39 research outputs found

    Remote-sensing-based analysis of landscape change in the desiccated seabed of the Aral Sea-a potential tool for assessing the hazard degree of dust and salt storms

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    With the recession of the Aral Sea in Central Asia, once the world's fourth largest lake, a huge new saline desert emerged which is nowadays called the Aralkum. Saline soils in the Aralkum are a major source for dust and salt storms in the region. The aim of this study was to analyze the spatio-temporal land cover change dynamics in the Aralkum and discuss potential implications for the recent and future dust and salt storm activity in the region. MODIS satellite time series were classified from 2000-2008 and change of land cover was quantified. The Aral Sea desiccation accelerated between 2004 and 2008. The area of sandy surfaces and salt soils, which bear the greatest dust and salt storm generation potential increased by more than 36 %. In parts of the Aralkum desalinization of soils was found to take place within 4-8 years. The implication of the ongoing regression of the Aral Sea is that the expansion of saline surfaces will continue. Knowing the spatio-temporal dynamics of both the location and the surface characteristics of the source areas for dust and salt storms allows drawing conclusions about the potential hazard degree of the dust load. The remote-sensing-based land cover assessment presented in this study could be coupled with existing knowledge on the location of source areas for an early estimation of trends in shifting dust composition. Opportunities, limits, and requirements of satellite-based land cover classification and change detection in the Aralkum are discussed

    Late Pleistocene (MIS2) environmental changes and palaeoclimatic dynamics around Aiding Lake in the Turpan Basin, Xinjiang Province, NW-China

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    A 12 m sediment core from the Aiding Lake basin in the today hyper-arid Turpan depression (Autonomous Xinjiang Province, NW-China) has been studied. The core, which was drilled near the deepest point of the endorheic Turpan basin (154 m below sea level), revealed several climatic and palaeoenvironmental changes during the Late Pleistocene. The sediments which were analyzed relating to sedimentology (grain size), geochemistry (Ti/Al ratio, chemical index of weathering, total organic and inorganic carbon, sulfur, nitrogen), and magnetic susceptibility, are of fluvial, eolian, and lacustrine origin. Age control was done by five C-14 dates. Reservoir effects for the stratigraphic units were considered. Less saline conditions lasted until the end of the Pleistocene, forced by stronger westerlieS and low, but increasing temperatures. Sometime after Dansgaard-Oeschger event 1 (14.6 ka) up to present, environmental conditions were arid and Aiding became a salt lake. High sand contents indicate eolian input during a period of cold, windy and arid conditions, associated with Heinrich event 2 (-24.8-23.4 ka cal BP; HEMMING 2004), whereas high sand input of the uppermost 2 m and salt accumulation reflects a general change to drier conditions since the Pleistocene/Holocene transition. In summary, the Lake decreased from its maximum size of around 3000 km(2) during the MIS3 to a seasonal small lake today. The measured Rb/Sr ratio, generally used as an indicator for weathering conditions of lake catchments, with reduced Sr influx during arid periods due to weak chemical weathering, has to be interpreted differently for Aiding Lake: Very low Rb/Sr ratios in the uppermost 2.7m similar to that of unweathered loess represent the recent drought and Sr accumulation during the Holocene. Contrary to other studies, we found e.g. that Rb/Sr dynamics do not indicate the intensity of past chemical weathering, but allows the distinction of different source areas and the decoupling of weathering and subsequent transport to the sink. This is consistent to the westerly index, according to AN et al. (2012), which was calculated to separate eolian from fluvial influx. Our study shows that the interpretation of palaeoclimate proxies depends on the understanding of the entire process-response-system within a specific catchment and environment. In summary and in comparison to other regional studies, we can distinguish six palaeoclimatic phases: A) with strong westerlies and cold-wet climate (c. 28.5-24.8 ka BP); B) with very strong winter monsoon and very cold climate (24.8-23.4 ka BP); C) with strong winter monsoon and cold climate, merging to cold more humid conditions due to enhancing westerlies (23.4 - similar to 20.5 ka BP). Phase D showed strongly reduced eolian dynamics afterwards and was a period of cool-wet conditions with weakening westerlies and a geomorphological stability in the Turpan basin (until similar to 16 ka). Phase E was dominated by the cold-dry spell of Heinrich event 1(15.8-14.6 ka BP), eolian transport was reactivated by high winter monsoon wind speeds, and fluvial discharge decreased. During the D/O1 warming (after 14.6 ka BP), material was merely transported from the melting mountain glaciers to the lake. In the Turpan basin, warm and dry conditions led to a sealing of surfaces by biocrusts, which again suppressed eolian processes. Phase F started with the transition to hot-very dry Holocene climate. It experienced enhanced seasonality (stronger winter and summer monsoon) and marks a period when the propagation of moist westerly air masses to the Turpan basin was prevented

