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Zusammenfassung 13 Klone von Blaualgen verschiedener taxonomischer Stellung (Chroococcales, Chamaesiphonales, Nostocales) und verschiedener
?kologischer Gruppen (Plankter, Litoralformen, Aerophyten schattiger und sonniger Standorte), wurden mit Gamma-und UV-Strahlen
behandelt. Plankter erwiesen sich unabh?ngig von ihrer taxonomischen Stellung als wenig widerstandsf?hig: Die maximale Gammastrahlentoleranz
betrug je nach Klon 65 bis 260 krad bei Bestrahlungszeiten von rund 10 bis 40 Minuten, die maximale UV_Strahlentoleranz belief
sich (mit einer Ausnahme) unter unseren Versuchsbedingungen auf eine Bestrahlungszeit von 32 Minuten. Begleitbakterien tolerierten
durchwegs h?here Strahlendosen. Dagegen erwiesen sich Aerophyten bzw. Lithophyten von Standorten mit extremem natürlichem
Strahlungsklima auch im Experiment als sehr resistent. So überlebtenChamaesiphon polonicus undScytonema burmanicum siebenstündige Exposition in Gammastrahlen (totale Dosis 2500 krad) sowie vierstündige UV-Bestrahlung. Begleitbakterien überlebten
zwar die UV-Behandlung, nicht aber die hohen Gammastrahlendosen. Behandlung mit Gammastrahlen eignet sich daher zur Gewinnung
axenischer Kulturen von Cyanophyten extremer Naturstandorte.
Mehrere Monate alte axenische Kulturen vonScytonema burmanicum und vonS. lyngbyoides riechen übel, w?hrend bakterienhaltige Kulturen geruchlos bleiben. Vermutlich bauen die Begleitbakterien von den Algen ausgeschiedene,
übelriechende Stoffwechselprodukte zu geruchlosen Verbindungen ab.
Summary Thirteen strains of blue-green algae including members of the Chroococcales, Chamaesiphonales and Nostocales and belonging to various ecological groups have been exposed to various doses of gamma and UV radiation. Tolerances were independent of the taxonomic position but correlated with the ecological behaviour of the taxa involved. While planktonic species were quite sensitive to both UV and gamma radiation (maximum tolerance in the range of 65 to 260 krad) aerophytic and lithophytic species tolerated up to more than 2500 krad of gamma radiation and more than 4 hours of exposition to UV radiation. In cultures of planktonic species, gamma radiation killed the algae prior to the associated bacteria so that no axenic cultures could be obtained. In some cultures of aerophytic and lithophytic taxa however, bacteria were killed prior to the algae. Thus, axenic cultures of these strains could be obtained. Old axenic cultures ofScytonema burmanicum and ofS. lyngbyoides display a bad smell, whereas cultures with bacteria are odourless. Probably, the bacteria are reducing to odourless compounds the smelling substances excreted by the algae.
