Ni, Co, As, Cr, Cd, Pb, Ag, and Hg were determined. No definite correlations were found between the ele-ments in the background waters. Many of the chemical elements correlated with Fe and associated with its oxyhydroxides in the buoyant plume. In the near-bottom waters, microelements are associated with Fe, Zn, and Cu (probably, to their sulfides formed under fluid mixing with seawater). The matter precipitated in a sed-imentation trap was similar to the near-bottom particulate matter in the elemental composition.

Sedimentary matter fluxes in the contour current sedimentation system over the continental slope of the Norwegian Sea

The sedimentation system of the bottom contour current over the continental slope of Bear Island in the Norwegian Sea is considered. The nepheloid layer that provides the high horizontal flux of sedimentary material represents the main source of matter for the bottom sediments. The vertical particulate matter flux is largely formed in the nepheloid layer; the flux from higher layers of the water column is insignificant. Horizontal and vertical fluxes of sedimentary matter show a positive correlation. The flux of the matter from the bottom sediment into the nepheloid matter and the residence time of particles in the latter are estimated.

Aerosols in the Near-Water Surface Layer of the Caspian Sea

The first data on the concentrations, fluxes, and mineral and chemical compositions of aerosols from the near-water surface layer of the Caspian Sea are presented. It is shown that the aerosol fluxes onto the sea surface are comparable to the fluxes of a lithogenic substance in a water column. The mineral and chemical compositions of aerosols depend on the carrying air masses that pass through different regions. The coefficients of enrichment of aerosols with chemical elements relative to the upper lithosphere and their correlation relationships are studied.

Geochemistry of dispersed sedimentary matter and its fluxes in the water column of the Caspian Sea

The first data on the chemical composition of dispersed matter from sedimentary traps are reported. The suspended components of sedimentary matter (amorphous silica, organic matter, carbonates, and lithogenic material, as well as Fe, Mn, and minor elements) are considered. As a result, it is shown that the intraannual variability in vertical fluxes of sedimentary matter is characterized by a seasonal increase in spring and autumn. The high fluxes of the components of sedimentary matter on the northern and southern slopes of the Derbent Basin in winter are explained by precipitation of material from the nepheloid layer that forms over the contour current.

Mineral composition of sedimentary matter in the Caspian Sea

Data on the mineral composition of sedimentary matter and its fluxes in the sediment system of the Caspian Sea are presented. River runoff, aerosols, particulate matter from sediment traps, and the upper layer (0–1 cm) of bottom sediments are considered. The contents of detrital minerals (quartz, albite, and K-feldspar), clay minerals (illite, chlorite, and kaolinite), and carbonates (calcite, Mg-calcite, dolomite, aragonite, and rhodochrosite) are determined. Gypsum was found in bottom sediments but is absent in the other object of the sediment system.