(Table 1) Results of measurements of production characteristics of phytoplankton and some physical parameters of the environment in the northeastern Norwegian Sea in July 1995

From July 4 to 18,1995 surface chlorophyll a concentrations (C_cs) and integral primary production (C_ps) were studied in the northeastern part of the Norwegian Sea (73°42'N; 13°16'E), over a test area where an accident of the nuclear submarine Komsomolets had taken place. It was found that during this interval C_cs decreased by factor of about 3.3 (from 0.78 to 0.24 mg/m**3); average chlorophyll concentration within the photo-synthetic layer (C_cl) decreased by factor of about 3.5 (from 0.97 to 0.28 mg/m**3). The value of C_ps in the water column varied slightly (from 445 to 539 mg C/m**2 per day), since decrease in C_cl was compensated both by 1.5-fold growth of the photosynthetic layer thickness (from 40 to 60 m) and by 2.1-fold increase in its average assimilation number (from 0.58 to 1.20 mg C/mg chl a per hour). Monthly averages of C_ps were obtained from published data on seasonal C_cs changes and on the level of incident solar irradiation. They were found to be less than 100 mg C/m**2 per day in March and October and 100-500 mg C/m**2 per day in April-June. Annual primary production calculated from above values was equal to 105 g C/m**2.

Glacier mass balance measurements on Fourcade and Polar Club glacier, King George Island

The east coast of the AP is highly influenced by cold and dry air masses stemming from the adjacent Weddell Sea. By the contrary, the west coast jointly with the South Shetland Islands are directly exposed to the humid and relatively warm air masses from the South Pacific Ocean carried by the strong and persistent westerly winds. Systematic glaciological field studies are very scarce on both sides of the AP, among them can be mentioned a mass-balance program performed continuously since summer 1998/99 by the Instituto Antártico Argentino (IAA) on Vega Island, James Ross Archipelago, on the northeastern flank of the AP. Another continuous plurianual glaciological research has been initiated in 2010 jointly by the University of Bonn and the IAA at the Fourcade Glacier on King George Island (KGI) within the framework of the ESF project IMCOAST (FK 03F0617B). Two transects of mass balance stakes were installed from the top of the Warszawa Ice Dome down to the border of the glaciers Fourcade and Polar Club, to serve for calibration and validation of modeling efforts. The stakes were measured at the beginning and end of each summer field campaign in November 2010, February - March 2011, January - March 2012, and especially during the austral winter 2012 up to March 2013 every 10 to 14 days depending on weather conditions. During the austral winter 2013 and until June 2014 the measurements were conducted every 20 to 30 days, weather permitting. Snow density was measured as well in every field trip from June 2012 until June 2104, establishing a rather homogeneous value along the different parts of the glacier. Snow density in late summer, rho_s is usually higher than the one in late winter, rho_w. Seasonal average values were calculated for the area covered by the mass balance stakes, being rho_s= 471 Kg/m**3 and rho_w = 363 Kg/m**3.

Ice thickness measurements in the Lincoln Sea and adjacent Arctic Ocean

Results of helicopter-borne electromagnetic measurements of total (ice plus snow) sea-ice thickness performed in May 2004 and 2005 in the Lincoln Sea and adjacent Arctic Ocean up to 86° N are presented. Thickness distributions south of 84° N are dominated by multi-year ice with modal thicknesses of 3.9 m in 2004 and 4.2 m in 2005 (mean thicknesses 4.67 and 5.18 m, respectively). Modal and mean snow thickness on multi-year ice amounted to 0.18 and 0.30 m in 2004, and 0.28 and 0.35 m in 2005. There are also considerable amounts of 0.9-2.2 m thick first-year ice (modal thickness), mostly representing ice formed in the recurring, refrozen Lincoln Polynya. Results are in good agreement with ground-based electromagnetic thickness measurements and with ice types demarcated in satellite synthetic aperture radar imagery. Four drifting buoys deployed in 2004 between 86° N and 84.5° N show a similar pattern of a mean southward drift of the ice pack of 83 ± 18 km between May 2004 and April 2005, towards the coast of Ellesmere Island and Nares Strait. The resulting area decrease of 26% between the buoys and the coast is larger than the observed thickness increase south of 84° N. This points to the importance of shear in a narrow band along the coast, and of ice export through Nares Strait in removing ice from the study region.

