Search results for " basin"
showing 10 items of 838 documents
On the occurrence and distribution of Calanipeda aquaedulcis Kritschagin, 1873 (Copepoda, Calanoida, Pseudodiaptomidae) in Sicily, Italy, with some n…
2019
The only population of the pseudodiaptomid copepod Calanipeda aquaedulcis Kritschagin, 1873 to date reported to occur in Sicily disappeared at the beginning of the XXI century due to deep environmental changes which affected the single site (Lake Biviere di Gela) known for this species on the island. In that site C. aquaedulcis is now replaced by Copidodiaptomus numidicus (Gurney, 1909), a diaptomid copepod whose distribution has been greatly increasing since the second half of the last century. In the present note, the occurrence of C. aquaedulcis in 12 novel water bodies spread throughout Sicily is reported, and some environmental data on the sites where the species was collected are prov…
Perfluorinated Compounds Distribution and Source Identification in Sediments of Lake Victoria Gulf Basin
2011
Perfluorooctanoic acid and perfluorooctane sulfonate were determined in the sediments from Winam Gulf, which is in the Kenyan side of Lake Victoria and in its source rivers. The sources of perfluorinated compounds within the Gulf of Lake Victoria have been identified and their levels determined for the first time, in this study, using SPE and HPLC-MS-MS analytical methodology. Variability in the concentrations of perfluorooctanoic acid and perfluorooctane sulfonate ranged from 1.4–99.1 and <1–57.5 ng/g in river sediments, respectively, which was higher than concentrations obtained from lake sediments (range perfluorooctanoic acid <1–24.1 ng/g and perfluorooctane sulfonate <1–4.0 ng/g). The …
Middle Miocene–Early Pliocene wedge-top basins of NW Sicily (Italy): constraints for the tectonic evolution of a ‘non-conventional’ thrust belt, affe…
2014
The study of geological evolution of a multiphase orogenic belt is complex, expecially when the tectonic events are superimposed in a coaxial fashion. The Sicilian fold-and-thrust belt represents an interest- ing case study, as a non-coaxial superimposition of structures is recognizable, owing to large synkinematic clockwise rotations during each of two subsequent compressional events. These rotations involved also the syntectonic basins that developed in the wedge-top depozone. This study aims to constrain the tectono-depo- sitional evolution of the NW Sicily fold-and-thrust belt and the associated wedge-top depozone between the middle Miocene and the early Pliocene. Integrated analyses of…
Variability of near-surface saturated hydraulic conductivity for the clay soils of a small Sicilian basin
2019
Abstract Proper characterization of saturated hydraulic conductivity, Ks, of clay soils in a hillslope or a basin is still a challenge for soil science. In this investigation, the clay soils of the Maganoce (Sicily, Italy) basin were sampled at 19 sampling sites by the BEST procedure of soil hydraulic characterization. More OM implied less compact conditions (decreasing dry soil bulk density; coefficient of determination, R2 = 0.67), more stability to water of the soil aggregates (increasing water stable aggregates; R2 = 0.83) and, consequently, higher Ks values (R2 = 0.54). Variability of Ks was lower in the steeper zones of the basin than in the flatter ones. A comparison with the Ks data…
Sediment delivery processes and the spatial distribution of caesium-137 in a small Sicilian basin
1998
The sediment delivery processes occurring in a small Sicilian basin are modelled using the spatially distributed SEDD model recently proposed by Ferro and Minacapilli. The model is applied by using soil data (grain-size distribution, organic matter content, etc.) of 129 samples uniformly distributed over the study area and compiling the available information (topographic map, soil data, etc.) into a Geographical Information System. Finally, the predictive capability of the distributed sediment delivery approach is tested experimentally using the caesium-137 measurement technique. The comparison between calculated sediment yield and the corresponding measured caesium-137 loss is used to vali…
Natural organic matter export from boreal catchments (the Salaca River basin, Latvia) and its influencing factors
2012
A noteworthy increase in the organic matter concentration and export, as well as water colour, in the catchments of the Salaca River has been observed during the last decades. This study investigates factors behind this increase: the impact of climate, land use and human loading changes on the concentrations and export of the organic matter in the Salaca River/Lake Burtnieks catchments. Proportion of wetlands in the river basin, type of land use, and runoff regime can be considered as the main factors influencing the organic carbon loadings. Despite a steady overall tendency of increase, considerable oscillations of organic matter loadings influenced by the changes in the river discharge re…
Influence of anthropogenic activity on the lead isotope signature of Thau Lake sediments (southern France): origin and temporal evolution
2000
Lead concentrations and isotopic compositions were determined on both bulk sediments deposited in the Thau lake in southern France during the last 200 years, and leachates derived from a series of sequential leachings of the sediments, making it possible to identify the sources, natural (i.e. indigenous lithologic) or anthropogenic, and to quantify the different inputs of Pb. Two distinct inputs of Pb could be distinguished. One of these corresponds to the terrigenous material entering the basin, representative of the local natural Pb ‘background’. Its supply remained steady most of the time with 206Pb/207Pb ratios of 1.200±0.003, except at the time of heavy storms producing voluminous and …
δ18O values of coexisting brachiopods and fish: Temperature differences and estimates of paleo–water depths
1998
To estimate vertical thermal gradients and paleo–water depths to marine platforms we present a new method based on the difference between δ 18 O values of contemporaneous brachiopod carbonate and fish phosphate. Present-day marine fauna of well-known ecology from the surface to the sea floor record isotopic temperatures that agree with measured temperatures. We predict distributions of isotopic data that result from sampling strategy, basin morphology, and fauna ecology and discuss limitations. Application of the method to the Jurassic Paris-London basin gives vertical thermal variations of up to 14 °C associated with depths varying from a few meters to 170 ± 30 m. The estimated depths are …
Climate change of Benin for the period 1950-2010 and its impact on surface water.
2016
6 pages; International audience; In West Africaand Benin in particular, variability / climate change affects the availability of surface water resources. Thus,this study aims to analyze the rainfall field of Benin from the fifty three (53) meteorological stations from 1950to 2010 and to detect the rainfall amounts and the average temperature of six synoptic stations and thehydrometric stations of Niger river in, Benin, Pendjari, Ouémé, Mono and Couffo. From the analysis a trend ofdeclining precipitation and of rising temperatures have been highlighted. This decrease is more pronounced inthe Sudanese area (north of 8 ° N) and in the sub-equatorial area (south of 8 ° N). This decrease of prec…
Application d’un modèle conceptuel à l’analyse de la dynamique hydrométéorologique des crues dans un bassin-versant en milieu tropical humide : cas d…
2015
7 pages; International audience; Application of a conceptual model to analysis of dynamic hydrometeorological flood in a pool - side in tropicalmoist environment : the case of Mono river. The objective of this study is to analyze the dynamics of the basinhydrometeorological and distribution of incoming flood dam Nangbéto to assess the risk of flooding in the lower valley of theriver. The data used are: daily flows of Mono (m3.s-1) and Nangbéto Athiémé, evapotranspiration (mm / day, calculatedaccording to the method Oudin et al., 2005) and the average precipitation over the basin (mm / day) covering the period1988- 2010. The method of spatial interpolation of rainfall tested is that of ordin…