Inorganic carbon and geochemistry measurements from landfast sea ice in Resolute Passage, Nunavut, Canada, as part of the Arctic-ICE project, May - June 2010

We conducted a six-week investigation of the sea ice inorganic carbon system during the winter-spring transition in the Canadian Arctic Archipelago. Samples for the determination of sea ice geochemistry were collected in conjunction with physical and biological parameters as part of the 2010 Arctic-ICE (Arctic - Ice-Covered Ecosystem in a Rapidly Changing Environment) program, a sea ice-based process study in Resolute Passage, Nunavut. The goal of Arctic-ICE was to determine the physical-biological processes controlling the timing of primary production in Arctic landfast sea ice and to better understand the influence of these processes on the drawdown and release of climatically active gases. The field study was conducted from 1 May to 21 June, 2010.

Composition of aerosols collected in the Western Russian Arctic in August-September 1991

In August-September 1991 during the SPASIBA expedition (Scientific Program on the Arctic and Siberian Aquatorium) aboard R/V Yakov Smirnitzky in the Laptev Sea ten samples of aerosols were collected by nylon nets. A combined approach including various analytical techniques, such as single-particle analysis, instrumental neutron activation analysis, and atomic absorption spectrophotometry, was used to study composition of the samples. Mass concentration of coarse-grained (>0.001 mm) insoluble fraction of aerosols ranged from 80 to 460 ng/m**3. In all the samples remains of land vegetation were found to be the dominant component. Organic carbon content of the aerosols ranged from 23 to 49%. Inorganic part of the samples was represented mainly by alumosilicates and quartz. Anthropogenic ''fly ash'' particles were observed in all the samples. Temporal variations of element concentrations resulted from differences in air masses entering the studied area.

Chemical composition of bulk sediments from ODP Hole 199-1215A

Elemental concentrations were determined on 21 samples from Hole 1215A to evaluate the influence of hydrothermal sources on bulk sediment composition. Rare earth element (REE) concentrations were also determined on 10 of these samples. Concentration profiles and REE patterns are consistent with a strong hydrothermal influence on sediment composition at the base of Hole 1215A.

Geochemistry at DSDP Leg 75 Holes

Samples of sediments and rocks collected at DSDP Sites 530 and 532 were analyzed for 44 major, minor, and trace elements for the following purposes: (1) to document the downhole variability in geochemistry within and between lithologic units; (2) to document trace-element enrichment, if any, in Cretaceous organic-carbon-rich black shales at Site 530; (3) to document trace-element enrichment, if any, in Neogene organic-carbon-rich sediments at Site 532; (4) to document trace-element enrichment, if any, in red claystone above basalt basement at Site 530 that might be attributed to hydrothermal activity or weathering of basalt. Results of the geochemical analyses showed that there are no significant enrichments of elements in the organic-carbon-rich sediments at Site 532, but a number of elements, notably Cd, Co, Cr, Cu, Mo, Ni, Pb, V, and Zn, are enriched in the Cretaceous black shales. These elements have different concentration gradients within the black-shale section, however, which suggests that there was differential mobility of trace elements during diagenesis of interbedded more-oxidized and less-oxidized sediments. There is little or no enrichment of elements from hydrothermal activity in the red claystone immediately overlying basalt basement at Site 530, but slight enrichments of several elements in the lowest meter of sediment may be related to subsea weathering of basalt

Zooplankton and seston in the White Sea and its chemical composition

A technique of zooplankton net sampling at night in the Kandalaksha and Dvinskii Bays and during the full tide in the Onezhskii Bay of the White Sea allowed us to obtain "clean" samples without considerable admixtures of terrigenous particulates. Absence of elements-indicators of the terrigenous particulates (Al, Ti, and Zr) in the EDX spectra allows to conclude that ash composition of tested samples is defined by constitutional elements comprising organic matter and integument (chitin, shells) of plankton organisms. A quantitative assessment of accumulation of ca. 40 chemical elements by zooplankton based on a complex of modern physical methods of analysis is presented. Values of the coefficient of the biological accumulation of the elements (Kb) calculated for organic matter and the enrichment factors (EF) relative to Clarke concentrations in shale are in general determined by mobility of the chemical elements in aqueous solution, which is confirmed by calculated chemical speciation of the elements in the inorganic subsystem of surface waters of Onezhskii Bay.

Temperature dependent growth and inorganic ion composition of haemolymph of juvenile Sepia officinalis, 2006

B Body wet weight and mantle length of juvenile Sepia officinalis were monitored over a peroid of five weeks. The animals had hatched in our aquarium system in Bremerhaven, Germany at 16°C and were descendants of individuals collected in the Oosterschelde estuary, Netherlands. Animals were kept in natural sea water at 10 or 17°C and fed small live shrimp (Palaemonetes varians) ad libitum daily. At the end of the experiment some animals kept at 17°C were sacrificed using ethanol. Haemolymph was withdrawn from the head vein using syringe and needle. Haemolymph samples were stored at -20°C until Na+, Cl-, K+, Mg2+, Ca2+ and SO42- concentrations were determined using ion chromatography. Mean body weight more that tripled at 17°C during the investigation period, while growth was impared by exposue to 10°C. Haemolymph ion concentrations were similar to those in sea water, except for sulphate. The concentration of this ion in the haemolymph was more that ten times lower than in sea water.

