A. N. Novigatsky

Genesis and spatial distribution of suspended particulate matter concentrations in the Kara Sea during maximum reduction of the Arctic ice sheet

The suspended particulate matter (SPM) distribution in the water column of the Kara Sea including the Ob and Yenisei river estuaries was investigated in September 2007 and 2011, i.e., during periods of the maximum reduction of drift ice in the Arctic Ocean. The increased SPM concentrations in the surface layer of the Ob Estuary (26 and 16 mg/L on average in the fresh and saline (3–10 psu) water, respectively) were revealed in 2007 as compared with its values available from previous publications. The SPM concentrations and share of the terrigenous component in the latter in the Ob Estuary (2007) was =10 times higher than in the estuary of the Yenisei River (2011). The SPM concentration decreased exponentially in response to fresh and saline water mixing in the marginal filter (MF) areas of these rivers. The main transformation of the SPM composition at the transition from estuary to shelf waters took place within the salinity frontal zone (coagulation and sorption stage of the MF). The impact of terrigenous material on marine SPM composition in 2011 decreased in the northerly direction. The anomalous desalination of the sea surface layer in 2007 resulted in significant lightening of the organic carbon isotopic composition in the western part of the Kara Sea. This means that the impact of terrigenous material on SPM composition insignificantly decreased in the northerly direction. It was shown that mineral matter was distributed from the northeastern extremity of the Novaya Zemlya Archipelago in the northeasterly direction. At the same time, mineral particles transported by rivers from West and East Siberia prevail in the terrigenous SPM constituent in the Kara Sea up to 76°30′ N. Our data indicated that the processes of cross-shelf SPM transport in the Kara Sea were controlled by bottom topography.

Specific features of the distribution of trace and rare earth elements in recent bottom sediments in the lower course of the Severnaya Dvina River and White Sea

The paper discusses results of the lithogeochemical examination of recent bottom sediments in the lower course of the Severnaya Dvina River and White Sea. It has been established that the average concentration of several trace elements (Hf, Sc, Co, Y, Ni, V, Cr, Zr, Ba, and others) therein correlates with the content of the silt-pelite fraction. Maximal concentrations of the majority of above elements are confined to the silty-clayey sediments at the Basin/Dvina Bay boundary. They localized near the coastal zone only for some clastophile (Zr, Cr, and others). Typical values of the hydrolyzate module, chemical index of alteration, and Al2O3/SiO2 ratio in the aleuropelitic and pelitic sediments of the Severnaya Dvina River delta, Dvina Bay, and the Dvina Bay Basin boundary suggest that these sediments are confined to sufficiently cold climate settings. Data points of sediment composition in discriminant paleotectonic diagrams are scattered over a large field probably due to high contents of the weakly weathered plagioclases, micas, and amphiboles, as well as the hydrogenic process promoting the accumulation of Fe and Mn. The PAAS-normalized spectra of rare earth elements (REE) in bottom sediments of the Pinega and Severnaya Dvina rivers, marginal filter of the latter river, Dvina Bay, and the Dvina Bay Basin boundary are similar to the REE distribution in clayey rocks of the ancient platform cover (except for a slight positive Eu anomaly). The REE systematics and distribution pattern of compositional data points of recent bottom sediments in the GdN/YbN-Eu/Eu* and Eu/Eu*-Cr/Th diagrams and values of several indicator ratios of trace elements suggest that the studied rocks were formed by the mixing of clastic materials from geochemically contrast provenances: northwestern provenance (Kola-Karelia geoblock), which is mostly composed of the Archean and Early Proterozoic crystalline complexes, and the southeastern provenance (northwestern periphery of the Mezen syncline), which is almost totally composed of Phanerozoic sedimentary rocks. The latter provenance likely played a crucial role in the geochemical signature of recent bottom sediments over a significant area of the White Sea.

Vertical flux of phytoplankton and particulate matter in the White Sea according to the long-term exposure of sediment traps

The vertical fluxes of phytoplankton (VFPhyto) and particulate organic carbon (VFPOC) in the White Sea were determined using seven long-term (292 to 296 days) sediment traps moored at five stations at 67–255 m depths. The annual VFPhyto and VFPOC ranged from 0.55 to 24.64 g C/m2 and from 3.7 to 93.9 g C/m2, respectively. The highest VFPhyto was observed in the Basin region located close to the Gorlo along the Tersk coast. The algal biomass accounted for 15–43% of the VFPOC. Diatoms comprised the most important group, accounting for 83–100% in the sedimented biomass. Thalassiosira nordenskioeldii dominated in the VFPhyto at all the stations except for the station in the basin close to Onega Bay, where Ditylum brightwellii was the most abundant.

