Tab. 1: Age of biogene material from the ice margin, Kofoed-Hansen Bræ and Storstrømmen

Early Holocene recession of the ice cover over Germania Land in North-East Greenland 7.5 ka B.P. brought the Inland Ice margin back to a position close to the present. Continued recession after that time lead to the formation of a "Storstrømmen Sound" which separated Germania Land from mainland Greenland in the period from about 6 to 1 ka B.P. The present filling of the approximately 100 km long sound by the glaciers of Storstrømmen and Kofoed-Hansen Bræ must therefore have taken place during the Little lce Age. In an archaeological sense this implies deterioration of the living conditions of Neo-Eskimos compared to those of Palaeo-Eskimos. The neoglacial re-formation and present existence of the glaciers as a Little Ice Age relict may imply a present-day instability in their dynamics, as demonstrated by the pulsations (surge-like behaviour) in the last part of the 20th century. An earlier Little Ice Age advance might possibly have had the same amplitude as that documented from the 20th century but its exact age and character is not known. The glacio-isostatic response of the earth's crust to the variations in the Holocene glacier load implies a relatively slow and slight emergence and subsequent submergence. The shift from emergence to submergence must have taken place between about 2 and 1 ka B.P.

K-Ar age and chemical composition of volcanites from the Sea of Okhotsk

Volcanogenic rocks from the Sea of Okhotsk are divided into seven age complexes: Late Jurassic, Early Cretaceous, Late Cretaceous, Eocene, Late Oligocene, Late Miocene, and Pliocene-Pleistocene. All these complexes are united into two groups - Late Mesozoic and Cenozoic. Each group reflects a certain stage of development of the Sea of Okhotsk region. Late Mesozoic volcanites build the geological basement of the Sea of Okhotsk, and their petrochemical features are similar to those of the volcanic rocks from the Okhotsk-Chukotka Volcanogen. Pliocene-Pleistocene volcanites reflect stages of tectono-magmatic activity; the latter destroyed the continental margin and produced riftogenic troughs. Geochemical features of volcanites from the Sea of Okhotsk indicate influence of the sialic crust on magma formation and testify formation of the Okhotsk Sea Basin on the destructive margin of the Asian continent.

Table 1 : AMS-14C data used for the reconstruction of the Wismar Bay shoreline displacement curve

The Baltic coast of Mecklenburg-Vorpommern is located in the transition Zone between the region of Fennoscandian Uplift and the Central European Depression. In relation to the eustatic sea-level rise, the northeast coast shows a slower inundation, while for the southwestern area a faster transgression is indicated, which can be attributed to crustal movements. To determine the spatial and temporal differences since the onset of the Littorina Transgression, three relative sea-level curves have been established along a transect parallel to the gradient of upliftlsubsidence. The Wismar Bay area is one endpoint of the transect demonstrating today 10 Abb., 2 Tab. a relative sea-level rise of 1.4 mm/a. To determine the relative sea-level curve for the Wismar Bay, two sites were investigated on Rustwerder Spit (Poel) and Redentin. They provided reliable depth-age data, while the stratigraphy was additionally supported by lithological/geochemical, pollen, diatom and macrofossil data. Additional evidence was provided by archaeological submarine surveys and excavations. Comparing the new relative sea-level curve with a curve from the Vorpommern coast, it can be shown that for the period from 4000 cal BC until present, the differences between the two curves are caused by a constant neotectonic movement, while for the older periods an increasing isostatic component must be taken into account.

Air concentration of polybrominated diphenyl ethers around the Great Lakes and the Arctic

Atmospheric PBDEs were measured on a monthly basis in 2002-2004 at Point Petre, a rural site in the Great Lakes. Average air concentrations were 7.0 ± 13 pg/m**3 for the sum of 14BDE (excluding BDE-209), and 1.8 ± 1.5 pg/m**3 for BDE-209. Concentrations of 3 dominant congeners (i.e., BDE-47, 99, and 209) were comparable to previous measurements at remote/rural sites around the Great Lakes, but much lower than those at urban areas. Weak temperature dependence and strong linear correlations between relatively volatile congeners suggest importance of advective inputs of gaseous species. The significant correlation between BDE-209 and 183 implies their transport inputs associated with particles. Particle-bound percentages were found greater for highly brominated congeners than less brominated ones. These percentages increase with decreasing ambient temperatures. The observed gas/particle partitioning is consistent with laboratory measurements and fits well to the Junge-Pankow model. Using air mass back-trajectories, atmospheric transport to Point Petre was estimated as 76% for BDE-47, 67% for BDE-99, and 70% for BDE-209 from west-northwest and southwest directions. During the same time period, similar congener profiles and concentration levels were found at Alert in the Canadian High Arctic. Different inter-annual variations between Point Petre and Alert indicate that emissions from other regions than North America could also contribute PBDEs in the Arctic. In contrast to weak temperature effect at Point Petre, significant temperature dependence in the summertime implies volatilization emissions of PBDEs at Alert. Meanwhile, episodic observations in the wintertime were likely associated with enhanced inputs through long-range transport during the Arctic Haze period.