Résumé Treize souches cloniques de Cyanophycées d’eau douce appartenant aux ordres des Chroococcales, des Chamaesiphonales et des Nostocales et représentant divers types écologiques à savoir des formes du plancton et du littoral ainsi que des espèces saxicoles aériennes et subaériennes de habitats ombreux et fort ensoleillés ont été traité aux rayons et UV. Les espèces planctoniques se montraient peu résistantes, indépendemment de leur position taxonomique: Dans nos conditions, elles supportaient au maximum 32 minutes d’irradiation de rayons UV, et, selon la souche clonique, de 65 à 260 krad de rayons gamma. Les bactéries accompagnant les algues supportaient partout des doses d’irradiation plus élevées. Par contre, les espèces saxicoles provenant de stations aériennes ou subaériennes se montraient très résistantes.Chamaesiphon polonicus etScytonema burmanicum par exemple supportaient dans nos conditions une irradiation UV de 4 heures et une exposition aux rayons gamma de 6 heures (dose totale: 2500 krad). Les bactéries accompagnant ces espèces supportaient les rayons UV, mais non les rayons gamma. Le traitement avec des rayons gamma peut donc aboutir à des cultures axéniques de Cyanophycées d’habitats aériens ou subaériens. Les cultures axéniques deScytonema burmanicum et deS. lyngbyoides agées de quelques mois sentent mauvais, tandis que les cultures parallèles dont les algues sont accompagnées de bactéries restent sans odeur. Il semble que les bactéries décomposent les substances d’odeur désagréable produites par les deux espèces.相似文献
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Magdala Tesauro Christine Hollenstein Ramon Egli Alain Geiger Hans-Gert Kahle 《International Journal of Earth Sciences》2005,94(4):525-537
In order to study the ongoing tectonic deformation in the Rhine Graben area, we reconstruct the local crustal velocity and the strain rate field from GPS array solutions. Following the aim of this work, we compile the velocities of permanent GPS stations belonging to various networks (EUREF, AGNES, REGAL and RGP) in central western Europe. Moreover, the strain rate field is displayed in terms of principal axes and values, while the normal and the shear components of the strain tensor are calculated perpendicular and parallel to the strike of major faults. The results are compared with the fault plane solutions of earthquakes, which have occurred in this area. A broad-scale kinematic deformation model across the Rhine Graben is provided on the basis of tectonics and velocity results of the GPS permanent stations. The area of study is divided into four rigid blocks, between which there might be relative motions. The velocity and the strain rate fields are reconstructed along their borders, by estimating a uniform rotation for each block. The tectonic behaviour is well represented by the four-block model in the Rhine Graben area, while a more detailed model will be needed for a better reconstruction of the strain field in the Alpine region.
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Identifying slope processes over time and their imprint in soils of medium‐high mountains of Central Europe (the Karkonosze Mountains,Poland) 
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下载免费PDF全文 Jaroslaw Waroszewski Markus Egli Dagmar Brandová Marcus Christl Cezary Kabala Malgorzata Malkiewicz Jakub Kierczak Bartłomiej Glina Paweł Jezierski 《地球表面变化过程与地形》2018,43(6):1195-1212
Soils in mountainous areas are often polygenetic, developed in slope covers that relate to glacial and periglacial activities of the Pleistocene and Holocene and reflect climatic variations. Landscape development during the Holocene may have been influenced by erosion/solifluction that often started after the Holocene climatic optimum. To trace back soil evolution and its timing, we applied a multi‐methodological approach. This approach helped us to outline scenario of soil transformation. According to our results, some aeolian input must have occurred in the late Pleistocene. During that time and the early Holocene, the soils most likely had features of Cryosols or Leptosols. Physico‐chemical and mineralogical analyses have indicated that the material was denudated (between late Boreal to the Atlantic) from the ridge and upper‐slope positions forming a colluvium at mid‐slope positions. Later, during the Sub‐Boreal, mass wasting of the remains of silt material deposited at the end of the Pleistocene age on the ridge top seems to have occurred. In addition, the cool and moist conditions caused the deposition of a colluvium at the lower‐slope positions. The next phase was characterized by the transformation of Leptosols/Cambisols into Podzols at upper‐slope or shoulder positions and to Albic Cambisols at mid‐slope positions. During the Sub‐Boreal period, Stagnosols started to form at the lower part of the slope catena. Overall, the highest erosion rates were calculated at the upper‐slope position and the lowest rates at mid‐slope sites. Berylium‐10 (10Be) data showed that the Bs, BC/C were covered during the Holocene by a colluvium with a different geological composition which complicated the calculation of erosion or accumulation rates. The interpretation of erosion and accumulation rates in such multi‐layered materials may, therefore, be hampered. However, the multi‐methodological reconstruction we applied shed light on the soil and landscape evolution of the eastern Karkonosze Mountains. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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Alessandra Musso Michael E. Ketterer Konrad Greinwald Clemens Geitner Markus Egli 《地球表面变化过程与地形》2020,45(12):2824-2839
