I. A. Nemirovskaya

Origin of hydrocarbons in the particulate matter and bottom sediments of the northern shelf of the Caspian Sea

Data are presented on the content and composition of hydrocarbons (HC) (aliphatic, AHC and polyaromatic, PAH) in the filtered particulate matter and in the surface layer of the bottom sediments on the northern shelf of the Caspian Sea and related to the data on their content in the Volga River estuary. Because of the transformation and precipitation of anthropogenic and natural compounds, the HC composition in the particulate matter and bottom sediments undergoes transformations caused by the mixing of fresh and saline waters (in the bottom sediments, within the concentration ranges 70.4–4557.9 μ g/g for AHC and 3.8–4800 ng/g for PAH). It was found that the greatest concentrating of HC proceeds in the region of the avalanche sedimentation, and their content is independent of the grain-size type of the sediments. The anthropogenic HC (oil and pyrogenous) do not get over the marginal filter of the Volga River and do not pass to the open part of the sea.

The concentration and composition of hydrocarbons in water, particulate matter, and bottom sediments of the Kara Sea

Data are presented on the content of aliphatic and polycyclic aromatic hydrocarbons (AHC and PAH, respectively) in the interstitial waters and bottom sediments of the Kara Sea compared to the distribution of the particulate matter and organic carbon. It was found that the AHC concentrations within the water mass (16 μg/l on average) are mainly formed by natural processes. The AHC distribution represents the variability of the hydrological and sedimentation processes in different regions of the sea. The widest ranges of the concentrations were registered in the Ob Bay-Kara Sea section: in the water (10–310 μg/l for the AHC and 0.4–7.2 ng/l for the PAH) and in the surface layer of the bottom sediments (8–42 μg/l for the AHC and 9–94 ng/g for the PAH). The differentiation of the hydrocarbons (HC) in the different media follows the marginal filter’s regularities; therefore, no oil and pyrogenic compounds are supplied to the open parts of the sea. In the sediment mass, the HC content is determined by the variations in the oxidative conditions in the sediment and its material’s composition.

Particulate matter and components of the organic substance in the surface waters of the Southern and Atlantic Oceans

The integrated studies of the particulate matter and organic compounds in the surface waters and the snow-ice cover by means of geochemical (the concentrations of the particulate matter, the Corg, the hydrocarbons, the lipids, and the chlorophyll a) and optical techniques were performed in the Southern Ocean and in the east of the Atlantic Ocean along the vessel’s route: Africa-Antarctica-Africa-St. Petersburg. The correlations between the treated compounds were found. It was shown that the supply of pollutants affects not only the concentrations but also the proportions of the considered compounds. New data were obtained on the processes of the accumulation of particulate matter and organic compounds under the ice formation.

Peculiarities in the distribution of hydrocarbons in the southeastern part of the Baltic Sea

Data on the contents and compositions of the hydrocarbons (HCs)—aliphatic (AHCs) and polycyclic aromatic (PAHs)—are provided in comparison with the contents of the total organic carbon (Corg), the lipids in the particulates, and the Corg in bottom sediments. Particular attention has been paid to the distribution of the HCs in the water area of the Kravtsov oil field. It has been established that the concentrations of AHCs in the water are governed by the content of particulates, and the elevated AHC concentrations are confined to the coastal areas. In the water area of platform D-6, the sandy bottom sediments were notable for the great variability of the HC concentrations, both laterally and from year to year. In the summer of 2010, the content of AHCs averaged 40 μg/g (19% in the Corg), and that of PAHs, 23 ng/g. Natural seepage from the sediment mass is considered to be a source of HCs along with oil contamination.

Variability of suspended particulate matter concentrations and organic compounds in frontal zones of the Atlantic and Southern oceans

The concentrations of suspended particulate matter (SPM) and particulate forms of the organic compounds (hydrocarbons, lipids, and chlorophyll a) were determined in the surface water layers of the Atlantic and Southern oceans during February to May of 2012 and 2014. It was found that the distribution of concentrations of the studied components is mainly affected by the location of frontal zones. When ice cover forms in the Southern Ocean, the changes in water temperature and phytoplankton development at the ice–water interface result in an increase of the concentrations of SPM, chlorophyll a, and, to a lesser extent, of lipids and hydrocarbons in the surface water layer. The occasional sharp increase of hydrocarbon concentrations caused by anthropogenic pollution was registered at local parts of water areas in the east of the Atlantic Ocean, as well as in the North and Baltic seas.