Measurements of trace metal abundances and isotopes in carbonate sediments, Exuma, Bahamas

In order to validate the use of 238U/235U as a paleoredox proxy in carbonates, we examined the incorporation and early diagenetic evolution of U isotopes in shallow Bahamian carbonate sediments. Our sample set consists of a variety of primary precipitates that represent a range of carbonate producing organisms and components that were important in the past (scleractinian corals, calcareous green and red algae, ooids, and mollusks). In addition, four short push cores were taken in different depositional environments to assess the impact of early diagenesis and pore water chemistry on the U isotopic composition of bulk carbonates. We find that U concentrations are much higher in bulk carbonate sediments (avg. 4.1 ppm) than in primary precipitates (avg. 1.5 ppm). In almost all cases, the lowest bulk sediment U concentrations were as high as or higher than the highest concentrations found in primary precipitates. This is consistent with authigenic accumulation of reduced U(IV) during early diagenesis. The extent of this process appears sensitive to pore water H2S, and thus indirectly to organic matter content. d238/235U values were very close to seawater values in all of the primary precipitates, suggesting that these carbonate components could be used to reconstruct changes in seawater U geochemistry. However, d238/235U of bulk sediments from the push cores was 0.2-0.4 per mil heavier than seawater (and primary precipitates). These results indicate that authigenic accumulation of U under open-system sulfidic pore water conditions commonly found in carbonate sediments strongly affects the bulk U concentrations and 238U/235U ratios. We also report the occurrence of dolomite in a tidal pond core which contains low 234U/238U and 238U/235U ratios and discuss the possibility that the dolomitization process may result in sediments depleted in 238U. From this initial exploration, it is clear that 238U/235U variations in ancient carbonate sediments could be driven by changes in global average seawater, by spatial and temporal variations in the local deposition environment, or subsequent diagenesis. To cope with such effects, proxies for syndepositional pore water redox conditions (e.g., organic matter content, iron speciation, and trace metal distributions) and careful consideration of possible post-deposition alteration will be required to avoid spurious interpretation of 238U/235U data from ancient carbonate sediments.

Mineralogical and isotopic compositions of ODP Hole 107-650A

Red-brown dolomitic claystones overlay the Marsili Basin basaltic basement at ODP Site 650. Sequential leaching experiments reveal that most of the elements considered to have a hydrothermal or hydrogenous origin in a marine environment, such as Fe, Cu, Zn, Pb, Co, Ni, are present mainly in the aluminosilicate fraction of the dolomitic claystones. Their vertical distribution, content and partitioning chemistry of trace elements, and REE patterns suggest enhanced terrigenous input during dolomite formation, but no significant hydrothermal influence from the underlying basaltic basement. Positive correlations in the C and O isotopes in the dolomites reflect complex conditions during the dolomitization. The stable isotopes can be controlled in part by temperature variations during the dolomitization. Majority of the samples, however, form a trend that is steeper than expected for only temperature control on the C and O isotopes. The latter indicates possible isotopic heterogeneity in the proto-carbonate that can be related to arid climatic conditions during the formation of the basal dolomitic claystones. In addition, the dolostones stable isotopic characteristics can be influenced by diagenetic release of heavier delta18O from clay dehydration and/or alteration of siliciclastic material. Strontium and Pb isotopic data reveal that the non-carbonate fraction, the "dye" of the dolomitic claystones, is controlled by Saharan dust (75%-80%) and by material with isotopic characteristics similar to the Aeolian Arc volcanoes (20%-25%). The non-carbonate fraction of the calcareous ooze overlying the dolomitic claystones has a Sr and Pb isotopic composition identical to that of the dolomitic claystones, indicating that no change in the input sources to the sedimentary basin occurred during and after the dolomitization event. Combination of climato-tectonic factors most probably resulted in suitable conditions for dolomitization in the Marsili and the nearby Vavilov Basins. The basal dolomitic claystone sequence was formed at the initiation of the opening of the Marsili Basin (~2 Ma), which coincided with the consecutive glacial stage. The glaciation caused arid climate and enhanced evaporation that possibly contributed to the stable isotope variations in the proto-carbonate. The conductive cooling of the young lithosphere produced high heat flow in the region, causing low-temperature passive convection of pore waters in the basal calcareous sediment. We suggest that this pumping process was the major dolomitization mechanism since it is capable of driving large volumes of seawater (the source of Mg2+) through the sediment. The red-brown hue of the dolomitic claystones is terrigenous contribution of the glacially induced high eolian influx and was not hydrothermally derived from the underlying basaltic basement. The detailed geochemical investigation of the basal dolomitic sequence indicates that the dolomitization was most probably related to complex tectono-climatic conditions set by the initial opening stages of the Marsili Basin and glaciation.