ALBERT

Description: Sediment sequences retrieved from two coring sites at the Lake Novoe (Point N1 (60° 48.984´ N; 34° 57.718´W, depth – 2.7 m.); point N2 (60° 49.265´ N; 34° 57.451´ W, depth – 3.07 m), North-Eastern part of Podporozhsky district, Leningrad region, northwestern Russia, were analyzed for pollen analysis. Studied community passed through 5 stages in its development. Age control was calibrated by comparison of our pollen data to ones described in literature related to the same region (Onega Lake surroundings). Pollen data from ten cores were taken for this purpose. Birch woodlands, probably thinly-planted were widespread in Preborial stage (10 200-9300 years ago), then distinct change towards to warmer and more humid climatic conditions took place, open Pinus–Betula forest around the lake were gradually replaced by boreal forest with Picea, Pinus, Betula, Alnus incana and Corylus. This type of communities continued to dominate till the end of Boreal period (8000 years ago). The Atlantic period (8000 - 4600 years ago) was marked by increased abundance of broad-leaved species and thermiphyllic herbs. Quercus, Ulmus, Tilia and Corylus appeared in the area simultaneously. At the end of the Atlantic period broad-leafed woods began being replaced by spruce and pine-tree communities. Later, during the Subboreal (4600-2500 years ago), these processes continued. Subatlantic period (started 2500 years ago) marked by development of Pine woods with birch and willow. Coasts of the lake probably were covered with grasslands formed by Poaceae, Cyperaceae, and Asteraceae. Modern stage of community was studied by means of phytosocialogical descriptions along 4 km transect. Besides, pollen traps were set every 200 m through this transect. Nowadays forests of Piceeta-Pineta formation prevail within 70% of territory, 30% of it are covered by secondary wood communities with Betula, Alnus and Salix. Specter of trapped pollen reflected composition of plant communities satisfactory, with a value of 4.9 for grasslands and 7.7 (maximal – 9.1) in forests and shown the mean value about 5.7±2.3 which is of satisfactory correction.

Description: The Quaternary history of the Arctic Ocean constitutes from alternating glacial, deglacial and interglacial/interstadial periods on the Arctic mainland. A precise knowledge of the past rates and scales of climate change might give an idea about the climate variability and give a possibility to predict future climate changes. The high-resolution records may help to reconstruct the paleoenvironmental conditions and solve some uncertainties in the debate of recent climate change (Stein, 2008 and reference therein). This study was focused on sediment core PS72/413-3 from the Northern transect across the Mendeleev Ridge. This short sediment core was taken using the giant box corer (GKG) during the Polarstern Expedition ARKXXIII/3 in 2008. Different sedimentary proxies such as geochemistry (total organic carbon, inorganic carbon, carbon to nitrogen ratio), lithology (Stein et al., 2009), micropaleontology (absolute abundances of benthic and planktonic foraminifers, planktonic to benthic foraminifera relation, absolute and relative abundances of C. wuellerstorfi and B. aculeata), grain size composition, tentative X-ray diffraction and colour reflectance measurements were used for the core investigation. The age model of the core was established by the correlation to the age model developed by Jang et al. (2013) for the adjacent sediment core at site PS72/410. The lithofacies were determined based on Stein et al. (2010b) and colour reflectance measurements. According to established stratigraphic framework the PS72/413-3 comprises marine isotope stages (MIS) 5a to 1. The proxy results were discussed in terms of depositional environments and paleoenvironmental conditions. The alternation of brown and grey beds down the sediment core was clearly to identify. Brown beds (B1-B3) are supposed to be deposited in the interglacial/interstadial environment with a diminished sea-ice cover and high primary production. The deposition environment of the grey beds (G1-G3) is interpreted as deglacial and/or glacial termination periods with minimum foraminiferal abundances and iceberg-dominated sediment transport. The so called condensed sections were defined based on lithology and proxy correlation with the neighbor-core PS72/410 (Jang et al., 2013) and most likely coincide with glacial environment with a completely packed sea-ice cover. The characteristic for central Arctic Ocean sediments pink-white layers W3 and PW were defined on bases of G1 and B3 beds respectively based on Stein et al. (2010b), inorganic carbon content and X-ray diffraction measurements. The obtained data were discussed using the published data (Adler et al., 2009; Backman et al., 2004; Darby et al., 2006; Jang et al., 2013; Nørgaard-Pedersen et al., 1998, 2003; Polyak et al., 2004, 2009; Poore et al., 1999; Stein et al., 1994). In general our results are in an agreement with an interpretation of MIS 1, 3, 5a as an interglacial/interstadial and MIS 2 and 4 as glacial periods. In frame of this study the origin of the inorganic carbon peak within MIS 5a and the paleoecology in terms of foraminiferal abundances were discussed. Based on the proposed age model the sedimentation rates were calculated and they range from 0.1 cm/ky to 2.5 cm/ky during the glacial and interglacial/interstadial periods respectively with an average value of 0.84 cm/ky. That is in agreement with the proposed mean sedimentation rates for the northern Mendeleev Ridge of 0.5-0.9 cm/ky (Stein et al., 2010b).

