Fe,Mn, P and S Speciation in Sediments from the Capivara Hydroelectric Dam Lake (Brazil) as an Indicator of Anthropogenic Influences     

Wagner José Barreto  Dilson Norio Ishikawa  Ieda Spacino Scarminio  João de Souza Costa  Paulo dos Santos Nora  Miriam de Fatima Soares  Romilaine Mansano Nicolau  Adriana Celeste Esteves Gonçalves  Sonia Regina Giancoli Barreto 《洁净——土壤、空气、水》2008,36(4):353-359

The conservation of large water resources is essential for the preservation of human life. The quantification and, more importantly, the speciation of chemical substances that indicate the presence of anthropogenic contamination in water resources are of great importance. This paper presents the results of analysis for the determination of organic, inorganic and total phosphorus, pseudo‐sulfur, and iron and manganese, in five fractions, in water sediments collected from the Capivara Hydroelectric Power Plant, Brazil. A study on the seasonal variation of these parameters was conducted, with data having been collected in the winter and in the summer, at two sites along the dam, 5 km apart, close to the city of Primeiro de Maio. Phosphorous was found in sediments and adjacent soil in the organic form (OP), and was used as an indicator of anthropogenic influence on the reservoir banks. Speciation of potentially toxic Mn showed that it is present in the exchangeable fraction of the 0–5 cm depth layer (sediment/water interface), making its transfer to the water column possible. Results from this study showed that domestic and industrial effluent treatment measures are needed for the preservation of the quality of aquatic environments.  相似文献   

Northern Eurasian lakes – late Quaternary glaciation and climate history – introduction     

Martin Melles  John Inge Svendsen  Grigory Fedorov  Bernd Wagner 《Boreas: An International Journal of Quaternary Research》2019,48(2):269-272

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On the field-aligned scale length of the V-shaped auroral potential structure     

J.S. Wagner  J.R. Kan 《Planetary and Space Science》1985,33(1):89-96

It is found, by means of particle simulations, that the field-aligned scale length of the V-potential along auroral-field lines depends on the convergence of the magnetic-field lines. In a uniform magnetic field, the potential drop is localized in a double layer with a field-aligned scale length of the order of the Debye length. In a converging magnetic field, the potential drop is shown to be extended with a field-aligned scale length much greater than the Debye length. The converging magnetic field appears to contribute to the retention of trapped electrons confined between the magnetic mirror and the electrostatic potential-barrier. When a background plasma is included in the simulation, the potential structure is shown to detach from the ionospheric boundary.  相似文献   

Geomorphological and Pedological Investigations on the Glacial History of the Kali Gandaki (Nepal Himalaya)     

Markus Wagner 《GeoJournal》2005,62(3-4):91-113

In semi-arid orographic left tributaries of the Kali Gandaki at the northern and western flank of the Nilgiri Himal, glacio-geomorphological and pedological investigations were carried out on prehistoric moraines. Geomorphological relief analysis was derived from other literature and the own fieldwork of the author. The resulting glacial chronology was used as benchmark to explore the limits of different pedological dating methods regarding the degree of soil development. These methods are based on iron fractionation, total element contents and particle size distribution. In general the different glacial stages are mirrored correctly in the relative graduation of soil development. The ratio of well crystallised pedogenic iron-oxides to the total iron content and the ratio fine clay to total clay are most suitable, because they are almost independent from existing changes in the lithological composition. The total element based weathering indices are less suitable, because they react highly sensitive to the geology dependent shift to higher carbonate contents. Most of the grain size based weathering indices are inapplicable because of the typically high textural variability within till deposits.  相似文献   

A first approach to calculate BIOCLIM variables and climate zones for Antarctica     

Wagner  Monika  Trutschnig  Wolfgang  Bathke  Arne C.  Ruprecht  Ulrike 《Theoretical and Applied Climatology》2018,131(3-4):1397-1415

Theoretical and Applied Climatology - For testing the hypothesis that macroclimatological factors determine the occurrence, biodiversity, and species specificity of both symbiotic partners of...  相似文献   

Variations in the accuracy of gravity recovery due to ground track variability: GRACE,CHAMP, and GOCE   总被引：4，自引：2，他引：2  