Distribution and composition of suspended particulate matter in the Atlantic Ocean: Direct measurements and satellite data

The main purpose of this work is to study the real distribution and spatial–temporal variations of suspended particulate matter and its main components in surface waters of the Atlantic Ocean on the basis of direct and satellite measurements for development of new and perfection of available algorithms for converting satellite data. The distribution fields of suspended particulate matter were calculated and plotted for the entire Atlantic Ocean. It is established that its distribution in the open ocean is subordinate to the latitudinal climatic zonality. The areas with maximum concentrations form latitudinal belts corresponding to high-productivity eutrophic and mesotrophic waters of the northern and southern temperate humid belts and with the equatorial humid zone. Phytoplankton, the productivity of which depends primarily on the climatic zonality, is the main producer of suspended particulate matter in the surface water layer.

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.

Determination of the concentration of mineral particles and suspended organic substance based on their spectral absorption

A method to determine the concentrations of the particulate mineral matter (CPMM) and the particulate organic matter (CPOM) is suggested. The values of CPMM and CPOM are calculated from the measurements of the spectral coefficients of the light absorption aPOM(440) and aPMM(750) using empirical equations. The latter have been obtained by comparing the concentrations of the suspended solids measured by means of the gravimetric method with the spectral values of the optical density of the suspended matter settled on membrane filters. The data used are typical of the coastal waters of inland and marginal seas and the open ocean and cover the range of three and two orders of magnitude for the concentrations of CPMM and CPOM, respectively.

Seasonal variation of fluxes of dispersed sedimentary matter in the White Sea (Arctic ocean basin)

The monthly and seasonal quantity estimates of vertical fluxes of sedimentary matter from the White Sea performed during studies are the basis for the direct calculations of incoming chemical components, minerals, and various pollutants to the surface layer of bottom sediments. The White Sea, one of six Russian Arctic seas, may be considered as a megapolygon for further modern research using the new regularities of arctic sedimentogenesis established. This study focuses on the development of new technologies for complex studies of marine water areas using underwater sedimentation observatories, regular observations onboard vessels, and satellite oceanological data. The first priority task is year-round monitoring along the Northern Sea Route.

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.

Dynamics of the main components of fluxes of sedimentary matter in the White Sea

The results of long-term investigations in a small sea of the Arctic Ocean served as a basis for revealing new regularities characteristic of the sedimentary process in the Subarctic and Arctic zones. The monthly, seasonal, and multiyear dynamics of the main components of dispersed sedimentary matter fluxes are analyzed by defining the marine sedimentation stage. It is shown that the biogenic constituent of the flux decreases by an order of magnitude at its transition from dispersed to concentrated forms. The average values of the vertical flux are calculated including the total sedimentary matter and the contribution of main biogenic and terrigenous components per m2 of the bottom and the entire deep area of the White Sea.

Distribution of some rare and trace elements in modern bottom sediments of the Caspian Sea

The features of the distribution of some rare and trace elements in modern bottom sediments of the Caspian Sea have been studied from samples collected during cruises 35, 39, and 41 of the R/V Rift and the cruise of the R/V Nikifor Shurekov in 2013. It was established that bottom sediments in different areas of the Caspian Sea vary to some degree in the contents of Zr, Hf, Th, V, Cr, Co, Ni, Cu, Sr, and Ba in comparison to suspended matter discharged by the Volga River and rivers originating in the Caucasus. As follows from the results of a comparison of the geochemical features of modern bottom sediments of the Volga River delta and different sedimentary subsystems of the Caspian Sea with the chemical composition of Middle Archean granitoids and Paleozoic and Mesozoic–Cenozoic basalts, which are regarded as geochemical images of such provenance areas as the basement of East European Platform, Urals, and Caucasus, none of these regions is considered the dominant provenance area for all sedimentary subsystems of the Caspian Sea region. Here, the revealed similarity between modern bottom sediments of the northern, central and southern Caspian Sea regions, the Volga River delta, and Post-Archean average Australian shale (PAAS) in some parameters, including REE spectra, assumes that the Volga River discharge plays a dominant role in the formation of the geochemical image of Caspian Sea subsystems. The role of clastics, including the fine-grained fraction, which is supplied to the Caspian Sea from the Caucasus region and Elburz Mountains, is insignificant already in the coastal area, which is determined both by influence of the marginal filter (MF) and large-scale cholestatic current circulation.