Geochemistry of volcanic rocks from the Hikurangi and Manihiki Plateaus

Here we present the first radiometric age data and a comprehensive geochemical data set (including major and trace element and Sr-Nd-Pb-Hf isotope ratios) for samples from the Hikurangi Plateau basement and seamounts on and adjacent to the plateau obtained during the R/V Sonne 168 cruise, in addition to age and geochemical data from DSDP Site 317 on the Manihiki Plateau. The 40Ar/39Ar age and geochemical data show that the Hikurangi basement lavas (118-96 Ma) have surprisingly similar major and trace element and isotopic characteristics to the Ontong Java Plateau lavas (ca. 120 and 90 Ma), primarily the Kwaimbaita-type composition, whereas the Manihiki DSDP Site 317 lavas (117 Ma) have similar compositions to the Singgalo lavas on the Ontong Java Plateau. Alkalic, incompatible-element-enriched seamount lavas (99-87 Ma and 67 Ma) on the Hikurangi Plateau and adjacent to it (Kiore Seamount), however, were derived from a distinct high time-integrated U/Pb (HIMU)-type mantle source. The seamount lavas are similar in composition to similar-aged alkalic volcanism on New Zealand, indicating a second wide-spread event from a distinct source beginning ca. 20 Ma after the plateau-forming event. Tholeiitic lavas from two Osbourn seamounts on the abyssal plain adjacent to the northeast Hikurangi Plateau margin have extremely depleted incompatible element compositions, but incompatible element characteristics similar to the Hikurangi and Ontong Java Plateau lavas and enriched isotopic compositions intermediate between normal mid-ocean-ridge basalt (N-MORB) and the plateau basement. These younger (~52 Ma) seamounts may have formed through remelting of mafic cumulate rocks associated with the plateau formation. The similarity in age and geochemistry of the Hikurangi, Ontong Java and Manihiki Plateaus suggest derivation from a common mantle source. We propose that the Greater Ontong Java Event, during which ?1% of the Earth's surface was covered with volcanism, resulted from a thermo-chemical superplume/dome that stalled at the transition zone, similar to but larger than the structure imaged presently beneath the South Pacific superswell. The later alkalic volcanism on the Hikurangi Plateau and the Zealandia micro-continent may have been part of a second large-scale volcanic event that may have also triggered the final breakup stage of Gondwana, which resulted in the separation of Zealandia fragments from West Antarctica.

Study on the last deglaciation section of sediment core GeoB6211-2

The North Atlantic Ocean underwent an abrupt temperature increase of 9 °C at high latitudes within a couple of decades during the transition from Heinrich event 1 (H1) to the Bølling warm event, but the mechanism responsible for this warming remains uncertain. Here we address this issue, presenting high-resolution last deglaciation planktic and benthic foraminiferal records of temperature and oxygen isotopic composition of seawater (d18OSW) for the subtropical South Atlantic. We identify a warming of ~6.5 °C and an increase in d18Osw of 1.2 per mil at the permanent thermocline during the transition, and a simultaneous warming of ~3.5 °C with no significant change in d18Osw at intermediate depths. Most of the warming can be explained by tilting the South Atlantic east-west isopycnals from a flattened toward a steepened position associated with a collapsed (H1) and strong (Bølling) Atlantic meridional overturning circulation (AMOC). However, this zonal seesaw explains an increase of just 0.3 per mil in permanent thermocline d18Osw. Considering that d18Osw at the South Atlantic permanent thermocline is strongly influenced by the inflow of salty Indian Ocean upper waters, we suggest that a strengthening in the Agulhas leakage took place at the transition from H1 to the Bølling, and was responsible for the change in d18Osw recorded in our site. Our records high-light the important role played by Indian-Atlantic interocean exchange as the trigger for the resumption of the AMOC and the Bølling warm event. of the AMOC and the Bølling warm event.

