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  • 1
    Electronic Resource
    Electronic Resource
    Determination of recent deposition rates in Lake Constance with radioisotopic methods (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 28 (1981), S. 0 
    Details
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Sedimentation rates were determined with the 210Pb method in eight sediment cores from Lake Constance. The rate of deposition in the main basin (Obersee) varies from about 0.06 g cm−2 y−1 in the central part to 0.13 g cm−2 y−1 in the eastern part of the lake and then increases rapidly towards the Rhine delta.In the central lake area the rate of deposition has been approximately constant since 1900, and dating with the 210Pb method is in good agreement with sedimentological observations. In the Konstanzer Trichter area, the deposition rate has been increasing since about 1955 as a result of eutrophication and subsequent high carbonate production.Dating with 137Cs is fairly accurate for sediments deposited at a high rate, but is questionable for slowly accumulating ones.A positive correlation of 210Pb fluxes and sedimentation rates indicates that 210Pb flux into sediments follows the distribution pattern of solids. 210Pb profiles in four sediment cores interpreted in terms of a constant flux model display synchronous fluctuations of the sedimentation rate; however, their relation to long-range particulate input variations remains to be proved.Sedimentation rates determined with the 210Pb method were used to calculate recent nutrient and heavy metal fluxes. Anthropogenic fluxes of Zn and Pb are in the same range of magnitude as in other polluted areas in Europe and America.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3091.1981.tb01927.x
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  • 2
    Electronic Resource
    Electronic Resource
    Introduction to the special issue (2004)
    Oxford, UK : Blackwell Science Pty
    Lakes & reservoirs 9 (2004), S. 0 
    Details
    ISSN: 1440-1770
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geography
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1770.2004.00237.x
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  • 3
    Electronic Resource
    Electronic Resource
    The impact of a sewage treatment plant's effluent on sediment quality in a small bay in Lake Geneva (Switzerland–France). Part 2: Temporal evolution of heavy metals (2004)
    Oxford, UK : Blackwell Science Pty
    Lakes & reservoirs 9 (2004), S. 0 
    Details
    ISSN: 1440-1770
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geography
    Notes: The Bay of Vidy is the most contaminated area of Lake Geneva, Switzerland, as a result of the release of treated and untreated waste water from the municipal sewage treatment plant of the city of Lausanne and its surroundings. The reconstruction of the historical deposition of heavy metals in the sediment of the bay has been performed by the analysis of several dated (radiocaesium) sediment cores. The presence of sewage-derived contaminants in the Bay of Vidy since the beginning of the sewage treatment plant's operations in 1964 is clearly observed, when a sharp increase in heavy metal contents is recorded, with maximum concentrations of cadmium, copper, zinc and lead occurring between the late 1960s and early 1970s. Despite considerable improvement in recent times, the present concentrations of the investigated heavy metals in sediments of the Bay of Vidy are still higher than concentrations measured at the centre of the lake, the latter close to Lake Geneva's natural background values. It is concluded that the quantity of heavy metals deposited in the bay is considerable and, because of sediment instability, will constitute a potential hazard for biota.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1770.2004.00234.x
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  • 4
    Electronic Resource
    Electronic Resource
    River, reservoir and lake sediment contamination by heavy metals downstream from urban areas of Switzerland (2004)
    Oxford, UK : Blackwell Science Pty
    Lakes & reservoirs 9 (2004), S. 0 
    Details
    ISSN: 1440-1770
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geography
    Notes: This paper quantifies sediment contamination by heavy metals in four reservoirs and one lake located downstream from major urban areas in Switzerland. The waterbodies include the Wettingen Reservoir (located on the Limmat River downstream from Zürich), the Klingnau Reservoir (on the lower Aare River), the Wohlen Reservoir (downstream from Berne), the Verbois Reservoir (downstream from Geneva) and Vidy Bay (Lake Geneva, city of Lausanne). For all sediment cores and contaminants, a trend is observed from high contaminant values in the lower part of the cores, decreasing to lower concentrations in the upper part of the cores. However, for each site and each element, specific features are recognized. Applying the criteria of the Swiss ordinance on soil protection, all sediment cores must be classified as contaminated by one or more contaminants and at variable levels. From these data, it is concluded that: reservoirs and lakes located downstream from major urban centres in Switzerland have accumulated significant volumes of contaminated sediments in the past, representing the largest, but not the most intensely, contaminated sites on a national scale; the main environmental risk is remobilization of the contaminants and their return to the food chain, particularly by infiltration into the groundwater; and although the processes of remobilization are identified, the conditions of occurrence and the amplitude of the processes are still poorly known. Different options of reservoir and lake sediment management also are discussed and further research topics defined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1770.2004.00236.x
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  • 5
    Electronic Resource
    Electronic Resource
    Identification of stoichiometric iron-phosphorus colloids produced in a eutrophic lake (1999)
    Springer
    Aquatic sciences 61 (1999), S. 133-149 
    Details
    ISSN: 1420-9055