    AN OPEN SCIENCE APPROACH TO GIS-BASED PALEOENVIRONMENT DATA

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    Paleoenvironmental studies and according information (data) are abundantly published and available in the scientific record. However, GIS-based paleoenvironmental information and datasets are comparably rare. Here, we present an Open Science approach for creating GIS-based data and maps of paleoenvironments, and Open Access publishing them in a web based Spatial Data Infrastructure (SDI), for access by the archaeology and paleoenvironment communities. We introduce an approach to gather and create GIS datasets from published non-GIS based facts and information (data), such as analogous maps, textual information or figures in scientific publications. These collected and created geo-datasets and maps are then published, including a Digital Object Identifier (DOI) to facilitate scholarly reuse and citation of the data, in a web based Open Access Research Data Management Infrastructure. The geo-datasets are additionally published in an Open Geospatial Consortium (OGC) standards compliant SDI, and available for GIS integration via OGC Open Web Services (OWS)

    AN OPEN SCIENCE APPROACH TO GIS-BASED PALEOENVIRONMENT DATA

    No full text
    Paleoenvironmental studies and according information (data) are abundantly published and available in the scientific record. However, GIS-based paleoenvironmental information and datasets are comparably rare. Here, we present an Open Science approach for creating GIS-based data and maps of paleoenvironments, and Open Access publishing them in a web based Spatial Data Infrastructure (SDI), for access by the archaeology and paleoenvironment communities. We introduce an approach to gather and create GIS datasets from published non-GIS based facts and information (data), such as analogous maps, textual information or figures in scientific publications. These collected and created geo-datasets and maps are then published, including a Digital Object Identifier (DOI) to facilitate scholarly reuse and citation of the data, in a web based Open Access Research Data Management Infrastructure. The geo-datasets are additionally published in an Open Geospatial Consortium (OGC) standards compliant SDI, and available for GIS integration via OGC Open Web Services (OWS)

    Geoarchaeological site documentation and analysis of 3D data derived by terrestrial laser scanning

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    Terrestrial laser scanning was conducted to document and analyse sites of geoarchaeological interest in Jordan, Egypt and Spain. In those cases, the terrestrial laser scanner LMS-Z420i from Riegl was used in combination with an accurate RTK-GPS for georeferencing of the point clouds. Additionally, local surveying networks were integrated by established transformations and used for indirect registration purposes. All data were integrated in a workflow that involves different software and according results. The derived data were used for the documentation of the sites by accurate plans and cross-sections. Furthermore, the 3D data were analysed for geoarchaeological research problems, such as volumetric determinations, the ceiling thickness of a cave and lighting simulations based on path tracing. The method was reliable in harsh environmental conditions, but the weight of the instrument, the measuring time and the minimum measurement distance were a drawback. However, generally an accurate documentation of the sites was possible. Overall, the integration in a 3D GIS is easily possible by the accurate georeference of the derived data. In addition, local survey results are also implemented by the established transformations. Enhanced analyses based on the derived 3D data shows promising results

    Long-term survival of a HCC-patient with severe liver dysfunction treated with sorafenib

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    Hepatocellular carcinoma (HCC) is the most common primary cancer of the liver. Prognosis and treatment options are stage dependent. In general, prognosis of patients with unresectable HCC is poor, especially for those patients with impaired liver function. Whereas treatment with the novel molecular tyrosine kinase inhibitor sorafenib (Nexavar) was shown to result in prolonged survival in patients with preserved liver function, its’ possible application in HCC-patients with strongly impaired liver function has not been clearly assessed. Here, we report on a 47-year-old male patient who presented with Child-Pugh class C liver cirrhosis and multifocal, non-resectable HCC. The patient was treated for 27 mo with Sorafenib, which was not associated with major drug-related side effects. During treatment, a reduction in tumour size of 24% was achieved, as assessed by regular CT scan. Moreover, within the 27 mo interval of stable tumour disease, liver function improved from Child-Pugh class C to class A
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