Description: A pronounced intra-interglacial MIS 11 cold event was revealed in the North Atlantic by sea surface temperature (SST) and salinity (SSS) reconstructions. SSTs were established using TEX86-indices derived from relative abundances of glycerol dialkyl glycerol tetraethers (GDGTs) of Thaumarcheota and alkenone-based Uk’37 indices. To assess variations in palaeo-SSS, the hydrogen isotopic (δD) compositions of long chain alkenones were determined. For further interpretation, the obtained SST and SSS reconstructions were compared to relative planktic foraminiferal abundances, ice rafted debris (IRD) counts and δ18O records from benthic and planktic foraminifera. According to our data, the temperature amplitude of the aforementioned cold event reached 7 °C. We assume that this value might combine the actual cooling with an additional effect of a vertical migration of the Thaumarchaeota to deeper and, therefore, colder water layers, which might occur due to an enhanced intensity of open ocean upwelling which is generally characteristic for this location during cooling episodes. This explanation is also supported by changes in stable oxygen isotopes of deep-living planktic foraminiferal species G. truncatulinoides (s) and (d). A pronounced increase of δ18O values contemporaneous with the cold event might indicate a change of habitat conditions of these species towards colder temperatures. Another evidence of enhanced upwelling intensity during this episode might be derived from increased relative abundance of planktic foraminiferal species G. bulloides, whose geographical distribution is related to upwelling zones. A salinity drop was registered before the SST decrease. Because the intra-interglacial MIS 11 cold event occurred during the phase of slowly decreasing benthic δ18O values, we assume that it might be related to the late phase of the circum-North Atlantic ice sheet decay. Therefore, its nature might resemble the one of the 8.2 ka Holocene event.

Description: Recent observations of enhanced oceanic heat transfer into the Arctic concomitant with the rapid sea-ice decrease temptingly suggest a direct relationship between both features. However, except for marginal areas of the Arctic Ocean where warm and saline Atlantic Water (AW) reaches the surface, the majority of AW heat is presently isolated from the sea-ice cover by a cold and fresh halocline layer. No evidence has been found to suggest a weakening of the halocline across the central Arctic basins that would enhance the AW heat transfer to the surface. A more direct link between sea-ice reduction and AW inflow is, however, seen in the inflowing Barents Sea branch in both historical and observational time series. In this presentation the AW advection into the Arctic Ocean and its influence on sea-ice variability will be reviewed from a geological point of view. Records from the geologic past are of great value as the time span of modern observations and historical data is often too short to comprehend long-term trends and causes of AW variability, changes in the marginal ice zone, and the vertical structure of the Arctic water column. Paleoceanographic studies from the recent interglacial indirectly suggest that the strength of AW advection and its propagation into the Arctic interior is effective in melting sea ice in combination with other factors such as insolation, sea level, freshwater input, and upper water mass stratification. However, to date, very little paleoceanographic work in the Arctic has focused on how the strength and position of the halocline has changed during previous interglacial periods. More direct reconstructions of the Arctic’s vertical stratification in the geologic past are needed to provide a longer-term view on the stability of the halocline, and more generally, the role of Atlantic Water inflow on the stability of sea ice in the interior basins.