    Keywords: Key words: Aquatic colloids, iron, phosphorus, stoichiometric composition, nutrient scavenging, electron microscopy.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract: Iron-rich colloids formed at the oxic-anoxic interface of a eutrophic lake (Lake Lugano; CH) were characterized by bulk chemical methods and analytical electron microscopy. Fractionation of raw waters showed that non-dissolved iron is particulate above the oxicline and mainly colloidal in the anoxic part of the hypolimnion, while non-dissolved ortho-phosphate is mostly colloidal through the water column. Because of these differences, filtration did not prove helpful for the determination of the role of iron-rich species in the scavenging of ortho-phosphate. On the other hand, analytical electron microscopy revealed that iron-rich nano-granules (ca. 50nm) are associated to the surface of bacterially produced fibrillar polysaccharides. Iron colloids in these complex entities contain important and constant amounts of phosphorus ([PO4]part:[Fe]part = 0.48 ± 0.11, n = 1096 Fe-rich entities analyzed by electron microscopy), which suggests that phosphates are stoichiometrically incorporated into the hydrous iron oxide phase, with a tentative composition Fe2[OOH]1-x[(OH)3]x[PO4], during its genesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000270050058
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  • 6
    Electronic Resource
    Electronic Resource
    Evolution of the Upper Rhone River discharge and suspended sediment load during the last 80 years and some implications for Lake Geneva (2000)
    Springer
    Aquatic sciences 62 (2000), S. 54-67 
    Details
    ISSN: 1420-9055
    Keywords: Key words: Sediment rating curve, sediment load, dam, deep water lake.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract: During this century, the characteristics of the Upper Rhone River discharge, flowing into Lake Geneva, have been altered in response to the changes which have occurred in its watershed. Principally, numerous hydroelectric dams have been constructed on the course of the Rhone River tributaries. At present the major reservoirs can hold about 1220106m3 of water, which represents 1/5 of the total annual Rhone River flow. Flow regime characteristics of the river have been modified by the dam operations. Water is released from reservoirs during winter and stored in summer. Large floods have also been reduced in amplitude and frequency. From the available literature data, sediment rating curves have been calculated and used to estimate the evolution of the sediment load from the Rhone River to Lake Geneva. They show that sediment input has decreased by at least a factor 2. This reduction has impacted the occurrence of underflows along the lake bottom, due to the reduction of sediment-laden floods, which in turn may have considerable negative effects on the reoxygenation of Lake Geneva deep waters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000270050075
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  • 7
    Electronic Resource
    Electronic Resource
    The influence of late Quaternary stagnations on clay sedimentation in the eastern Mediterranean sea (1979)
    Springer
    International journal of earth sciences 68 (1979), S. 302-317 
    Details
    ISSN: 1437-3262
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Abstract Late Quaternary sapropels of the eastern Mediterranean differ from normal sediments in their clay mineral composition. Clay minerals in the sapropels studied here are only slightly affected, or are not affected at all by diagenetic alteration. This permits the observation of primary differences. During stagnation periods, the contribution of remote or accessory sources was reduced or even absent. Different circulation patterns and, particularly, a general decline in deeper water currents activity might be held responsible for the observed differences in the clay mineral composition of sapropels and normal sediments.
    Abstract: Résumé Les sapropels quaternaires de la Méditerranée orientale se distinguent des vases communes par la composition des minéraux argileux. Les argiles des sapropels examinés sont peu affectés par l'altération diagénétique, ce qui permet l'observation de différences primaires. On a conclu, que pendant les périodes de stagnation, la contribution des argiles provenant des sources éloignées ou secondaires, a été réduite ou même interrompue. Différentes conditions de circulation et, avant tout, la réduction d'activité des courants profonds, sont probablement responsables des différences observées dans la composition des minéraux argilezx des sapropels et des vases communes.
    Notes: Zusammenfassung Die quartären Sapropele des östlichen Mittelmeeres unterscheiden sich von den normal marinen Sedimenten in ihrer Tonmineralzusammensetzung. Die hier untersuchten Tone der Sapropele zeigen nur geringe oder gar keine diagenetischen Veränderungen. Diese Tatsache erlaubt, Rückschlüsse auf primäre Unterschiede zu ziehen. Während der Stagnationsperioden war die Zufuhr von Tonen aus entfernten oder weniger wichtigen Liefergebieten stark vermindert. Unterschiedliche Zirkulation, besonders eine geringere Aktivität der Tiefenströmungen, scheinen die Ursache für die beobachteten Unterschiede in der Tonmineralzusammensetzung zwischen Sapropel- und normal-marinen Sedimenten
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01821133
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  • 8
    Electronic Resource
    Electronic Resource
    Radioisotopic evidence of perturbations of recent sedimentary record in lakes: a word of caution for climate studies (1992)
    Springer
    Climate dynamics 6 (1992), S. 145-152 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The rate of climatic change estimated from the gradient of signals recorded in lake sediments may be erroneous if post-depositional perturbations are overlooked. A smear out of a pulse signal, over a variable thickness of core section, due to physical or biological mixing, is a well known phenomena. Much less attention is paid to a possible overestimation of the rate of change when a part of record is missing due to an erosion event. In this paper we show a few examples of recent lake sediment perturbations and the resulting distortions in the time scale, as documented by short-lived radionuclides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193526
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