Biogeochemical measurements associated to deep-sea wood falls

Large organic food falls to the deep sea - such as whale carcasses and wood logs - support the development of reduced, sulfidic niches in an otherwise oxygenated, oligotrophic deep-sea environment. These transient hot spot ecosystems may serve the dispersal of highly adapted chemosynthetic organisms such as thiotrophic bivalves and siboglinid worms. Here we investigated the biogeochemical and microbiological processes leading to the development of sulfidic niches. Wood colonization experiments were carried out for the duration of one year in the vicinity of a cold seep area in the Nile deep-sea fan (Eastern Mediterranean) at depths of 1690 m. Wood logs were deployed in 2006 during the BIONIL cruise (RV Meteor M70/2 with ROV Quest, Marum, Germany) and sampled in 2007 during the Medeco-2 cruise (RV Pourquoi Pas? with ROV Victor 6000, Ifremer, France). Wood-boring bivalves played a key role in the initial degradation of the wood, the dispersal of wood chips and fecal matter around the wood log, and the provision of colonization surfaces to other organisms. Total oxygen uptake measured with a ROV-operated benthic chamber module was higher at the wood (0.5 m away) in contrast to 10 m away at a reference site (25 mmol m-2 d-1 and 1 mmol m-2 d-1, respectively), indicating an increased activity of sedimentary communities around the wood falls. Bacterial cell numbers associated with wood increased substantially from freshly submerged wood to the wood chip/fecal matter layer next to the wood experiments, as determined with Acridine Orange Direct Counts (AODC) and DAPI-stained counts. Microsensor measurements of sulfide, oxygen and pH were conducted ex situ. Sulfide fluxes were higher at the wood experiments when compared to reference measurements (19 and 32 mmol m-2 d-1 vs. 0 and 16 mmol -2 d-1, respectively). Sulfate reduction (SR) rates at the wood experiments were determined in ex situ incubations (1.3 and 2.0 mmol m-2 d-1) and fell into the lower range of SR rates previously observed from other chemosynthetic habitats at cold seeps. There was no influence of wood deposition on phosphate, silicate and nitrate concentrations, but ammonium concentrations were elevated at the wood chip-sediment boundary layer. Concentrations of dissolved organic carbon were much higher at the wood experiments (wood chip-sediment boundary layer) in comparison to measurements at the reference sites, which may indicate that cellulose degradation was highest under anoxic conditions and hence enabled by anaerobic benthic bacteria, e.g. fermenters and sulfate reducers. Our observations demonstrate that, after one year, the presence of wood at the seafloor had led to the creation of sulfidic niches, comparable to what has been observed at whale falls, albeit at lower rates.

Static GPS measurements in the vicinity of EDML and an elevation model for Dronning Maud Land

The knowledge of ice sheet surface topography and the location of the ice divides are essential for ice dynamic modeling. An improved digital elevation model (DEM) of Dronning Maud Land (DML), Antarctica, is presented in this paper. It is based on ground-based kinematic GPS profiles, airborne radar altimetry, and data of the airborne radio-echo sounding system, as well as spaceborne laser altimetry from NASA's Ice, Cloud and land Elevation Satellite (ICESat). The accuracy of ICESat ice sheet altimetry data in the area of investigation is discussed. The location of the ice divides is derived from aspect calculation of the topography and is verified with several velocity data derived from repeated static GPS measurements.

Radiocarbon ages and stable isotope measurements on sediment cores of the subarctic Pacific and its marginal seas

Under modern conditions only North Pacific Intermediate Water is formed in the northwest Pacific Ocean. This situation might have changed in the past. Recent studies with general circulation models indicate a switch to deep-water formation in the northwest Pacific during Heinrich Stadial 1 (17.5-15.0 ka) of the last glacial termination. Reconstructions of past ventilation changes based on paleoceanographic proxy records are still insufficient to test whether a deglacial mode of deep-water formation in the North Pacific Ocean existed. Here we present deglacial ventilation records based on radiocarbon-derived ventilation ages in combination with epibenthic stable carbon isotopes from the northwest Pacific including the Okhotsk Sea and Bering Sea, the two potential source regions for past North Pacific ventilation changes. Evidence for most rigorous ventilation of the intermediate-depth North Pacific occurred during Heinrich Stadial 1 and the Younger Dryas, simultaneous to significant reductions in Atlantic Meridional Overturning Circulation. Concurrent changes in d13C and ventilation ages point to the Okhotsk Sea as driver of millennial-scale changes in North Pacific Intermediate Water ventilation during the last deglaciation. Our records additionally indicate that changes in the d13C intermediate-water (700-1750 m water depth) signature and radiocarbon-derived ventilation ages are in antiphase to those of the deep North Pacific Ocean (>2100 m water depth) during the last glacial termination. Thus, intermediate- and deep-water masses of the northwest Pacific have a differing ventilation history during the last deglaciation.