Description: Marine carbonates are widely used archives for paleoceanographic and climatic reconstructions. The cold-water carbonates investigated in this study are skeletal remains of the two cold-water coral (CWC) species Lophelia pertusa and Madrepora oculata. These framework-building scleractinian coral species are widespread on the continental slopes of the world’s oceans and their aragonitic skeletons can be precisely dated with radiometric techniques, which makes them an interesting archive. In the northeast Atlantic CWCs are known to build different ecosystems. While reefs in Norway, mound structures off the coast of Ireland and CWC occurrences in the Gulf of Cadiz are relatively well studied, comparably little is known about the Bay of Biscay, a region that connects the eastern temperate Atlantic with the more northern regions. In order to examine the CWC distribution and its history in the Bay of Biscay, this study analyzes coral samples from six sediment cores that were retrieved during METEOR Cruise M84/5 in June 2011 along a depth transect (539mbsl - 980mbsl) in the St. Nazaire canyon in the northern Bay of Biscay. In this setting CWCs currently occur in patches and thickets and not in large reefs like they are e.g. known from the Norwegian coast. The aim of tthis study is to examine the CWC growth in the St. Nazaire canyon, determine how long CWCs have been growing in this setting and reconstruct under which environmental conditions they lived. For this purpose the coral samples were mechanically and chemically cleaned, dated via the U/Th-decay chain and analyzed for their skeletal stable isotope and element ratios. The measurement of these ratios was carried out on a Quadrupole Inductively Coupled Plasma Mass Spectrometer (Q ICP-MS). The dating of the samples revealed coral ages from 12,5 kyBP to present-day ages. This shows that since the end of the last glacial the St. Nazaire canyon represented a suitable setting for CWC growth. While other CWC ecosystems further south, e.g. in the Gulf of Cadiz, seem to have thrived only during glacial times, the dated coral samples of this study indicate, that the St. Nazaire canyon rather belongs to the CWC ecosystems that flourish during interglacial times like in regions further north. Moreover, the dating of the coral samples documents numerous inversions in the sediment cores that complicate the reconstruction of the deposition history, but at the same time emphasize the special geological character of the canyon setting. Given the time frame, some of the measured element ratios could be used as proxies to reconstruct environmental parameters that characterized the CWC ecosystem in former times: Paleotemperature reconstruction, based on a Mg/Li-proxy calibrated for L. pertusa, showed that seawater temperatures throughout the Holocene were in the range of ~9-10°C. Similarly stable were the pH-conditions during the Holocene. The pH-values were reconstructed by applying a U/Ca-proxy that has only recently been defined and so far has not been used for fossil corals. The pH-values during the last 12,5 ky fluctuated slightly (±0,2) around the modern pH-value of 8. In contrast to pH and temperature, coral Ba/Ca ratios, interpreted as an indicator for paleoproductivity, showed an almost linear decrease of around 40%. The underlying reasons could include changes in the current regime and/or changes in the surface productivity, probably triggered by decreasing terrigenous input. This could be one of the factors, why current CWC growth only occurs relatively sparsely. Physical and geochemical boundary conditions of CWC growth are a topic of ongoing research. The reconstructed environmental parameters are important factors, but only in the context with other parameters like current velocities and sedimentation rates that influence and constrain CWC distribution too. Hence, along with others, the reconstructed factors temperature, pH and nutrient supply seem to create a generally favorable setting for CWC growth in the St. Nazaire canyon since ~12,5 kyBP.

