Concentrations of organic compounds in suspended matter from surface waters and surface layer bottom sediments of the Obskay Guba (Ob River estuary) and the Kara Sea

Data are presented on concentrations of aliphatic and polycyclic aromatic hydrocarbons (AHC and PAH) in interstitial waters and bottom sediments of the Kara Sea compared to distribution of particulate matter and organic carbon. It was found that AHC concentrations within the water mass (aver. 16 µg/l) are mainly formed by natural processes. Distribution of AHC represents variability of hydrological and sedimentation processes in different regions of the sea. The widest ranges of the concentrations occurred in the Obskaya Guba - Kara Sea section: in water (10-310 µg/l for AHC and 0.4-7.2 ng/l for PAH) and in the surface layer of the bottom sediments (8-42 µg/l for AHC and 9-94 ng/g for PAH). Differentiation of hydrocarbons (HC) in different media follows regularities typical for marginal filters; therefore no oil and pyrogenic compounds are supplied to the open sea. In sediments contents of HC depend on variations in redox conditions in sediments and on their composition.

Metamorphic processes in sediments at DSDP Leg 65 Holes

Sites 482, 483, and 485 were drilled during Leg 65 on young oceanic crust south of the Tamayo Transform Fault. The Leg 65 drilling program was part of a multinational effort to study the East Pacific Rise (EPR) and complements sea bottom surveys conducted both in this area (Lewis, 1979; Cyamex Scientific Team and Pastouret, 1981) and farther south at 21 °N (Larson, 1971; Normark, 1976; Cyamex Scientific Team; Rise Project Group, 1980). These studies, which included deep-tow, Angus and submersible surveys, were recently complemented by sea-beam surveys conducted by the Jean Charcot on the Tamayo Fracture Zone and farther south along the EPR. They have led to a better understanding of the magmatic, tectonic, and sedimentary processes occurring on the East Pacific Rise between the Tamayo and Rivera fracture zones. The purpose of this chapter is to describe the metamorphic processes affecting Pliocene through Quaternary sediments found in contact, or inter layered, with basaltic units drilled during Leg 65 at the mouth of the Gulf of California.

Sulfur and carbon in mIcrobial processes in waters and sediments of the Kara Sea in September 2007

Results of microbiological, biogeochemical and isotope geochemical studies in the Kara Sea are described. Samples for these studies were obtained during Cruise 54 of R/V Akademik Mstislav Keldysh in September 2007. The studied area covered the northern, central, and southwestern parts of the Kara Sea and the Obskaya Guba (Ob River estuary). Quantitative characteristics of total bacterial population and activity of microbial processes in the water column and bottom sediments were obtained. Total abundance of bacterioplankton (BP) varied from 250000 cells/ml in the northern Kara Sea to 3000000 cells/ml in the Obskaya Guba. BP abundance depended on concentration of suspensded matter. Net BP production was minimal in the central Kara Sea (up to 0.15-0.2 µg C/l/day) and maximal (0.5-0.75 µg C/l/day) in the Obskaya Guba. Organic material at the majority of stations at the Ob transect predominantly contained light carbon isotopes (-28.0 to -30.18 per mil) of terrigenous origin. Methane concentration in the surface water layer varied from 0.18 to 2.0 µl CH4/l, and methane oxidation rate varied from 0.1 to 100 nl CH4/l/day. Methane concentration in the upper sediment layer varied from 30 to 300 µl CH4/dm**3; rate of methane formation was varied from 44 to 500 nl CH4/dm**3/day and rate of methane oxidation - from 30 to 2000 nl CH4/dm**3/day. Rate of sulfate reduction varied from 4 to 184 µg S/dm**3/day.

Biogeochemical parameters and processes in waters and bottom sediments of the Chukchi Sea

Study of biogeochemical processes in waters and sediments of the Chukchi Sea in August 2004 revealed atypical maxima of biogenic element (N, P, and Si) concentrations and rate of microbial sulfate reduction in the surface layer (0-3 cm) of marine sediments. The C/N/P ratio in organic matter (OM) of this layer does not fit the Redfield-Richards stoichiometric model. Specific features of biogeochemical processes in the sea are likely related to the complex dynamics of water, high primary produc¬tivity (110-1400 mg C/m**2/day), low depth of the basin (<50 m for 60% of the water area), reduced food chain due to low population of zooplankton, high density of zoobenthos (up to 4230 g/m**2), and high activity of microbial processes. Drastic decrease in concentrations of biogenic elements, iodine, total alkalinity, and population of microorganisms beneath the 0-3 cm layer testify to large-scale OM decay at the water-seafloor barrier. Our original experimental data support high annual rate of OM mineralization at the bottom of the Chukchi Sea.

Protein and organic phosphorus in particulate matter and mesoplankton fraction in waters of the East Pacific

Vertical distribution of organic phosphorus and phosphatase activity was studied in the Southeast Pacific Ocean. The average rate of mineralization of organic phosphorus in the 0-200 m layer was shown to differ by a factor of 5-10 in oligotrophic and eutrophic areas, while residence time of phosphorus in production-destruction cycles differed by a factor of only 2-5, apparently because of both concentration of organic phosphorus and phosphorolysis rate increased simultaneously in the areas.

(Table 2) Contents of chlorophyll a, organic carbon, nitrogen, and phosphorus and their molar ratios in dried matter of Ahnfeltia tobuchiensis agar containing seaweed from the Izmena Bay, Kunashir Island (South Kurils)

A complex study of influence of various environmental factors on rates of oxygen (M_O2 ), ammonium (M_NH4), and phosphate (M_PO4) metabolism in Ahnfeltia tobuchiensis has been carried out in situ in the Izmena Bay of the Kunashir Island. The following environmental factors have been included into the investigation: photosynthetically active radiation (PAR); ammonium (NH4); phosphate (PO4); and contents of carbon (C), nitrogen (N), phosphorus (P), and chlorophyll a (Chl) in tissue. Population of agar-containing seaweed A. tobuchiensis forms a layer with thickness up to 0.5 m, which occupies about 23.3 km**2; biomass is equal to 125000 tons. Quantitative assessment of organic matter production and nutrient consumption during oxygen metabolism has been carried out for the whole population. It has been shown that daily oxygen metabolism depends on PAR intensity, concentrations of PO4 and NH4 in seawater, and contents of N and P in tissues (r**2=0.78, p<0.001). Average daily NH4 consumption is 0.21 µmol/g of dry weight/hour and depends on NH4 and O2 concentrations in seawater and on ? and Chl a contents in algal tissues (r**2=0.64, p<0.001). Average daily PO4 consumption is 0.01 µmol/g of dry weight/hour and depends on NH4 concentrations in seawater and on P contents in algal tissues (r**2=0.40, p<0.001).

Relative contents of principal diatom groups in suspended matter and surface layer bottom sediments from the Indian Ocean

Data on relative contents of principal diatom groups in suspended matter collected by a separator on the way of the ship and in bottom sediments from different areas of the Indian Ocean are presented in the paper.