Dissolved organic carbon investigations from the Kara Sea

Based on observations during four scientific expeditions to the Kara Sea and the Siberian rivers Ob and Yenisei we determined the discharge, distribution and characteristics of dissolved organic matter (DOM). Surface concentrations of dissolved organic carbon (DOC) ranged from 151 IlM C in the northern Kara Sea to 939 IlM C in the river Ob. The estimated annual mean DOC concentration in the Yenisei (681 IlM C) was slightly higher than in the Ob (640 IlM C). Dissolved organic nitrogen (DON) concentrations typically varied between 5 and 15 IlM N with higher values in the rivers. Freshwater discharge and DOC concentrations experienced pronounced seasonal variations strongly affecting the spatial and temporal distribution of DOM in the Kara Sea. The largely conservative distribution of DOC and DON along the salinity gradient indicated the predominantly refractory character of riverine DOM. This observation was consistent with laboratory experiments, which showed only minor losses due to flocculation processes and bacterial consumption. Optical properties and relatively high C/N ratios (19 to 51) of DO M suggest that a large fraction of river DOM is of terrestrial origin and that phytoplankton contributed little to DOM on the Kara Sea shelf during the sampling periods. Together, the rivers Ob and Yenisei discharge about 8 Tg DOC yr- I into the Kara Sea. Due to the absence of efficient removal mechanisms in these estuaries the majority of riverine DOM appears to pass the estuarine mixing zone and is transported towards the Arctic Ocean.

Geochemistry of minerals in CRP sediment cores from the Ross Sea, Antarctica

Sixty-four volcanic chists, sandstones and tephras between 5.95 and 618.19 meters below sea floor (mbsf) in the Cape Roberts Project cores 2 and 2A cores (CRP-2/2A) were examined for Cenozoic and Mesozoic volcanic components, using optical and Scanning Electron Microscopy. Minerals and glass shards in a selection of samples were analysed by electron microprobe fined with an EDAX detector. Laser-Ablation ICP-Mass-Spectrometry (ICP-MS) was used to determine rare earth elements and 14 additional trace elements in glass shards, pyroxenes and feldspars in order to pin-point the onset of McMurdo Volcanic Group (MVG) activity in the stratigraphic column. Pumices in tephra layers of peralkaline phonolite composition in Unit 7.2 -between 108 and 114 mbsf - were also analysed for trace elements by ICP-MS. This tephra unit is not reworked and its isotopic age (21.44 ± 0.05 Ma) is the age of deposition. The height of the eruptive column responsible for the deposition of the tephra was probably less than 8 km; the source was local, probably within 30 km from the drill site. Phonolite of unit 7.2 of CRP-2/2A has no direct petrogenetic relation with the peralkaline trachyte in the tephra-enriched layer of CRP-1 at 116.55 mbsf. Volcanic clasts and sand grains (glass shards, aegirine-augite, anorthoclase) related to Cenozoic activity of MVG were observed only starting from Unit 9.8, where they are dated at 24.22 ± 0.06 Ma at c. 280 mbsf. In this unit the lowest- occurring basaltic glass shard is found at 297.54 mbsf. Sampled McMurdo volcanics are generally vesicular and vary in composition from alkali basalt to trachyte and peralkaline phonolite. By contrast, below 320 mbsf, aphyric or slightly-porphyritic volcanic clasts become more abundant but they are all non-vesiculated, pigeconite and ilmenite-bearing basalts and dolerite of tholeiitic affinity. These rocks are considered to be related to lava flows and associated intrusions of Jurassic age (Kirkpatrick basalts and Ferrar dolerite). As in CRP-1, McMurdo volcanics appear to derive from a variety of lithologics. Besides glaciers, a dominant role of wind transportation from exposed volcanic rocks may be inferred from the contemporary occurrence of glass shards of different compositions at depths above 297.54 mbsf. These data confirm that the onset of magmatic activity in southern Victoria Land is considerably delayed (by about 24 Ma) with respect to northern Victoria Land.

Stable carbon and oxygen isotope record of Cibicidoides from DSDP/ODP holes

High-resolution delta18O records from the equatorial Pacific (site 503B), equatorial Atlantic (site 665A), and North Atlantic (site 606A) based on the benthic foraminifera Cibicidoides wuellerstorfi show the 2.4 Ma onset of major northern hemispheric glaciation to be a package of three events occurring at 2.39, 2.35, and 2.31 Ma in which a periodicity of about 40 kyr is evident. The amplitude of the signals at the three sites indicates that these events were 1/2 to 2/3 the size of the latest Quaternary glaciation and also indicates cooling of northern source bottom water by 2.7°-4.1°C relative to southern source water during glaciations. Carbon isotopes indicate that southern source waters were less oxygenated than in the Quaternary and that there was reduced production of northern source water during glacial intervals. The dominant presence of southern source water in the eastern basin of the equatorial Atlantic, regardless of climatic cycles, throughout the late Pliocene indicates a greater influence of these waters relative to northern source waters in the late Pliocene ocean.

