Search results for "Waters"
showing 10 items of 281 documents
Moisture source in the Hyblean mountains region (south-eastern Sicily,Italy):Evidence from stable isotopes signature
2006
Abstract Here the authors present results of an isotope study on precipitation collected during a 2-a period from a rain-gauge network consisting of 6 stations located at different elevations in the Hyblean Mountains (HM) region, in south-eastern Sicily. The slope of the local meteoric water line ( δD = 6.50 δ 18 O + 9.87) obtained for the region suggests that precipitation is affected by evaporation during rainfall events. The main variations in rainwater isotope composition are due to seasonal effects and elevation. An average 2 H excess value of +21.2‰ was found for precipitation events less affected by evaporation (i.e. when the rainfall was >65 mm/month). The spatial distribution of O…
Diffusive Modeling of Aggradation and Degradation in Artificial Channels
2008
The unsteady flow and solid transport simulation problem in artificial channels is solved using a three-equation model, coupled with a local erosion law. The three equations are the water mass and momentum balance equations, as well as the total solid load balance equation. It is shown that even during severe hydrological events inertial terms can be neglected in the momentum equation without any substantial change in the solution sought. Empirical equilibrium formulas were used to estimate the solid load as a function of the flow variables. Local erosion, due to the scour generated at the jump between two channels connected at different bottom elevations, was estimated adapting a literatur…
Atmospheric correction of ENVISAT/MERIS data over inland waters: Validation for European lakes
2010
Traditional methods for aerosol retrieval and atmospheric correction of remote sensing data over water surfaces are based on the assumption of zero water reflectance in the near-infrared. Another type of approach which is becoming very popular in atmospheric correction over water is based on the simultaneous retrieval of atmospheric and water parameters through the inversion of coupled atmospheric and bio-optical water models. Both types of approaches may lead to substantial errors over optically-complex water bodies, such as case II waters, in which a wide range of temporal and spatial variations in the concentration of water constituents is expected. This causes the water reflectance in t…
Zr- Hf Fractionation During Water-Rock Interaction
2017
International audience; Zr and Hf are two elements having same ionic charge and similar ionic size at a given coordination number. Despite the Zr/Hf ratio is considered to be quite constant in meteorites and lithospheric rocks, seawaters collected from the surface down to varying depths of several Pacific Ocean stations reveal that the Zr/Hf ratio increases by one order of magnitude. Very recent studies have shown that, in both ground waters and lake waters, the Zr/Hf ratio is either higher or lower compared to the interacting minerals displaying a large variability in the distribution of these twin elements. In this communication the possible processes responsible for such a large fraction…
Phosphogenesis in the Bonarelli Level from northwestern Sicily, Italy: petrographic evidence of microbial mediation and related REE behaviour
2010
Phosphogenesis at the base of the Bonarelli Level from the Calabianca stratigraphic section (northwestern Sicily) was investigated using X-ray diffraction, scanning electron microscopy, X-ray fluorescence, and stable-isotope mass spectrometry. The anoxic event onset is marked by high P(2)O(5tot) concentrations related to the presence of authigenic carbonate-fluorapatite. This mineral is poorly crystallized and occurs in three different forms: (i) fish debris locally showing evidence of re-crystallization, (ii) phosphatically cemented layers, and (iii) dense aggregates of microcrystals. Petrographic features are indicative of a microbial genesis for the carbonate-fluorapatite. Conversely, th…
Chemical and isotopic characterization of Ischia hydrothermal system: an interpretative model of fluids circulation
2009
Identità queer e spazi della comunità tra teoria e fiction: i casi di Jeanette Winterson e Sarah Waters
2014
A comparison of statistical methods and multi-criteria decision making to map flood hazard susceptibility in Northern Iran
2018
In north of Iran, flood is one of the most important natural hazards that annually inflict great economic damages on humankind infrastructures and natural ecosystems. The Kiasar watershed is known as one of the critical areas in north of Iran, due to numerous floods and waste of water and soil resources, as well as related economic and ecological losses. However, a comprehensive and systematic research to identify flood-prone areas, which may help to establish management and conservation measures, has not been carried out yet. Therefore, this study tested four methods: evidential belief function (EBF), frequency ratio (FR), Technique for Order Preference by Similarity To ideal Solution (TOP…
Yttrium and lanthanides in human lung fluids, probing the exposure to atmospheric fallout.
2011
International audience; Inhalation of airborne particles can produce crystallization of phosphatic microcrysts in intraaveolar areas of lungs, sometimes degenerating into pulmonary fibrosis. Results of this study indicate that these pathologies are induced by interactions between lung fluids and inhaled atmospheric dust in people exposed to volcanic dust ejected from Mount Etna in 2001. Here, the lung solid-liquid interaction is evaluated by the distribution of yttrium and lanthanides (YLn) in fluid bronchoalveolar lavages on selected individuals according the classical geochemical approaches. We found that shale-normalised patterns of yttrium and lanthanides have a 'V shaped' feature corre…
Local validation of MODIS sensor sea surface temperature on western Mediterranean shallow waters
2014
The sea surface temperature (SST) estimated from MODIS Aqua products (daytime and nighttime 11 μm and night 4 μm) has been correlated with field data taken at three depths (15, 50, 100 cm) in a Western Mediterranean coastal area. The comparison has allowed us to analyze the uncertainty in the estimation of this parameter in coastal waters using low spatial resolution satellite images. The results show that the daytime SST_11 μm product obtains fittest statistical values: RMSE (root mean square error) and r2 (Pearson’s correlation coefficient) of 1°C and 0.96, respectively, for 50 cm depth.