Distribution of clay minerals in surface sediments of the Eurasian Arctic Ocean

Clay-mineral distributions in the Arctic Ocean and the adjacent Eurasian shelf areas are discussed to identify source areas and transport pathways of terrigenous material in the Arctic Ocean. The main clay minerals in Eurasian Arctic Ocean sediments are illite and chlorite. Smectite and kaolinite occur in minor amounts in these sediments, but show strong variations in the shelf areas. These two minerals are therefore reliable in reconstructions of source areas of sediments from the Eurasian Arctic. The Kara Sea and the western part of the Laptev Sea are enriched in smectite, with highest values of up to 70% in the deltas of the Ob and Yenisey rivers. Illite is the dominant clay mineral in all the investigated sediments except for parts of the Kara Sea. The highest concentrations with more than 70% illite occur in the East Siberian Sea and around Svalbard. Chlorite represents the clay mineral with lowest concentration changes in the Eastern Arctic, ranging between 10 and 25%. The main source areas for kaolinite in the Eurasian Arctic are Mesozoic sedimentary rocks on Franz-Josef Land islands. Based on clay-mineral data, transport of the clay fraction via sea ice is of minor importance for the modern sedimentary budget in the Arctic basins.

Polyaromatic hydrocarbons in sediments from the Barents and White Seas

Polycyclic aromatic hydrocarbons (PAHs) are common environmental contaminants which can be derived from anthropogenic sources, such as combustion and discharges from extraction and transport, and natural processes, including leakage and erosion of fossil carbon. Natural PAH sources contribute, along with biological activities and terrestrial run-off, to the organic carbon content in sediments.The Barents Sea region is far from many anthropogenic sources of PAH, but production and trans-shipment of hydrocarbons is increasing. We present data for polycyclic aromatic hydrocarbon (PAH) concentrations in bottom sediments from 510 stations in the Barents and White Seas, and along the northern coast of Norway.

Accumulation of particulate organic carbon at the Eurasian continental margin during late Quaternary times

Data on the amount and composition of organic carbon were determined in sediment cores from the Kara and Laptev Sea continental margin, representing oxygen isotope stages 1-6. The characterization of organic matter is based on hydrogen index (HI) values, n-alkanes and maceral composition, indicating the predominance of terrigenous organic matter through space and time. The variations in the amount and composition of organic carbon are mainly influenced by changes in fluvial sediment supply, Atlantic water inflow, and continental ice sheets. During oxygen isotope stage (OIS) 6, high organic carbon contents in sediments from the Laptev Sea and western East Siberian Sea continental margin were probably caused by the increased glacial erosion and further transport in the eastward-flowing boundary current along the continental margin. During OIS 5 and early OIS 3, some increased amounts of marine organic matter were preserved in sediments east of the Lomonosov Ridge, suggesting an influence of nutrient-rich Pacific waters. During OIS 2, terrigenous organic carbon supply was increased along the Barents and western Kara Sea continental margin caused by extended continental ice sheets in the Barents Sea (Svalbard to Franz Josef Land) area and increased glacial erosion. Along the Laptev Sea continental margin, on the other hand, the supply of terrigenous (organic) matter was significantly reduced due to the lack of major ice sheets and reduced river discharge. Towards the Holocene, the amount of total organic carbon (TOC) increased along the Kara and Laptev Sea continental margin, reaching average values of up to 0.5 g C/cm**2/ky. Between about 8 and 10 ka (9 and 11 Cal ka), i.e., during times when the inner shallow Kara and Laptev seas became largely flooded for the first time after the Last Glacial Maximum, maximum supply of terrigenous organic carbon occurred, which is related to an increase in coastal erosion and Siberian river discharge. During the last 8000 years, the increased amount of marine organic carbon preserved in the sediments from the Kara and Laptev Sea continental margin is interpreted as a result of the intensification of Atlantic water inflow along the Eurasian continental margin.