J. Klokočník  C. A. Wagner  J. Kostelecký  A. Bezděk  P. Novák  D. McAdoo 《Journal of Geodesy》2008,82(12):917-927

Following an earlier recognition of degraded monthly geopotential recovery from GRACE (Gravity Recovery And Climate Experiment) due to prolonged passage through a short repeat (low order resonant) orbit, we extend these insights also to CHAMP (CHAllenging Minisatellite Payload) and GOCE (Gravity field and steady state Ocean Circulation Explorer). We show wide track-density variations over time for these orbits in both latitude and longitude, and estimate that geopotential recovery will be as widely affected as well within all these regimes, with lesser track density leading to poorer recoveries. We then use recent models of atmospheric density to estimate the future orbit of GRACE and warn of degraded performance as other low order resonances are encountered in GRACE’s free fall. Finally implications for the GOCE orbit are discussed.  相似文献   

A numerical investigation of scattering effects for teleseismic plane wave propagation in a heterogeneous layer over a homogeneous half-space     

Gregory S. Wagner  Charles A. Langston 《Geophysical Journal International》1992,110(3):486-500

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Geologie in der pädagogischen Presse 1911     

P. Wagner 《International Journal of Earth Sciences》1912,3(3):195-203

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Source parameters of some large earthquakes in Northern Aegean determined by body waveform inversion   总被引：1，自引：0，他引：1  

Anastasia A. Kiratzi  Gregory S. Wagner  Charles A. Langston 《Pure and Applied Geophysics》1991,135(4):515-527

Average source parameters for three large North Aegean events are obtained from body wave inversion for the moment tensor. The parameters for the events are as follows: The events exhibit dextral strike-slip faulting with theT axis striking NS and nearly horizontal, implying extension in this direction. The focal mechanisms obtained are in agreement with the seismotectonic regime of the North Aegean. It is known that the region is tectonically controlled by the existence of the strike-slip Anatolian fault and its westward continuation in the Aegean, as well as the NS extension the whole Aegean area undergoes.The components of the moment tensor show that the region is dominated by compression in the EW direction which is encompassed by extension in the NS direction. All the events were found to be shallow (10 km) with a source time function of approximately 8 s duration and small stress drop values.The teleseismic long period verticalP-waves exhibited distortions, that could be attributed to lateral inhomogeneities in the source structure or more probably to a nonflat water-crust interface.  相似文献   

A tephrostratigraphic record for the last glacial–interglacial cycle from Lake Ohrid,Albania and Macedonia     

Hendrik Vogel  Giovanni Zanchetta  Roberto Sulpizio  Bernd Wagner  Norbert Nowaczyk 《第四纪科学杂志》2010,25(3):320-338

Here we present a tephrostratigraphic record (core Co1202) recovered from the northeastern part of Lake Ohrid (Republics of Macedonia and Albania) reaching back to Marine Isotope Stage (MIS) 6. Overall ten horizons (OT0702‐1 to OT0702‐10) containing volcanic tephra have been recognised throughout the 14.94 m long sediment succession. Four tephra layers were visible at macroscopic inspection (OT0702‐4, OT0702‐6, OT0702‐8 and OT0702‐9), while the remaining six are cryptotephras (OT0702‐1, OT0702‐2, OT0702‐3, OT0702‐5, OT0702‐7 and OT0702‐10) identified from peaks in K, Zr and Sr intensities, magnetic susceptibility measurements, and washing and sieving of the sediments. Glass shards of tephra layers and cryptotephras were analysed with respect to their major element composition, and correlated to explosive eruptions of Italian volcanoes. The stratigraphy and the major element composition of tephra layers and cryptotephras allowed the correlation of OT0702‐1 to AD 472 or AD 512 eruptions of Somma‐Vesuvius, OT0702‐2 to the FL eruption of Mount Etna, OT0702‐3 to the Mercato from Somma‐Vesuvius, OT0702‐4 to SMP1‐e/Y‐3 eruption from the Campi Flegrei caldera, OT0702‐5 to the Codola eruption (Somma‐Vesuvius or Campi Flegrei), OT0702‐6 to the Campanian Ignimbrite/Y‐5 from the Campi Flegrei caldera, OT0702‐7 to the Green Tuff/Y‐6 eruption from Pantelleria Island, OT0702‐8 to the X‐5 eruption probably originating from the Campi Flegrei caldera, OT0702‐9 to the X‐6 eruption of generic Campanian origin, and OT0702‐10 to the P‐11 eruption from Pantelleria Island. The fairly well‐known ages of these tephra layers and parent eruptions provide new data on the dispersal and deposition of these tephras and, furthermore, allow the establishment of a chronological framework for core Co1202 for a first interpretation of major sedimentological changes. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献