Search results for "WATERS"

Sulphur Stored in Forest Soils and the Relative Importance of Organic and Inorganic Forms. Examples from Mont-Lozère (Southern Massif Central)

1995

From studies initiated in 1981, the mean annual hydrochemical budget established in three experiment watersheds at Mont-Lozere demonstrated that sulphur is retained in soils and in arenaceous formations (Lelong et al. 1990). Soils were developed on weathered granite materials that were strongly reworked by periglacial processes. One watershed is covered with grasses (Bassin de la Cloutasse) and the two others by forest. A beech coppice (Fagus sylvatica L.) and a Norway spruce forest (Picea abies (L.) Karst., hereafter shortened to “spruce”) occupy the Bassin de La Sapine (54 ha) and the Bassin of La Latte (20 ha), respectively. Unfortunately, as a result of a parasite attack, a large part o…

First record of arctodiaptomus wierzejskii (Richard, 1888) (Copepoda Calanoida Diaptomidae) from Malta

2020

Diaptomid copepods belonging to the genus Arctodiaptomus Kiefer, 1932 were collected in two temporary water bodies in Malta. The morphological identification of the collected specimens proved that they belong to Arctodiaptomus wierzejskii (Richard, 1888) even if a morphological peculiarity pertaining to the morphology of the male right antennule of the Maltese populations was observed and here briefly discussed. This finding constitutes the first record of a calanoid copepod from the inland waters of the Maltese Islands.

Predicting gully occurrence at watershed scale: Comparing topographic indices and multivariate statistical models

2020

In this study, the ability of five topographic indices to predict the gully trajectories observed in two adjacent watersheds located in Sicily (Italy) was evaluated. Two of these indices, named MSPI and MTWI, as far as we know, have never been employed to this aim. They were obtained by multiplying the stream power index (SPI) and the topographic wetness index (TWI), respectively, by the convergence index (CI). The predictive ability of the topographic indices was measured by using both cut-off independent (AUC: area under the receiver operating characteristic curve) and dependent statistics (Cohen's kappa index κ, sensitivity, specificity). These statistics were calculated also for 100 MAR…

Comprehensive dataset of shotgun metagenomes from stratified freshwater lakes and ponds

2020

AbstractStratified lakes and ponds featuring steep oxygen gradients are significant net sources of greenhouse gases and hotspots in the carbon cycle. Despite their significant biogeochemical roles, the microbial communities, especially in the oxygen depleted compartments, are poorly known. Here, we present a comprehensive dataset including 267 shotgun metagenomes from 41 stratified lakes and ponds mainly located in the boreal and subarctic regions, but also including one tropical reservoir and one temperate lake. For most lakes and ponds, the data includes a vertical sample set spanning from the oxic surface to the anoxic bottom layer. The majority of the samples were collected during the o…

Helium isotopes distribution in groundwater and thermal waters of Tunisia: relationship to tectonics and geology

2008

DEEP RESERVOIR TEMPERATURES OF LOW-ENTHALPY GEOTHERMAL SYSTEMS IN TUNISIA: NEW CONSTRAINTS FROM CHEMISTRY OF THERMAL WATERS

2012

Tunisia is characterized by hot and warm groundwaters (temperature up to 75 °C) which represent the surface manifestation of geothermal systems hosted in carbonate-evaporite rock sequences. The T-conditions of Tunisia deep thermal reservoirs are here evaluated for the first time at the regional scale. The results here shown clearly highlight the limitations inherent in the application of common geothermometric methods in the estimation of equilibrium temperatures in sedimentary environments. The modeling approach proposed by Chiodini et alii (1995), which makes use of the ratios between dissolved HCO3, SO4 and F, provides the most reliable results, and allows us to derive equilibrium temper…

Regional variations in the chemical and helium–carbon isotope composition of geothermal fluids across Tunisia

2011

Abstract Tunisia has numerous thermo-mineral springs. Previous studies have shown that their chemical composition and occurrence are strongly influenced by the regional geology. However little work has been done so far to study the isotopic composition of volatiles associated with these geothermal manifestations. Here, we report on the results of an extensive survey of both natural hot springs and production wells across Tunisia, aimed at investigating the spatial distribution of thermal fluids' geochemical characteristics and He–C isotopic composition. The chemistry of the analyzed samples highlights the heterogeneity of the water mineralization processes in Tunisia, as a consequence of th…

Simulation of the Propagation of Tsunamis in Coastal Regions by a Two-Dimensional Non-Hydrostatic Shallow Water Solver

2017

Due to the enormous damages and losses of human lives in the inundated regions, the simulation of the propagation of tsunamis in coastal areas has received an increasing interest of the researchers. We present a 2D depth-integrated, non- hydrostatic shallow waters solver to simulate the propagation of tsunamis, solitary waves and surges in coastal regions. We write the governing continuity and momentum equations in conservative form and discretize the domain with unstructured triangular Generalized Delaunay meshes. We apply a fractional- time-step procedure, where two problems (steps) are consecutively solved. In the first and in the second step, we hypothesize a hydrostatic and a non-hydro…

Sicilian transitional waters: Current status and future development

2010

To appraise the current knowledge of Sicilian transitional waters (TWs), a review was undertaken of the information available on these ecosystems. In detail, a synthesis of the current status is reported, highlighting for each area the ecological features and status, historical data, conservation regime, environmental emergencies and anthropic pressures to which they are subject. The Sicilian TWs reviewed include coastal ponds and lakes, mires and areas with active and nonactive saltworks. Almost all of these ecosystems are affected by several protection regimes because of their high naturalistic value, although current knowledge is limited and fragmented. A few areas have received more att…

Occurrence of priority pollutants in WWTP effluents and Mediterranean coastal waters of Spain

2011

A comprehensive study aimed at evaluating the occurrence, significance of concentrations and spatial distribution of priority pollutants (PPs) along the Comunidad Valenciana coastal waters (Spain) was carried out in order to fulfil the European Water Framework Directive (WFD). Additionally, PP concentrations were also analysed in the effluent of 28 WWTPs distributed along the studied area. In coastal waters 36 organic pollutants of the 71 analysed, including 26 PPs were detected although many of them with low frequency of occurrence. Only 13 compounds, which belong to four different classes (VOCs, organochlorinated pesticides, phthalates and tributyltin compounds (TBT)) showed a frequency o…