Description: The region of North-West of China is faced with different ecological problems, such as land degradation (mainly due to lack of water resources), desertification and water scarcity. The only reliable source of water supply for the arid low lands in the HeiHe river Basin is the water resources in the high elevation areas of the Qilian Mountains. Low land’s irrigation agriculture and urban water supply depend on the steadiness of water yield from the non-perennial tributaries in the source regions in the Qilian Mountains. To investigate the steadiness conditions and to stabilize the water yield from the Southern Qilian Mountains, German-Chinese project of “Long-term optimization of water yield from the Qilian Mountains to the HeiHe River basin by an integrated development of water protection forests and land-use” in province of Gansu have been started. Current Master Thesis research was accomplished in the frames this project. The task for the research was to perform fine resolution land-use map for the Southern Qiliqn Mountains and Middle Hexi corridor, which didn’t exist before. To implement the task of distant analysis of vegetation patterns Geographic Information Systems have been used. Multispectral image from Landsat-7 satellite, Thematic Mapper (TM ) and Enhanced Thematic Mapper Plus (ETM+) have been used with NDVI overlay and Shuttle Radar Topography Mission (SRTM) sensor (to produced DEM) as the additional data layers to implement multi-source land cover classification using a well-known Maximum Likelihood Classification (MLC) method. Free Open source SAGA GIS software was chosen to fulfill the task. Classification and interpretation of different landscape patterns, based on ecological and geomorphologic indicators from satellite imaginary data and intensive field investigations were performed. Based on it and supported with field ground-check GPS survey, Classification Map was developed. Also NDVI layer values were analyzed and show the changes in vegetation cover during the last 3 decades. The results of the work are important for further mapping assessment and high resolution Classification map processing, as well as for the purpose of hydrological modeling and meteorological downscaling in the Project research. Understanding of the current status, classification and spatial distribution of degraded land is very important issue all over the word and for the regional development of in the Heihe river basin in particular.

Description: Auf dem stark verkarsteten, nahezu vegetationslosen Zugspitzplatt im Wettersteingebirge (Nördliche Kalkalpen) gibt es in 2290 m Höhe eine Doline mit einer fast 1 m mächtigen Füllung aus lössähnlichem Feinsediment. Dieser Feinstaub enthält Pollen und Sporen in Mengen, die trotz der Lage des Untersuchungspunktes weit oberhalb der heutigen Waldgrenze ohne weitere Anreicherung für Pollenanalysen ausreichten. Trotz schlechter Pollenerhaltung konnten die basalen Schichten dieses Profils pollenanalytisch datiert werden. Das älteste Sediment wurde während des frühen Atlantikums, zur Zeit des thermischen Optimums des Holozäns, abgelagert. Eine AMS-Datierung bestätigt dies (7415 ± 30 BP). Seitdem wurde der Untersuchungspunkt nicht mehr von einem Gletscher überfahren. Der gut belegte Gletschervorstoss der Löbben-Schwankung (sog. Plattstand, zwischen 3400 und 3100 Jahren BP) hat die Doline gerade nicht mehr erreicht. Die bekannten holozänen Gletscherstände sind in einer Übersicht dargestellt. Die Zusammensetzung der Pollenspektren der beiden ältesten Proben und deren sehr hohe Pollenkonzentrationen erlauben den Schluss, dass die Entfernung der Doline zum Wald während des Atlantikums sehr viel geringer war als derzeit.

Description: Auf dem stark verkarsteten, nahezu vegetationslosen Zugspitzplatt im Wettersteingebirge (Nördliche Kalkalpen) gibt es in 2290 m Höhe eine Doline mit einer fast 1 m mächtigen Füllung aus lössähnlichem Feinsediment. Dieser Feinstaub enthält Pollen und Sporen in Mengen, die trotz der Lage des Untersuchungspunktes weit oberhalb der heutigen Waldgrenze ohne weitere Anreicherung für Pollenanalysen ausreichten. Trotz schlechter Pollenerhaltung konnten die basalen Schichten dieses Profils pollenanalytisch datiert werden. Das älteste Sediment wurde während des frühen Atlantikums, zur Zeit des thermischen Optimums des Holozäns, abgelagert. Eine AMS-Datierung bestätigt dies (7415 ± 30 BP). Seitdem wurde der Untersuchungspunkt nicht mehr von einem Gletscher überfahren. Der gut belegte Gletschervorstoss der Löbben-Schwankung (sog. Plattstand, zwischen 3400 und 3100 Jahren BP) hat die Doline gerade nicht mehr erreicht. Die bekannten holozänen Gletscherstände sind in einer Übersicht dargestellt. Die Zusammensetzung der Pollenspektren der beiden ältesten Proben und deren sehr hohe Pollenkonzentrationen erlauben den Schluss, dass die Entfernung der Doline zum Wald während des Atlantikums sehr viel geringer war als derzeit.

Description: research