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  • 1
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An Energy-dispersive Miniprobe Multielement Analyzer (EMMA) was designed and constructed for sensitive, rapid, and non-destructive analysis of trace elements (As, Cr, Cu, Fe, Ga, Ge, Hf, Mn, Ni, Pb, Rb, Se, Sr, Th, Y, U, Zn) in small (e.g. 50 μm) samples such as individual mineral grains from rocks. An alternative configuration of the EMMA instrument is described here for use with larger samples such as powders of coal, soil, sediments, and plant materials. To minimize heterogeneity problems, a larger X-ray beam size (0.1 × 6 mm) was used by installing a different collimator, and the sample holder rotated 25 times per minute. Using this approach, Rb, Sr, Cu, Zn and Pb were measured in peat samples collected from bogs in Switzerland and northern Scotland. The detection limit for Pb, for example, is approximately 0.3 μg/g which is one order of magnitude better than conventional XRF analyzers. For comparison, Pb was also measured in acid digests of the same samples using GFAAS. The Pb results obtained using EMMA are comparable to the GFAAS data for the continental peat samples. However, in the Cl-rich samples from the maritime bogs, the GFAAS signal was strongly suppressed, and an accurate comparison of the two methods was not possible. The EMMA technique, therefore, has three advantages over conventional GFAAS: first, no sample dissolution is required; second, several elements of interest are determined simultaneously; and third, the EMMA technique is not subject to matrix interferences.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Peat cores were taken from two contrasting Sphagnum bogs in the Jura Mountains of Switzerland. At Etang de la Gruyere (EGr), 6.5 m of peat has accumulated during the past 10,000 years. In the first 100 cm of this profile there are several distinct peaks in ash content, but the values are well within the range for typical ombrotrophic Sphagnum bogs. There is also considerable variation in the concentrations of major and trace lithogenic metals (Al, Ti, Sc, Ca, Mg, Rb, and Sr), but most of this is simply a reflection of the natural variations in the amount of mineral matter in the peats. The Ca/Mg molar ratios in the peats at EGr are comparable to or lower than the average rainwater composition in this area, showing that this section of the peat core is ombrotrophic (i.e. rainwater-fed). In other words, the inorganic constituents in the surface peats at EGr were supplied exclusively by atmospheric deposition. This peat core, therefore, is suitable for studying the historical record of atmospheric metal deposition. Arsenic, Cu, Pb, Sb, and Zn are all more abundant in surface and near surface peat layers compared to deeper parts of the profile. Enrichment factors (EFs) for the profile were calculated conservatively by normalizing the metal/Sc ratios of individual peat samples to the average of the five lowest metal/Sc ratios in this part of the core (69–84 cm); these are tentatively assumed to represent pre-Industrial background values. The maximum EFs are approximately 5 times for Cu, 15 times for As, and 30 to 50 times for Pb, Sb, and Zn. At La Tourbière des Genevez (TGe), 1.5 m of peat represents 4,800 years of peat formation. At this site, the ash contents are higher and increase progressively with depth to values which are characteristic of minerotrophic fen peats. The concentration profiles of Al, Ti, Sc, Ca, Mg, Rb, Sr show the same general trend. The Ca/Mg molar ratios of these peats are generally twice the rainwater average, showing that this bog is essentially minerotrophic (ie groundwater-fed). Thus, the inorganic cccstituents in these peats were provided by both atmospheric and hydrospheric processes. Despite this, the Cu, Pb, Sb, and Zn concentrations are generally very similar to those at EGr, especially in the uppermost part of the profile, indicating that recent atmospheric inputs also dominate the supply of these metals to this bog. However, the minimum Pb and Sb concentrations in this profile are approximately five times higher than the corresponding values at EGr. The minerotrophic profile at TGT, therefore, could not by itself be used to calculate rates of atmospheric Pb and Sb deposition because it is impossible to distinguish between atmospheric and hydrospheric metal inputs. At TGe, As concentrations increase continuously with depth, reaching concentrations in the deeper, older peats which are more than 50 times higher than the ‘background’ As values at EGr. At this site the natural supply of As by mineral soil water completely masks the recent, elevated inputs contributed by atmospheric deposition. Thus, the peat core from TGe is also unsuitable for studying atmospheric As deposition.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 86 (1999), S. 262-275 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 4
    Publication Date: 2009-10-01
    Description: Background, aim, and scopeFluorescence and UV-visible spectroscopies are simple but useful methods to characterize organic matter in the aqueous phase according to its aromatic nature and humification degree. Although there are several studies about porewater and water-extractable organic matter (WEOM) from peat, at present, no comparative investigations are available in the literature. Thus, the aim of the present study was to identify and compare chemical and spectroscopic features of porewaters and corresponding WEOM samples along a 105-cm undisturbed peat profile.Material and methodsThe peat core was collected in June 2005 from a Swiss ombrotrophic bog and divided into slices of 1 ± 0.15-cm thickness. Porewater samples ( n  = 91) were extracted and analyzed for pH; from these, 30 samples were filtered (0.45 μm), analyzed for dissolved organic carbon (DOC) concentration, and characterized by means of UV-vis (E4/E6 ratio) and fluorescence spectroscopies. The same analyses were also carried out on the WEOM of the corresponding peat samples.Results and conclusionsThe results show several differences between porewaters and WEOM throughout the bog profile. In particular, and with the exception of the first ca. 20 cm depth, spectroscopic data clearly underline a more “humic-like” character of DOC of WEOM compared to porewater samples. Furthermore, the trends in E4/E6 ratios of both porewaters