Pedogeomorphology, geochronology and paleobotany of soil profiles obtained in the Kyichu River catchment, sourthern Tibet

Results of pedogeomorphological, geochronological and paleobotanical investigations are presented covering the last ca. 4,000 years. The study sites are located in the heavily degraded Kyichu River catchment around Lhasa at 3,600-4,600 m a.s.l. Repeatedly, colluvial sediments have been recorded overlying paleosols. These deposits can be divided into i) coarse-grained sediments with a high proportion of stones and boulders originating from alluvial fans and debris flows, ii) matrix supported sediments with some stones and boulders originating from mudflows or combined colluvial processes such as hillwash plus rock fall, and iii) fine-grained sediments originating from hill wash. The IRSL multi-level dating of profile QUG 1 points to a short-time colluvial sedimentation between 1.0 ± 0.1 and 0.8 ± 0.1 ka. In contrast, dated paleosols of profile GAR 1 (7,908 ± 99 and 3,668 ± 57 BP) encompass a first colluvial episode. Here, the upper colluvial sedimentation took place during several periods between 2.6 ± 0.3 and 0.4 ± 0.1 ka. For the first time in Tibet, a systematic extraction, determination and dating of charcoals from buried paleosols was conducted. The charcoals confirm the Late Holocene presence of juniper forests or woodlands in a now treeless, barren environment. A pollen diagram from Lhasa shows a distinct decline of pollen of the Jumperus-type around 4,140 ± 50 BP, which is interpreted as indicating a clearing of forests on the adjacent slopes. It is assumed that the environmental changes from forests to desertic rangelands since ca. 4,000 BP have been at least reinforced by humans.

Manganese contents and accumulation rates in reduced bottom sediments of the Sea of Okhotsk

Manganese contents in reduced sediments and accumulation rates were investigated. Their values in sediments of most of cores are background (0.03-0.07 %).Anomalous concentrations (up to 2.5 %) and accumulation rates (up to 60 mg/cm**2/ka) occur near the known region of hydrothermal barite mineralization in the Derugin Basin. High accumulation rates of Mn (>10 mg/cm**2/ka) also occur in Holocene sediments to south-east from the Derugin Basin. It can be assumed that high Mn contents and accumulation rates occur there due to transportation of Mn-rich water from the Derugin Basin in the near-bottom layer under the lower border of the Sea of Okhotsk Intermediate Water. Intensive Mn accumulation is also typical for the South Okhotsk Basin near the Bussol Strait. Mn accumulation rates of glacial sediments of the second oxygen isotope stage are less significant, which is presumed to be caused by paleoceanological reasons.

Changes in bottom water corrosiveness and carbonate ion concentrations in the sub-Antarctic Atlantic during the last glacial period

The glacial climate system transitioned rapidly between cold (stadial) and warm (interstadial) conditions in the Northern Hemisphere. This variability, referred to as Dansgaard-Oeschger variability, is widely believed to arise from perturbations of the Atlantic Meridional Overturning Circulation. Evidence for such changes during the longer Heinrich stadials has been identified, but direct evidence for overturning circulation changes during Dansgaard-Oeschger events has proven elusive. Here we reconstruct bottom water [CO3]2- variability from B/Ca ratios of benthic foraminifera and indicators of sedimentary dissolution, and use these reconstructions to infer the flow of northern-sourced deep water to the deep central sub-Antarctic Atlantic Ocean. We find that nearly every Dansgaard-Oeschger interstadial is accompanied by a rapid incursion of North Atlantic Deep Water into the deep South Atlantic. Based on these results and transient climate model simulations, we conclude that North Atlantic stadial-interstadial climate variability was associated with significant Atlantic overturning circulation changes that were rapidly transmitted across the Atlantic. However, by demonstrating the persistent role of Atlantic overturning circulation changes in past abrupt climate variability, our reconstructions of carbonate chemistry further indicate that the carbon cycle response to abrupt climate change was not a simple function of North Atlantic overturning.