Tab. 1: Muskoxen observed in the different geographical units

Muskoxen populations were surveyed in the course of 3 expeditions to North East Greenland to provide data on present status and habitat requirements in the region between 72 and 74 deg latitude North. The distribution is primarily affected by the snow cover pattern and shows densities from less than 0.1 ind/km**2 to 1.5 ind/km**2. Ranges unutilized by muskoxen prior to 1940 now support high densities. The snow cover influences also the population dynamics, as shown by the streng correlation between the calf crop and the amount of snow. The total population is estimated to be about 1000 to 1500 individuals far the whole region.

Chemical composition of volcanic glass of some tephra layers in Northeastern Pacific Ocean

Five widespread upper Cenozoic tephra layers that are found within continental sediments of the western United States have been correlated with tephra layers in marine sediments in the Humboldt and Ventura basins of coastal California by similarities in major-and trace-element abundances; four of these layers have also been identified in deep-ocean sediments at DSDP sites 34, 36, 173, and 470 in the northeastern Pacific Ocean. These layers, erupted from vents in the Yellowstone National Park area of Wyoming and Idaho (Y), the Cascade Range of the Pacific Northwest (C), and the Long Valley area, California (L), are the Huckleberry Ridge ash bed (2.0 Ma, Y), Rio Dell ash bed (ca. 1.5 Ma, C), Bishop ash bed (0.74 Ma, L), Lava Creek B ash bed (0.62 Ma, Y), and Loleta ash bed (ca. 0.4 Ma, C). The isochronous nature of these beds allows direct comparison of chronologic and climatic data in a variety of depositional environments. For example, the widespread Bishop ash bed is correlated from proximal localities near Bishop in east-central California, where it is interbedded with volcanic and glacial deposits, to lacustrine beds near Tecopa, southeastern California, to deformed on-shore marine strata near Ventura, southwestern California, to deep-ocean sediments at site 470 in the eastern Pacific Ocean west of northern Mexico. The correlations allow us to compare isotopic ages determined for the tephra layers with ages of continental and marine biostratigraphic zones determined by magnetostratigraphy and other numerical age control and also provide iterative checks for available age control. Relative age variations of as much as 0.5 m.y. exist between marine biostratigraphic datums [for example, highest occurrence level of Discoaster brouweri and Calcidiscus tropicus (= C. macintyrei)], as determined from sedimentation rate curves derived from other age control available at each of several sites. These discrepancies may be due to several factors, among which are (1) diachronism of the lowest and highest occurrence levels of marine faunal and floral species with latitude because of ecologic thresholds, (2) upward reworking of older forms in hemipelagic sections adjacent to the tectonically active coast of the western United States and other similar analytical problems in identification of biostratigraphic and magnetostratigraphic datums, (3) dissolution of microfossils or selective diagenesis of some taxa, (4) lack of precision in isotopic age calibration of these datums, (5) errors in isotopic ages of tephra beds, and (6) large variations in sedimentation rates or hiatuses in stratigraphic sections that result in age errors of interpolated datums. Correlation of tephra layers between on-land marine and deep-ocean deposits indicates that some biostratigraphic datums (diatom and calcareous nannofossil) may be truly time transgressive because at some sites, they are found above and, at other sites, below the same tephra layers.

Table 3: Comparison of freshwater species in Ob and Yenisei during the 1997 cruise

Phytoplankton biomass distribution (chlorophyll a, chl. a) and species composition (cell numbers) were investigated during three expeditions to the Kara Sea with "Akademik Boris Petrov" (BP) in 1997, 1999, and 2000. The distribution of biomass in the estuaries of Ob and Yenisei showed a similar range in 1997 (0.2 to 3.2 µg/l) and 2000 (0.4 to 3.5 ug/l); higher chl. a concentrations during these two years were found in Yenisei than in Ob. In 1999, phytoplankton biomass in the Ob and Ob Estuary was much higher than in 1997 and 2000, with maximum values above 10.0 ug chl. a/l. In 1999, biomass in Yenisei was lower (1.5 to ~5 ug/l) than in Ob but slightly higher than in 1997 and in 2000. During the expedition in 2000, the research area extended farther to the north, here, lowest phytoplankton biomass during all three years was found. Typical summer values for integrated chl.a biomass (surface to bottom) ranged between 6 and 20 mg m**-2. Strong differences existed in species composition in both rivers, the estuaries, and the open Kara Sea. In general, three or four different populations could be distinguished in surface waters: (1) freshwater diatoms together with bluegreen algae in both rivers, (2) centric and small pennate diatoms mainly brackish species in the estuaries, (3) north of 74°N, brackish/marine species dominated, i.e. in 1999 Thalassiosira cfpunctigera and Chaetoceros spp prevailed in the phytoplankton bloom in Ob. (4) At the northernmost, almost marine stations, a region with a more heterogeneous composition of unicellular plankton was encountered. We assume, we found different seasonal signals of phytoplankton development during 1997/2000 and 1999, respectively. However, the yearly fluctuation of freshwater runoff of both rivers seems to have the strongest influence on the timing and duration of phytoplankton blooms, species compositions and biomass standing stocks during summer.