Analysis of minerals from Arctic Ocean sediments

The Arctic Ocean System is a key player regarding the climatic changes of Earth. Its highly sensitive ice Cover, the exchange of surface and deep water masses with the global ocean and the coupling with the atmosphere interact directly with global climatic changes. The output of cold, polar water and sea ice influences the production of deep water in the North Atlantic and controls the global ocean circulation ("the conveyor belt"). The Arctic Ocean is surrounded by the large Northern Hemisphere ice sheets which not only affect the sedimentation in the Arctic Ocean but also are supposed to induce the Course of glacials and interglacials. Terrigenous sediment delivered from the ice sheets by icebergs and meltwater as well as through sea ice are major components of Arctic Ocean sediments. Hence, the terrigenous content of Arctic Ocean sediments is an outstanding archive to investigate changes in the paleoenvironment. Glazigenic sediments of the Canadian Arctic Archipelago and surface samples of the Arctic Ocean and the Siberian shelf regions were investigated by means of x-ray diffraction of the bulk fraction. The source regions of distinct mineral compositions were to be deciphered. Regarding the complex circumpolar geology stable christalline shield rocks, active and ancient fold belts including magmatic and metamorphic rocks, sedimentary rocks and wide periglacial lowlands with permafrost provide a complete range of possible mineral combinations. Non- glaciated shelf regions mix the local input from a possible point source of a particular mineral combination with the whole shelf material and function as a sampler of the entire region draining to the shelf. To take this into account, a literature research was performed. Descriptions of outcropping lithologies and Arctic Ocean sediments were scanned for their mineral association. The analyses of glazigenic and shelf sediments yielded a close relationship between their mineral composition and the adjacent source region. The most striking difference between the circumpolar source regions is the extensive outcrop of carbonate rocks in the vicinity of the Canadian Arctic Archipelago and in N Greenland while siliciclastic sediments dominate the Siberian shelves. In the Siberian shelf region the eastern Kara Sea and the western Laptev Sea form a destinct region defined by high smectite, (clino-) pyroxene and plagioclase input. The source of this signal are the extensive outcrops of the Siberian trap basalt in the Putorana Plateau which is drained by the tributaries of the Yenissei and Khatanga. The eastern Laptev Sea and the East Siberian Sea can also be treated as one source region containing a feldspar, quartz, illite, mica, and chlorite asscciation combined with the trace minerals hornblende and epidote. Franz Josef Land provides a mineral composition rich in quartz and kaolinite. The diverse rock suite of the Svalbard archipelago distributes specific mineral compositions of highly metamorphic christalline rocks, dolomite-rich carbonate rocks and sedimentary rocks with a higher diagenetic potential manifested in stable newly built diagenetic minerals and high organic maturity. To reconstruct the last 30,000 years as an example of the transition between glacial and interglacial conditions a profile of sediment cores, recovered during the RV Polarstern" expedition ARK-VIIIl3 (ARCTIC '91), and additional sediment cores around Svalbard were investigated. Besides the mineralogy of different grain size fractions several additional sedimentological and organo-geochemical Parameterswere used. A detailed stratigraphic framework was achieved. By exploiting this data set changes in the mineral composition of the Eurasian Basin sediments can be related to climatic changes. Certain mineral compositions can even be associated with particular transport processes, e.g. the smectitel pyroxene association with sea ice transport from the eastern Kara Sea and the western Laptev Sea. Hence, it is possible to decipher the complex interplay between the influx of warm Atlantic waters into the Southwest of the Eurasian Basin, the waxing and waning of the Svalbard1Barents- Sea- and Kara-Sea-Ice-Sheets, the flooding of the Siberian shelf regions and the surface and deep water circulation. Until now the Arctic Ocean was assumed to be a rather stable System during the last 30,000 years which only switched from a completely ice covered situation during the glacial to seasonally Open waters during the interglacial. But this work using mineral assemblages of sediment cores in the vicinity of Svalbard revealed fast changes in the inflow of warm Atlantic water with the Westspitsbergen Current (< 1000 years), short periods of advances and retreats of the marine based Eurasian ice sheets (1000-3000 years), and short melting phases (400 years?). Deglaciation of the marine-based Eurasian and the land-based north American and Greenland ice sheets are not simultaneous. This thesis postulates that the Kara Sea Ice Sheet released an early meltwater signal prior to 15,000 14C years leading the Barents Sea Ice Sheet while the western land-based ice sheets are following later than 13,500 14C years. The northern Eurasian Basin records the shift between iceberg and sea-ice material derived from the Canadian Arctic Archipelago and N-Greenland and material transported by sea-ice and surface currents from the Siberian shelf region. The phasing of the deglaciation becomes very obvious using the dolomite and quartd phyllosilicate record. It is also supposed that the flooding of the Laptev Sea during the Holocene is manifested in a stepwise increase of sediment input at the Lomonosov Ridge between the Eurasian and Amerasian Basin. Depending on the strength of meltwater pulses from the adjacent ice sheets the Transpolar Drift can probably be relocated. These movements are traceable by the distribution of indicator minerals. Based on the outcome of this work the feasibility of bulk mineral determination can be qualified as excellent tool for paleoenvironmental reconstructions in the Arctic Ocean. The easy preparation and objective determination of bulk mineralogy provided by the QUAX software bears the potential to use this analyses as basic measuring method preceding more time consuming and highly specialised mineralogical investigations (e.g. clay mineralogy, heavy mineral determination).

Data compilation on the biological response to ocean acidification: environmental and experimental context of data sets and related literature

The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.

