Vyacheslav G. Rumynin: Subsurface Solute Transport Models and Case Histories, with Application to Radionuclide Migration     

Daniela Blessent 《Mathematical Geosciences》2013,45(6):773-775

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Solitons and other solutions to the quantum Zakharov-Kuznetsov equation     

Ghodrat Ebadi  Aida Mojaver  Daniela Milovic  Stephen Johnson  Anjan Biswas 《Astrophysics and Space Science》2012,341(2):507-513

In this paper, we present G′/G-expansion method, exp-function method, modified F-expansion method as well as the traveling wave hypothesis for finding the exact traveling wave solutions of the quantum Zakharov-Kuznetsov equation which arises in quantum magneto-plasmas. By these methods, rich families of exact solutions have been obtained, including soliton solutions. This work continues to reinforce the idea that the proposed methods, with the help of symbolic computation, provide a powerful mathematical tool for solving nonlinear partial differential equations.  相似文献   

Natural background levels for some ions in groundwater of the Campania region (southern Italy)     

Daniela Ducci  Mariangela Sellerino 《Environmental Earth Sciences》2012,67(3):683-693

The aim of the study was the determination of the natural background levels (NBLs) for the ions Na⁺, Cl^?, SO₄ ^2?, As³⁺, F^?, Fe²⁺, and Mn²⁺, in some groundwater bodies of the Campania region (southern Italy). The ??Protocol to evaluate the natural background concentrations?? proposed in 2009 by ISPRA (Italian Institute for Environmental Protection and Research) has been applied to the chemical data set of groundwater of the examined groundwater bodies. These analyses have also been examined following the guidelines of the BRIDGE project (Background cRiteria for the IDentification of Groundwater thrEshold). These approaches to evaluate the Threshold Values (TVs) and the NBLs, based on probability distribution functions, have been applied in many countries by various authors during the last 5?years. Changes applied to ISPRA Protocol in this study concern mainly the preselection criteria, in particular threshold values of specific ions, deriving from the aquifers geochemical features. The preselection criteria of the ISPRA Protocol have been merged with those of the BRIDGE Project in order to define a procedure suitable for the definition of the NBLs in the examined aquifers. The NBL of fluoride for the ??Phlegrean Fields?? and the ??eastern Plain of Naples?? groundwater bodies shows values deeply exceeding the reference value (REF) of 1,500???g/L, ranging between 3,600 and 15,000???g/L. The cause of this very high fluoride content is in the natural features of the aquifers constituted by volcanic and pyroclastic rocks. The volcanic origin of the aquifers is also the reason for the high arsenic content in ??Phlegrean Fields?? groundwater. Here the NBL calculated was about 47???g/L against the drinking water standard value of 10???g/L. The widespread high content of manganese and iron for the groundwater body of the ??eastern Plain of Naples?? is due to the reducing conditions related to the extensive marshlands present in the past. The very high NBL of all the examined ions for the groundwater body of ??Ischia Island?? depends on the existence of a geothermal system.  相似文献   

Leucogranite intruding the South Tibetan Detachment in western Nepal: implications for exhumation models in the Himalayas   总被引：1，自引：0，他引：1  

Rodolfo Carosi  Chiara Montomoli  Daniela Rubatto  Dario Visonà 《地学学报》2013,25(6):478-489

The most popular models regarding the exhumation of the Greater Himalayan Sequence (GHS), such as extrusion, channel flow, critical taper and wedge extrusion, require prolonged activity of the two bounding shear zones and faults, the Main Central Thrust (MCT) and the South Tibetan Detachment (STD). We present the crystallization age of an undeformed leucogranite that intrudes both the GHS and the Tethyan Himalaya Sequence (THS). Zircon and monazite U‐Pb ages in the leucogranite give ages between 23 and 25 Ma constraining, at that time, the end of shearing along the STD. Our results limit the contemporaneous activity of the MCT and STD to a short period of time (~1–2 Ma) and thus argue against exhumation models requiring prolonged contemporaneous activity of the MCT and STD.  相似文献   