(Table 1) Tagging date, total length and sex of bowhead whales (Balaena mysticetus) tagged at Point Barrow, Alaska

Working with subsistence whale hunters, we tagged 19 mostly immature bowhead whales (Balaena mysticetus) with satellite-linked transmitters between May 2006 and September 2008 and documented their movements in the Chukchi Sea from late August through December. From Point Barrow, Alaska, most whales moved west through the Chukchi Sea between 71° and 74° N latitude; nine whales crossed in six to nine days. Three whales returned to Point Barrow for 13 to 33 days, two after traveling 300 km west and one after traveling ~725 km west to Wrangel Island, Russia; two then crossed the Chukchi Sea again while the other was the only whale to travel south along the Alaskan side of the Chukchi Sea. Seven whales spent from one to 21 days near Wrangel Island before moving south to northern Chukotka. Whales spent an average of 59 days following the Chukotka coast southeastward. Kernel density analysis identified Point Barrow, Wrangel Island, and the northern coast of Chukotka as areas of greater use by bowhead whales that might be important for feeding. All whales traveled through a potential petroleum development area at least once. Most whales crossed the development area in less than a week; however, one whale remained there for 30 days.

Chemical composition of rocks and minerals from the Mid-Atlantic Ridge near 15°20'N

The monograph summarizes results of petrological and geochemical studies of rocks from the ocean floor collected by the authors during expeditions to the Central Atlantic. Detailed work in the Capa Verde transform fault zone gave a large amount of new information about magmatic and hydrothermal systems of the Mid-Atlantic Ridge.

Grain size composition of 275 sediment profiles from the Arctic seas

This data set contains grain size analyses of bottom sediments collected by scientists from the V.P. Zenkovich Laboratory of Shelf and Sea Coasts (P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences) during the Project ''Arctic Shelf of the Eurasia in the Late Quaternary'' in a number of expeditions to the Barents, Kara, East Siberian and Chukchi Seas on board the research vessels R/V Professor Shtokman, H/V Dmitry Laptev, H/V Malygin, and icebreaker Georgy Sedov since 1978. The analyses have been carried out according to the methods published by Petelin (1967) in the Analytical Laboratory of the P.P. Shirshov Institute of Oceanology. Archiving and electronic publication was performed through a data rescue by Evgeny Gurvich in 2003.

Mineral composition of 356 sediment profiles from the Arctic seas

This data set contains the mineralogical analyses (binocular counting) of the 100-50 µm grain size fraction from bottom sediments collected by scientists of the V.P. Zenkovich Laboratory of Shelf and Sea Coasts (P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences) during the Project ''Arctic Shelf of the Eurasia in the Late Quaternary'' in a number of expeditions to the Barents, Kara, East Siberian and Chukchi Seas on board research vessels R/V Professor Shtokman, H/V Dmitry Laptev, H/V Malygin, and icebreaker Georgy Sedov between 1978 and 1990. The analyses have been carried out according to the methods published by Petelin V.P. (1961) in the Analytical Laboratory of the P.P. Shirshov Institute of Oceanology. Archiving and electronic publication was performed through a data rescue by Evgeny Gurvich in 2003.

Chemical composition of 169 sediment profiles from the Arctic seas

This data set contains chemical composition of bottom sediments collected by scientists from the V.P. Zenkovich Laboratory of Shelf and Sea Coasts (P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences) during the Project ''Arctic Shelf of the Eurasia in the Late Quaternary'' in a number of expeditions to the Barents, Kara, East Siberian and Chukchi Seas on board research vessels R/V Professor Shtokman, H/V Dmitry Laptev, H/V Malygin, and icebreaker Georgy Sedov between 1978 and 1990. The analyses have been carried out in the Analytical Laboratory of the P.P. Shirshov Institute of Oceanology. Archiving and electronic publication was performed through a data rescue by Evgeny Gurvich in 2003.