High mountainous areas are geomorphologically active environments which are strongly shaped by redistribution of sediments and soils. With the projected climate warming in the twenty-first century and the continued retreat of glaciers, the area of newly exposed, highly erodible sediments and soils will increase. This presents a need to better understand and quantify erosion processes in young mountainous soils, as an increase in erodibility could threaten human infrastructure (i.e. hydroelectric power, tourist installations and settlements). While soil development is increasingly well understood and quantified, a coupling to soil erosion rates is still missing. The aim of this study was, therefore, to assess how soil erosion rates change with surface age. We investigated two moraine chronosequences in the Swiss Alps: one in the siliceous periglacial area of Steingletscher (Sustenpass), with soils ranging from 30 a to 10 ka, and the other in the calcareous periglacial area of Griessgletscher (Klausenpass) with surfaces ranging from age of 110 a to 13.5 ka. We quantified the erosion rates using the 239+240Pu fallout radionuclides and compared them to physical and chemical soil properties and the vegetation coverage. We found no significant differences between the two parent materials. At both chronosequences, the erosion rates were highest in the young soils (on average 5−10 t ha-1 a-1 soil loss). Erosion rates decreased markedly after 3−5 ka of soil development (on average 1−2.5 t ha-1 a-1 soil loss) to reach a more or less stable situation after 10−14 ka (on average 0.3–2 t ha-1 a-1). Climate change not only causes glacier retreat, but also increased sediment dynamics. Depending on the relief and vegetational development, it takes up to at least 10 ka to reach soil stability. The establishment of a closed vegetation cover with dense root networks seems to be the controlling factor in the reduction of soil erodibility. © 2020 John Wiley & Sons, Ltd. 相似文献
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Nicholas Edkins Werner Schmutz Luca Egli Roger Davies Teruo Aoki Greg Mcfarquhar 《大气科学进展》2016,33(12):1325-1328
正1.Overview The 2016 International Radiation Symposium,a joint venture between the IRC(International Radiation Commission)and IAMAS(International Association of Meteorology and Atmospheric Sciences),took place at the University of Auckland from April 16th to 22nd.The wide scope of atmospheric radiation research was apparent,with focuses rang- 相似文献
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The spatio‐temporal distribution of snow in a catchment during ablation reflects changes in the total amount of snow water equivalent and is thus a key parameter for the estimation of melt water run‐off. This study explores possible rules behind the spatial variability of snow depth during the ablation season in a small Alpine catchment with complex topography. The snow depth observations are based on more than 160 000 terrestrial laser scanner data points with a spatial resolution of 1 m, which were obtained from 11 scanning campaigns of two consecutive ablation seasons. The analysis suggests that for estimating cumulative snow melt dynamics from the catchment investigated, assessing the initial snow distribution prior to the melt season is more important than addressing spatial differences in the melt behaviour. Snow volume and snow‐covered area could be predicted well using a conceptual melt model assuming spatially uniform melt rates. However, accurate results were only obtained if the model was initialized with a pre‐melt snow distribution that reflected measured mean and standard deviation. Using stratified melt rates on the other hand did not improve the model results. At least for sites with similar meteorological and topographical conditions, the model approach presented here comprises an efficient way to estimate snow depletion dynamics, especially if persistent snow accumulation pattern between years facilitate the characterization of the initial snow distribution prior to the melt. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Max Boxleitner Susan Ivy‐Ochs Markus Egli Dagmar Brandova Marcus Christl Dennis Dahms Max Maisch 《Boreas: An International Journal of Quaternary Research》2019,48(4):867-878