and WEOM samples indicate that the organic matter is characterized by decreasing aromaticity, molecular weights, and degree of polycondensation throughout the profile. The high correlation among the bulk density of the peat and the DOC concentrations in both porewaters and WEOM samples demonstrates a clear stratification of the organic matter which suggests that the vertical migration of DOC is rather limited. The first ca. 20 cm of the profile shows also opposite physicochemical and spectroscopic features compared to the deeper horizons probably because this is the predominantly oxic zone with far greater physiological activity of plants and microorganisms.Recommendations and perspectivesAssessing porewater and WEOM features throughout peat, soil, and sediment profiles is important to better understand water–sediment interface dynamics and translocation processes of organic and inorganic pollutants, especially considering that ombrotrophic bogs are often used as archives of atmospheric depositions. ©2009 Springer-Verlag
    Print ISSN: 1439-0108
    Electronic ISSN: 1614-7480
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
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  • 5
    Publication Date: 1999-06-08
    Print ISSN: 0028-1042
    Electronic ISSN: 1432-1904
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
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  • 6
    Publication Date: 2003-10-01
    Description: A 9000cal. year record of geochemistry was analysed in a sediment core obtained from a Swiss alpine hard-water lake (1937 ma.s.l.) that is located at the present-day tree-line. Geochemical stratigraphies are compared to changes in mineralogy, grain-size, pollen, and macrofossil records. This allows the reconstruction of the effects of changes in vegetation and of 3500 years of land-use in the catchment area on sediment geochemistry. Using principal component analysis, two major geochemical groups are distinguished: (i) Changes in concentrations of Rb, Ti, Zr, Fe, As, and Pb are closely related to corresponding changes in the concentrations of quartz and clay. They are thus considered to represent the silicate fraction which shows an increase from the oldest to the youngest core section. (ii) In contrast, Ca and Sr concentrations are positively correlated with changes in silt, sand, and calcite. They are therefore considered to represent the carbonate fraction which gradually decreased. Based on constrained cluster analysis, the core is divided into two major zones. The oldest zone (A; 9000–6400 cal.BP) is characterised by high concentrations of detrital carbonates. The more open catchment vegetation at that time promoted the physical weathering of these carbonates. The second major zone (B, 6400 cal.BP–1996 AD) is divided into four subsections with boundaries at ca. 3500, 2400, and 160cal. BP. The lower part of this zone, B1, is characterized by a gradual decrease in the carbonate-silt fraction and a pronounced increase in the silicate-clay fraction. This is concurrent with the expansion of Picea in the catchment area, which probably stabilized the soil. The middle part, B2 and B3 (3500–160cal. BP), comprises pronounced fluctuations in all elements, especially Ca, Sr, Mn, and Rb, but also in clay and silt. These changes are related to varying intensities of alpine farming. In the same section, Mn/Fe ratios are highly variable, suggesting changes in the mixing regime of the lake with phases of anoxic bottom water. The uppermost section, B4 (since 160cal. BP), is characterized by a steep decline in the silicate fraction and an increase in Ca and Sr. Despite the decrease in the silicate fraction, Pb increases, due to elevated atmospheric input resulting from early metal pollution, are masked by the high natural variability. Generally, changes in vegetation, which correspond to climate changes in the early Holocene and to human activities since ca. 3700cal. BP, are the controlling factor for variations in the geochemical composition of the sediment of Sägistalsee. ©2003 Kluwer Academic Publishers
    Electronic ISSN: 1573-0417
    Topics: Biology , Geosciences
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  • 7
    Publication Date: 2012-04-01
    Description: Atmospheric dusts are an important part of the global climate system, and play an important role in the marine and terrestrial biogeochemical cycles of major and trace nutrient elements. A peat bog record of atmospheric deposition shows considerable variation in dust deposition during the past 15 k.y., with abrupt changes in fluxes at 12, 9.2, 8.4, 7.2, and 6 cal. kyr B.P. Using Nd isotopes and rare earth elements, it is possible to clearly distinguish between volcanic inputs and those driven by climate change, such as the long-term aridification of the Sahara and regional erosion due to forest clearing and soil cultivation activities. Our results indicate that a major dust event in North Africa and Europe preceded the 8.2 kyr B.P. cold event by 200 yr. This dust event may have played an active role in the following climate cooling of the 8.2 kyr B.P. event. Nd isotope evidence also indicates a relatively slow change in dust regime over Europe from 7 to 5 kyr B.P. due to Sahara expansion. These findings show that the inorganic fraction in high-resolution peat records can provide remarkably sensitive indicators of dust load and sources. Our study supports the priority to better identify the impact of dust loading during the Holocene in terms of direct and indirect impacts on environmental and climate changes.
    Print ISSN: 0091-7613
    Electronic ISSN: 1943-2682
    Topics: Geosciences
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  • 8
    Publication Date: 1999-06-08
    Print ISSN: 0028-1042
    Electronic ISSN: 1432-1904
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Published by Springer
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  • 9
    Publication Date: 2009-06-16
    Print ISSN: 1439-0108
    Electronic ISSN: 1614-7480
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Published by Springer
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  • 10
    Publication Date: 2017-10-01
    Print ISSN: 1352-2310
    Electronic ISSN: 1873-2844
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences , Physics
    Published by Elsevier
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