Radiocarbon age, and sedimentation and accumulation rate of core JM05-G001 obtained during Jan Mayen cruise JM050704 to the Barents Sea

Instrumental monitoring of the climate at high northern latitudes has documented the ongoing warming of the last few decades. Climate modelling has also demonstrated that the global warming signal will be amplified in the polar region. Such temperature increases would have important implications on the ecosystem and biota of the Barents Sea. This study therefore aims to reconstruct the climatic changes of the Barents Sea based on benthic foraminifera over approximately the last 1400 years at the decadal to sub-decadal scale. Oxygen and carbon isotope analysis and benthic foraminiferal species counts indicate an overall warming trend of approximately 2.6°C through the 1400-year record. In addition, the well-documented cooling period equating to the 'Little Ice Age' is evident between c. 1650 and 1850. Most notably, a series of highly fluctuating temperatures are observed over the last century. An increase of 1.5°C is shown across this period. Thus for the first time we are able to demonstrate that the recent Arctic warming is also reflected in the oceanic micro-fauna.

Particulate organic matter (POM) of samples from the Lena River delta

Particulate organic matter (POM) derived from permafrost soils and transported by the Lena River represents a quantitatively important terrestrial carbon pool exported to Laptev Sea sediments (next to POM derived from coastal erosion). Its fate in a future warming Arctic, i.e., its remobilization and remineralization after permafrost thawing as well as its transport pathways to and sequestration in marine sediments, is currently under debate. We present one of the first radiocarbon (14C) data sets for surface water POM within the Lena Delta sampled in the summers of 2009 - 2010 and spring 2011 (n = 30 samples). The bulk D14C values varied from -55 to -391 per mil translating into 14C ages of 395 to 3920 years BP. We further estimated the fraction of soil-derived POM to our samples based on (1) particulate organic carbon to particulate nitrogen ratios (POC : PN) and (2) on the stable carbon isotope (d13C) composition of our samples. Assuming that this phytoplankton POM has a modern 14C concentration, we inferred the 14C concentrations of the soil-derived POM fractions. The results ranged from -322 to -884 per mil (i.e., 3060 to 17 250 14C years BP) for the POC : PN-based scenario and from -261 to -944 per mil (i.e., 2370 to 23 100 14C years BP) for the d13C-based scenario. Despite the limitations of our approach, the estimated D14C values of the soil-derived POM fractions seem to reflect the heterogeneous 14C concentrations of the Lena River catchment soils covering a range from Holocene to Pleistocene ages better than the bulk POM D14C values. We further used a dual-carbon-isotope three-end-member mixing model to distinguish between POM contributions from Holocene soils and Pleistocene Ice Complex (IC) deposits to our soil-derived POM fraction. IC contributions are comparatively low (mean of 0.14) compared to Holocene soils (mean of 0.32) and riverine phytoplankton (mean of 0.55), which could be explained with the restricted spatial distribution of IC deposits within the Lena catchment. Based on our newly calculated soil-derived POM D14C values, we propose an isotopic range for the riverine soil-derived POM end member with D14C of -495 ± 153 per mil deduced from our d13C-based binary mixing model and d13C of -26.6 ± 1 per mil deduced from our data of Lena Delta soils and literature values. These estimates can help to improve the dual-carbon-isotope simulations used to quantify contributions from riverine soil POM, Pleistocene IC POM from coastal erosion, and marine POM in Siberian shelf sediments.

(Table 1) Biomass and total standing crop of major wet sedge tundra species at five sites at Alexandra Fiord in 1981 and 2005

The global climate is changing rapidly and Arctic regions are showing responses to recent warming. Responses of tundra ecosystems to climate change have been examined primarily through short-term experimental manipulations, with few studies of long-term ambient change. We investigated changes in above- and belowground biomass of wet sedge tundra to the warming climate of the Canadian High Arctic over the past 25 years. Aboveground standing crop was harvested from five sedge meadow sites and belowground biomass was sampled from one of the sites in the early 1980s and in 2005 using the same methods. Aboveground biomass was on average 158% greater in 2005 than in the early 1980s. The belowground biomass was also much greater in 2005: root biomass increased by 67% and rhizome biomass by 139% since the early 1980s. Dominant species from each functional group (graminoids, shrubs and forbs) showed significant increases in aboveground biomass. Responsive species included the dominant sedge species Carex aquatilis stans, C. membranacea, and Eriophorum angustifolium, as well as the dwarf shrub Salix arctica and the forb Polygonum viviparum. However, diversity measures were not different between the sample years. The greater biomass correlated strongly with increased annual and summer temperatures over the same time period, and was significantly greater than the annual variation in biomass measured in 1980-1983. Increased decomposition and mineralization rates, stimulated by warmer soils, were likely a major cause of the elevated productivity, as no differences in the mass of litter were found between sample periods. Our results are corroborated by published short-term experimental studies, conducted in other wet sedge tundra communities which link warming and fertilization with elevated decomposition, mineralization and tundra productivity. We believe that this is the first study to show responses in High Arctic wet sedge tundra to recent climate change.