Lignin, phenols, and some chemical elements in aerosols and bottom sediments from the Tropical North Atlantic

A study of composition of biomarkers (lignin and phenols) in aerosols and bottom sediments from the Tropical North Atlantic was carried out. It was shown that organic matter of aerosols was mostly composed of products of terrestrial plants (arboreal fibers, pollen, and spores). Biomarker composition in the aerosols and in the bottom sediments was practically similar, which proved delivery of terrigenous organic matter to the ocean via the atmosphere.

Composition of bottom sediments and their exchange with seawater in the Amur and Zolotoy Rog bays, Sea of Japan

Transition of Zn, Cu, Cd, and Pb into solution is studied for experimental suspensions of coastal marine sediments with different degrees of pollution from the Amur Bay (Sea of Japan) over 30-70 days. Concentrations of dissolved metals were measured by a voltammetry method. Transition of Zn and Cd into solution was shown to be linearly dependent on initial pollution of sediments with these metals. Cadmium mobilization is due to gradual degradation of organic matter from sediments. Under degradation processes Zn quickly goes into solution during sedimentation and from silts, while in case of polluted sediments it is slowly mobilized during oxidation of sulfides. Behavior of Cu is complex because of binding of mobilized metal by dissolved organic compounds. Transition of lead into solution is negligible. Calculation of potential transition of metals from sediments into water on the basis of experimental data and its comparison with downward sedimentary flux showed that in the studied area secondary pollution of water by aerobic degradation of sediments is possible only for Cd.

Hydrology dataset based on 111 CTD stations in the North Aegean Sea during June 1998 from the project INTERREGAEGEAN

The combination of two research projects offered us the opportunity to perform a comprehensive study of the seasonal evolution of the hydrological structure and the circulation of the North Aegean Sea, at the northern extremes of the eastern Mediterranean. The combination of brackish water inflow from the Dardanelles and the sea-bottom relief dictate the significant differences between the North and South Aegean water columns. The relatively warm and highly saline South Aegean waters enter the North Aegean through the dominant cyclonic circulation of the basin. In the North Aegean, three layers of distinct water masses of very different properties are observed: The 20-50 m thick surface layer is occupied mainly by Black Sea Water, modified on its way through the Bosphorus, the Sea of Marmara and the Dardanelles. Below the surface layer there is warm and highly saline water originating in the South Aegean and the Levantine, extending down to 350-400 m depth. Below this layer, the deeper-than-400 m basins of the North Aegean contain locally formed, very dense water with different i/S characteristics at each subbasin. The circulation is characterised by a series of permanent, semi-permanent and transient mesoscale features, overlaid on the general slow cyclonic circulation of the Aegean. The mesoscale activity, while not necessarily important in enhancing isopycnal mixing in the region, in combination with the very high stratification of the upper layers, however, increases the residence time of the water of the upper layers in the general area of the North Aegean. As a result, water having out-flowed from the Black Sea in the winter, forms a separate distinct layer in the region in spring (lying between "younger" BSW and the Levantine origin water), and is still traceable in the water column in late summer.

Results of biological and geological bottom investigations carried out during Cruise 43 of R/V Akademik Kurchatov in the South Atlantic

The book is devoted to investigations of benthic fauna and geology of the Southern Atlantic Ocean. These works have been carried out in terms of exploring biological structure of the ocean and are of great importance for development of this fundamental problem. They are based on material collected during Cruise 43 of R/V Akademik Kurchatov in 1985-1986 and Cruise 43 of R/V Dmitry Mendeleev in 1989. Problems of quantitative distribution, group composition and trophic structure of benthos in the Southern Scotia Sea, along the east-west Transatlantic section along 31°30'S, and offshore Namibia in the area of the Benguela upwelling are under consideration in the book. Authors present new data on fauna of several groups of deep-sea bottom animals and their zoogeography. Much attention is paid to analysis of morphological structure of the Scotia Sea floor considered in terms of plate tectonics. Bottom sediments along the Transatlantic section and facial variation of sediments in the area of South Shetland Islands and of the continental margin of Namibia are under consideration.