Les filons sédimentaires jurassiques de Longobucco-Caloveto (Calabre,Italie); application à l’étude des paléostructures d’une marge téthysienne     

Jean-Pierre Bouillin  Daniela Bellomo 《Geodinamica Acta》2013,26(2):111-120

Résumé

La région de Longobucco-Caloveto, dans le Nord du massif de la Sila, en Calabre, montre de très nombreux filons sédimentaires jurassiques qui traversent des schistes cambro-ordovicien ou des granites hercyniens. Ces filons se répartissent en deux groupes. Les plus anciens, d’âge carixien, sont associés à des failles normales qui ont permis la formation d’un demi-graben rempli par des sédiments du Domérien. Les plus récents, d’âge compris entre le Lias supérieur et le Malm, marquent la fracturation de hauts-fonds qui se sont effondrés au Dogger. Ces filons enregistrent ainsi la formation du segment de la marge de la Téthys auquel correspondent les séries de Longobucco-Caloveto. L’étude des relations entre les filons sédimentaires et la fracturation permet de montrer, dans une région pourtant fortement tectonisée au Tertiaire, que différentes failles sont d’âge jurassique : certaines d’entre-elles sont recoupées par des filons et donc antérieures à ceux-ci; d’autres systèmes de filons sont parallèles à des systèmes de failles et donc postérieurs à ces derniers ou contemporains. Us filons sédimentaires apparaissent ainsi comme un moyen intéressant, bien qu’encore peu utilisé, de caractén-sation des dispositifs paléotectoniques.  相似文献   

Spectral and petrologic analyses of basaltic sands in Ka'u Desert (Hawaii) – implications for the dark dunes on Mars     

Daniela Tirsch  Robert Anthony Craddock  Thomas Platz  Alessandro Maturilli  Jörn Helbert  Ralf Jaumann 《地球表面变化过程与地形》2012,37(4):434-448

Dark aeolian deposits on Mars are thought to consist of volcanic materials due to their mineral assemblages, which are common to basalts. However, the sediment source is still debated. Basaltic dunes on Earth are promising analogs for providing further insights into the assumed basaltic sand dunes on Mars. In our study we characterize basaltic dunes from the Ka'u Desert in Hawaii using optical microscopes, electron microprobe, and spectral analyses. We compare the spectra of terrestrial and Martian dune sands to determine possible origins of the Martian dark sediments. Our results show that the terrestrial sands consist primarily of medium to coarse sand‐sized volcanic glass and rock fragments as well as olivine, pyroxene, and plagioclase minerals. Grain shapes range from angular to subrounded. The sample composition indicates that the material was derived from phreatomagmatic eruptions partially with additional proportions of rock fragments from local lava flows. Grain shape and size indicate the materials were transported by aeolian processes rather than by fluvial processes. Spectral analyses reveal an initial hydration of all terrestrial samples. A spectral mineralogical correlation between the terrestrial and Martian aeolian sands shows a similarity consistent with an origin from volcanic ash and lava. We suggest that the Martian deposits may contain similar abundances of volcanic glass, which has not yet been distinguished in Martian spectral data. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Impact of pond aquaculture effluents on seagrass performance in NE Hainan,tropical China     

Lucia S. Herbeck  Miriam Sollich  Daniela Unger  Marianne Holmer  Tim C. Jennerjahn 《Marine pollution bulletin》2014

The impact of pond aquaculture effluents on the distribution and performance of seagrasses was examined in NE Hainan, tropical China. Samples were taken along transects in three back-reef areas with different extent of aquaculture production in their hinterland. High δ¹⁵N in seagrass leaves and epiphytes (6–9‰) similar to values in pond effluents documented aquaculture as dominant nitrogen source in the back-reefs with decreasing impact with distance from shore. Seagrass species abundance, shoot density and biomass were lower and concentrations of nutrients, chlorophyll and suspended matter were higher at nearshore sites with high and moderate pond abundance than at the control site. High epiphyte loads and low δ³⁴S in seagrass leaves suggest temporal shading and sulphide poisoning of the nearshore seagrasses. Observed gradients in environmental parameters and seagrass performance indicate that the distance from the pond outlets and size of the adjacent pond agglomeration are major determinants of seagrass degradation.  相似文献   