Variability of concentration and composition of hydrocarbons in frontal zones of the Kara Sea

The distribution and composition of aliphatic and polycyclic aromatic hydrocarbons (HC) in dissolved and particulate forms, as well as in bottom sediments, was studied along the route of a vessel and at stations. It was found that the widest variability of HC concentrations in surface waters was characteristic for the frontal zones of the Yenisei River mouth (4.8–69 µg/L) and for the western branch of the St. Anna Trough (5.5–80.4 µg/L). The increased concentrations of aliphatic HC coincide with those of chlorophyll and particulate matter, as well as with the growth of the intensity of fluorescence, and are caused by natural processes. This is confirmed by HC composition. Bottom sediments are characterized by low HC concentrations, both in terms of dry mass (14 µg/g on average, with the maximum of 36.8 µg/g at station 5018 in the layer of 3–17 cm) and within Corg compositions (0.88%). Natural terrigenous homologues are prevailing in alkane composition of the sediments. The marginal filters of the Ob and Yenisei rivers were compared. It is shown that oil HC transferred by the rivers are deposited in the zone of marginal filters without reaching the open waters of the Kara Sea.

Hydrocarbons in the snow-ice cover of different areas of the White Sea

The data on the content of hydrocarbons (HC) are presented and compared to the contents of organic carbon, lipids, and particulate matter in the snow-ice cover of the coastal areas of Dvina and Kandalaksha bays of the White Sea (2008–2012). The accumulation of HC in the snow-ice cover depends on the degree of atmosphere contamination, the conditions of the ice formation, and the intensity of the biogeochemical processes at the ice-water interface. Because of this, the aquatic area of Arkhangelsk is characterized by the highest HC concentrations in the snow and in the upper layer of ice. The peculiarities of the formation of the snow-ice cover in Rugozero bight of Kandalaksha Bay cause the concentrating of HC in different layers of ice. The decrease of the concentration of HC in the show-ice cover of the White Sea compared to earlier studies resulted from the recession of industrial activities during the recent years.

Studies of hydrocarbons in the waters and snow-ice cover of the southeast sector of the antarctic

Data are presented on the content of hydrocarbons (HC) relative to the concentrations of particulate matter, lipids, Corg, and chlorophyll a in the surface waters and snow-ice cover of the East Antarctic coastal areas. It was shown that the growth of the concentrations of aliphatic HC (AHC) to 30 μg/l in the surface waters takes place in the frontal zones and under the young ice formation. The AHC content in the snow increases with the growth of the aerosol content in the atmosphere. In the lower part of the ice at the boundary with the seawater, despite the low temperatures, the autochthonous processes may provide high AHC concentrations (up to 289 μg/l). Within the snow-ice cover on fast ice, synchronous content variations of all the compounds considered take place.

Associated studies during the voyage of the R/V Akademik Nikolai Strakhov

Surface water samples were taken during the voyage of the R/V Akademik Nikolai Strakhov (December 2015–January 2016) from the port of Colombo through Indian Ocean, Red Sea, Mediterranean Sea, Atlantic Ocean, North Sea, and Baltic Sea through the Great Belt (figure). The aim of this work was to examine the effect of specific climate features and frontal zones on the distribution of suspended matter in the surface water layer as well as the distribution of organic matter in this suspension, including lipids, hydrocarbons (HCs), and chlorophyll a (chl a). The route of the vessel covered tropical, subtropical, and moderate zones in the humid and arid regions of the oceans. Suspensions and organic matter were assayed by routine methods used in oceanology. The lowest concentrations of suspended matter were observed in the Indian Ocean and Mediterranean Sea, where its content reached 1 mg/L only in some surface water samples (figure). Elevated concentrations of suspended matter were observed in the exit of the Red Sea (9.53 mg/L) and reached the maximum level by the North Sea (15.92 mg/L). The average conINFORMATION

Research during the 47th cruise of the research vessel Akademik Ioffe

During the 47th cruise of the R/V Akademik Ioffe on its route from the port of Ushuaia to the port of Gdansk, studies were conducted of the near-water atmospheric layer and surface water layer from March 26 to May 7, 2015 for the purpose of determining the influence of the climatic pattern and frontal zones of the Atlantic Ocean on the distribution of aerosols, suspended particulate matter (SPM) and organic compounds (including contaminants). Similar studies (which, however, had been on a smaller scale) were carried out 10 years ago in 2005 during the 20th cruise of the R/V Akademik Sergei Vavilov. The route of the 47th cruise of the R/V Akademik Ioffe was different from the previous ones by its passing westward from Cape Verde and the Canary Islands.