The Göschenertal (Göschenen valley) is the type locality of the so‐called Göschenen Cold Phases I (~3–2.3 ka) and II (~1.8–1.1 ka). According to earlier studies, these Late Holocene climatic cooling periods were characterized by changes in vegetation and pronounced glacier advances. As a peculiarity, the Göschenen Cold Phase I was thought to be connected to a local surge‐type advance of the Chelengletscher (Chelen glacier) – an exceptional event of unparalleled dimension in the European Alps. Based on cosmogenic 10Be exposure ages from moraine boulders, we investigated the local glacier chronology. In contrast to former research, moraines at different positions within the Göschenen valley (central Swiss Alps) have been dated to the Younger Dryas and the Early Holocene. This questions the applicability of palaeo‐Equilibrium Line Altitude (ELA) calculations for stadial attributions without additional numerical age constraints. Furthermore, we have found compelling evidence that the proposed non‐climatic glacier advance attributed to the Göschenen Cold Phase I did not occur. The present results, along with a reappraisal of the original study, question the scientific reliability and the glaciological definition of the Göschenen Cold Phases as glacier advances that clearly exceeded the Little Ice Age positions. While our data do not exclude potential changes in climate and vegetation, we nonetheless show that the Göschenen Cold Phases are not suitable as reference stadials in the system of Alpine Holocene glacier fluctuations. 相似文献
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Weathering, mineralogical evolution and soil organic matter along a Holocene soil toposequence developed on carbonate-rich materials 总被引：2，自引：0，他引：2
Markus Egli Christian Merkli Giacomo Sartori Aldo Mirabella Michael Pltze 《Geomorphology》2008,97(3-4):675-696
A toposequence of Holocene soils located between 1100–2400 m asl in the Italian Alps served as the basis for the following analyses: the weathering of limestone and dolomite, the calculation of mass balances, understanding the formation of pedogenic Fe and Al, the determination of soil mineral and clay mineral reactions and transformation and the measurement of accumulation and stabilisation mechanisms of soil organic matter. Leaching of carbonates is most intense at the lower elevations, although calcite and dolomite have a higher solubility at low temperatures. The pCO2 in the soil is higher at lower elevations and weathering is driven mainly by carbonic acids. At higher elevations, organic acids appear to determine the mineral transformations and weathering reactions to a greater extent. This suggests that two very different weathering regimes (carbonic and organic acid weathering) exist along the toposequence. The transformation of mica into vermiculite is the main process in both the clay and fine-earth fraction. Weathering of silicate minerals started even before the carbonates had been completely removed from the soils. The transformation mechanisms of silicate minerals in the A and O horizon at higher elevations was at least as intensive as that at the climatically warmer sites. The neoformation of pedogenetic clays at climatically cooler sites was slightly greater than that at the warmer sites. However, the formation rate of secondary Fe and Al phases was more pronounced at lower elevation, which means that this process seemed to be driven dominantly by carbonic acid (weathering of primary minerals). Soil organic matter (SOM) abundance in the mineral soil is nearly 15 kg/m2 at all sites and, surprisingly, no climate-driven effect could be detected. In general, the preservation and stabilisation of SOM was due to poorly crystalline Al and Fe phases and vermiculite, regardless of some variations in the composition of the parent material (varying calcite/dolomite ratio). 相似文献
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The role of climate and vegetation in weathering and clay mineral formation in late Quaternary soils of the Swiss and Italian Alps 总被引：2，自引：0，他引：2
Interactions between climate and soil remain ambiguous, particularly when silicate weathering and clay mineral formation and transformation rates are considered in relation to global climate changes. Recent studies suggest that climate affects weathering rates much less than previously thought. Here we show that the climate in the central European Alps has a significant, but indirect, influence on the weathering of soils through vegetation. The pattern of element leaching and mineral transformations is not only due to precipitation and temperature. Element leaching was greatest in subalpine forests near the timberline; weathering is lessened at higher and lower altitudes. Vegetation, therefore, contributes significantly to weathering processes. The highest accumulation of organic matter was found in climatically cooler sites (subalpine range) where the production of organic ligands, which enhance weathering, is greatest. Patterns of smectite formation and distribution had strong similarities to that of the elemental losses of Fe and Al (R = 0.69; P < 0.01) or base cations (R = 0.58; P < 0.05). Higher precipitation rates and the production of organic chelating compounds in the soil promoted the appearance of smectites. The relationship between climate, element leaching (Fe, Al, Ca, Mg, K, Na), and smectite formation is strongly nonlinear and driven by the podzolisation process, which is more pronounced near the timberline because of the bioclimatic constellation. Climate warming will probably, in the future, lead to a decrease in SOM stocks in the subalpine to alpine range because of more favourable conditions for biodegradation that would also affect weathering processes. 相似文献