Biochemical and microbial features of shallow marine sediments along the Terra Nova Bay (Ross Sea,Antarctica)   总被引：1，自引：0，他引：1  

Franco Baldi  Davide Marchetto  Francesco Pini  Renato Fani  Luigi Michaud  Angelina Lo Giudice  Daniela Berto  Michele Giani 《Continental Shelf Research》2010

Shallow marine sediments were collected from seven stations (three of which located at Gerlache Inlet, two at Tethys Bay, one at Adelie Cove and one just beneath the Italian Research Base) along the Terra Nova Bay coast (Ross Sea, Antarctica). Their chemical, biochemical and microbiological properties were studied in order to provide further insights in the knowledge of this Antarctic benthic ecosystem. Overall, the organic carbon (OC) represented the major fraction of total carbon (TC) and displayed concentrations similar to or slightly lower than those previously measured in Antarctic bottom sediments. The biopolymeric carbon within OC ranged from 4.1% to 19.9% and showed a wide trophic range (65–834 μg g⁻¹ d.w.). Proteins (PRT) represented on average the main biochemical class contributing to labile organic carbon, followed by lipids (LIP) and carbohydrates (CHO). The activity of aminopeptidase, β-d-glucosidase, alkaline phosphatase and esterase was checked, giving the highest values at Tethys Bay and at the deepest water sediments. The principal component analysis, which was computed considering physical, chemical (elemental and biochemical sedimentary composition) and microbiological parameters (including bacterial abundance, ectoenzymatic activities, T-RFs richness and diversity indices), allowed to obtain two main clusters (“Tethys Bay” and “other stations”). Based on data obtained, two representative 16S rRNA clone libraries using samples from Tethys Bay and Gerlache Inlet were constructed. The sequences of 171 clones were compared to those available in public databases to determine their approximate phylogenetic affiliations. Both aerobic and anaerobic bacteria were disclosed, with the majority of them affiliated with the Gamma- and Deltaproteobacteria, Bacteroidetes and Acidobacteria. The occurrence of strictly anaerobic bacteria suggests that sediments might also undergo anoxic conditions that, in turn, could favor the accumulation of PRT in respect to CHO, assuming that fermentation of amino acids is slower than that of sugars from decomposing polysaccharides.  相似文献   

Lowermost Mantle Velocity Estimations Beneath the Central North Atlantic Area from Pdif Observed at Balkan,East Mediterranean,and American Stations     

Marian Ivan  Daniela Veronica Ghica  Andrej Gosar  Panagiotis Hatzidimitriou  Rami Hofstetter  Gulten Polat  Rongjiang Wang 《Pure and Applied Geophysics》2015,172(2):283-293

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The Role of Groundwater for Lake‐Water Quality and Quantification of N Seepage          下载免费PDF全文

Jacob Kidmose  Peter Engesgaard  Daniela A. Oliveira Ommen  Bertel Nilsson  Mogens R. Flindt  Frede Ø. Andersen 《Ground water》2015,53(5):709-721

The heterogeneous nature of both groundwater discharge to a lake (inflow) and nitrate concentrations in groundwater can lead to significant errors in calculations of nutrient loading. Therefore, an integrated approach, combining groundwater flow and transport modelling with observed nitrate and ammonium groundwater concentrations, was used to estimate nitrate loading from a catchment via groundwater to an oligotrophic flow‐through lake (Lake Hampen, Denmark). The transport model was calibrated against three vertical nitrate profiles from multi‐level wells and 17 shallow wells bordering a crop field near the lake. Nitrate concentrations in groundwater discharging to the lake from the crop field were on average 70 times higher than in groundwater from forested areas. The crop field was responsible for 96% of the total nitrate loading (16.2 t NO₃/year) to the lake even though the field only covered 4.5% of the catchment area. Consequently, a small change in land use in the catchment will have a large effect on the lake nutrient balance and possible lake restoration. The study is the first known attempt to estimate the decrease of nitrate loading via groundwater to a seepage lake when an identified catchment source (a crop field) is removed.  相似文献