Heavy mineral investigations from surface sediments of the East Greenland continental margin

During the expeditions ARK-VII/1, ARK-VII/3 and ARK-Xl2 sediment cores were taken by "RV Polarstern" from the shelf and the fjords of East Greenland and the Greenland Sea. The magnetic susceptibility and heavy mineral were determined at 48 surface sediment samples from undisturbed box cores. The main objective of this study was the identification of source areas and transport processes of terrigenous sediments at the East Greenland continental margin. The results can be summarized as lollows: 1a) Magnetic susceptibility in the North Atlantic is useful to detect delivery regions of the material transported by currents. b) The magnetic susceptibility is controlled by the ferromagnetic particles of the silt fraction. c) There are four important source areas: . The ferromagnetic particles of the box core PS2644-2 are transported from the Iceland Archipelago. . The material from the Geiki-Plateau effects the magnetic susceptibility in the Scoresby Sund Basin. . The magnetic susceptibility in the shelf regions in the North are produced by material from the fjords. . The ferromagnetic particles in the Greenland Sea are derived from the Mid Atlantic Ridges in the east. d) It is possible to determine the rock type, which delivers the ferromagnetic material because of differences in magnetic susceptibility of different intensity. . The erosion of the basalts of the Geiki-Plateau and the basalts of the Mid Atlantic ridges produce the high magnetic susceptibility in the south. . The magnetic susceptibility on the shelf in the north are probably produced by erosionproducts of the gneises of East Greenland. (2a) Heavy mineral assemblages show a significant difference between material transported by the Transpolar Drift from the Eurasian shelf regions (amphiboles, clinopyroxene, orthopyroxene) and material derived from East Greenland (garnets and opaque minerals). Transport via ice is dominant. b) lt is also possible to show different petrographic provenances (volcanic and metamorphic provenances). These associations verify the source areas. c) The information of heavy mineral composition gives no more detailed hint on the rock type or rock formation in the source area, due to mixing processes, large area of investigation and the sample quantity.

Epibenthic foraminiferal d13C in the Recent deep Arctic Ocean

Low planktic and benthic d18O and d13C values in sediments from the Nordic seas of cold stadials of the last glaciation have been attributed to brines, formed similar to modern ones in the Arctic Ocean. To expand on the carbon isotopes of this hypothesis I investigated benthic d13C from the modern Arctic Ocean. I show that mean d13C values of live epibenthic foraminifera from the deep Arctic basins are higher than mean d13C values of upper slope epibenthic foraminifera. This agrees with mean high d13C values of dissolved inorganic carbon (DIC) in Arctic Bottom Water (ABW), which are higher than mean d13CDIC values from shallower water masses of mainly Atlantic origin. However, adjustments for oceanic 13C-Suess depletion raise subsurface and intermediate water d13CDIC values over ABW d13CDIC ones. Accordingly, during preindustrial Holocene times, the d13CDIC of ABW was as high or higher than today, but lower than the d13CDIC of younger subsurface and intermediate water. If brine-enriched water significantly ventilated ABW, brines should have had high d13CDIC values. Analogously, high-d13CDIC brines may have been formed in the Nordic seas during warm interstadials. During cold stadials, when most of the Arctic Ocean was perennially sea-ice covered, a cessation of high-d13CDIC brine rejection may have lowered d13CDIC values of ABW, and ultimately the d13CDIC in Nordic seas intermediate and deep water. So, in contrast to the idea of enhanced brine formation during cold stadials, the results of this investigation imply that a cessation of brine rejection would be more likely.

Magnetic susceptibility and ice-rafted debris in surface sediments of the Nordic Sea

Magnetic susceptibility and ice-rafted debris of surface sediments in the Nordic Seas were investigated to reconstruct source areas and recent transport pathways of magnetic minerals. From the distribution of magnetic susceptibility and ice-rafted debris and published data on petrographic tracers for iceberg drift, we reconstructed a counter-clockwise iceberg drift pattern during cooler phases in the Holocene, which is similar to conceptual and numerical models for Weichselian iceberg drift. The release of basaltic debris at Scoresby Sund played a significant role for the magnetic signature of stadial/interstadial events during isotope stage 3 recorded in sediment cores of the Nordic Seas.

Seawater carbonate chemistry and biological processes during experiments with spider crab Hyas araneus, 2009

Future scenarios for the oceans project combined developments of CO2 accumulation and global warming and their impact on marine ecosystems. The synergistic impact of both factors was addressed by studying the effect of elevated CO2 concentrations on thermal tolerance of the cold-eurythermal spider crab Hyas araneus from the population around Helgoland. Here ambient temperatures characterize the southernmost distribution limit of this species. Animals were exposed to present day normocapnia (380 ppm CO2), CO2 levels expected towards 2100 (710 ppm) and beyond (3000 ppm). Heart rate and haemolymph PO2 (PeO2) were measured during progressive short term cooling from 10 to 0°C and during warming from 10 to 25°C. An increase of PeO2 occurred during cooling, the highest values being reached at 0°C under all three CO2 levels. Heart rate increased during warming until a critical temperature (Tc) was reached. The putative Tc under normocapnia was presumably >25°C, from where it fell to 23.5°C under 710 ppm and then 21.1°C under 3000 ppm. At the same time, thermal sensitivity, as seen in the Q10 values of heart rate, rose with increasing CO2concentration in the warmth. Our results suggest a narrowing of the thermal window of Hyas araneus under moderate increases in CO2 levels by exacerbation of the heat or cold induced oxygen and capacity limitation of thermal tolerance.