Search results for "Voir"

Phytoplankton dynamics in a shallow, hypertrophic reservoir (Lake Arancio, Sicily)

1994

Phytoplankton abundance and composition in the hypertrophic man-made Lake Arancio was analyzed, based on a programme of weekly sampling from May 1990 to November 1991 and supported by measurements of limnological parameters. The highest value of phytoplankton biomass (78 mg l-1) was observed in October 1990, during a bloom of the desmid Closterium limneticum var. fallax, while the lowest (0.15 mg l-1) was measured in April 1991. During spring, autumn and winter 1990, species of the genus Closterium dominated the community, in the sequence: C. aciculare, C. limneticum var. fallax, C. limneticum. The summer community was more diverse with the predominance of organisms belonging to Chlorophyce…

Determination of Changes in the Quality of Surface Water in the River—Reservoir System

2021

Assessing the changing parameters of water quality at different points in the river–reservoir system can help prevent river pollution and implement remedial policies. It is also crucial in modeling water resources. Multivariate statistical analysis is useful for the analysis of changes in surface water quality. It helps to identify indicators that may be responsible for the eutrophication process of a reservoir. Additionally, the analysis of the water quality profile and the water quality index (WQI) is useful in assessing water pollution. These tools can support and verify the results of a multivariate statistical analysis. In this study, changes in water quality parameters of the Turawa r…

Dynamics of hydrofracturing and permeability evolution in layered reservoirs

2015

International audience; A coupled hydro-mechanical model is presented to model fluid driven fracturing in layered porous rocks. In the model the solid elastic continuum is described by a discrete element approach coupled with a fluid continuum grid that is used to solve Darcy based pressure diffusion. The model assumes poro-elasto-plastic effects and yields real time dynamic aspects of the fracturing and effective stress evolution under the influence of excess fluid pressure gradients. We show that the formation and propagation of hydrofractures are sensitive to mechanical and tectonic conditions of the system. In cases where elevated fluid pressure is the sole driving agent in a stable tec…

The dissolution of gypsum of Disueri reservoir left bank

2011

Results of a laboratory research programme on the rate of dissolution of selenitic gypsum are reported and discussed. The tested gypsum samples have been recovered from boreholes drilled in a thick layer outcropping on the left bank of Disueri reservoir located near Gela in Sicily. The tests carried out demonstrate that the rate of dissolution Rd depends essentially upon the velocity v of water flowing over the surface of the gypsum. Values of Rd range from 0.94 to 3 kg/(m2 • day) for v values from 0.05 to 0.20 m/s. Such high rates can account both for the rapid evolution of the existing cavities and for the creation of new caves within the gypsum mass subsequent to the impounding of the re…

Assessment of pahs and selected pesticides in shallow groundwater in the highest protected areas in the Opole region, Poland

2014

The ground water quality was determined after the analyses of water samples from 18 wells. The wells were in the Groundwater Area with the Highest Protection (Triassic water, Opole region, Poland), rural build up. The water table level was low: 0.5 – 18.0 m below the ground surface level (except for one artesian well). The following parameters were determined: pH, EC, colour, ammonium, nitrite, nitrate, dissolved orthophosphate, total phosphorus, dissolved oxygen, BOD, COD-Mn, COD-Cr, humic substances, chloride, sulphate, total hardness, alkalinity, dry residue PAHs (16 compounds), pesticides (6 compounds), however, only selected data were presented in this paper. In all the analysed water …

Eco-epidemiology of tick- and rodent-borne pathogens in boreal forests

2017

Infectious diseases are amongst the ten major causes of human mortality worldwide, 60% of them being animal-borne. Variations of abiotic and biotic conditions are likely to modify the transmission of parasites and pathogens within reservoir species, and, as a consequence, alter the zoonotic risk for human. My thesis aims at elucidating the dynamics and mechanisms of the maintenance of ticks, tick-borne pathogens (TBPs) and the Puumala hantavirus (PUUV) in the reservoir host, the bank vole (Myodes glareolus, BV). In Northern Europe, tick-borne diseases are growing in importance to human because of the latitudinal expansion of the tick Ixodes ricinus. Field monitoring revealed that I. ricinus…

Valutazioni igienico-sanitarie delle acque in tre invasi artificiali della provincia di Palermo destinate al consumo umano

1998

We report the physico-chemical and bacteriological characteristics of three Sicilian reservoirs. The aim of this study was the evaluation of the reservoirs' sanitary conditions, given tha the water is also used for human consumption. 114 samples (4 locations at each lake) were collected in the period from July 1995 to June 1996. We analysed temperature, pH, oxygen saturation, colour and parameters of water mineralization and pollution of natural or human origin.Pathogenic bacteria (Salòmonellae) and opportunistic patjogens such as Pseudomonas aeruginosa and Aeromonas spp. were also investigated. At present, results are not showing particular levels of pollution, and it seems there is no ris…

Application of algae in active biomonitoring of the selected holding reservoirs in swietokrzyskie province

2016

During the years 2014-2015, biomonitoring studies were carried out at three holding reservoirs located in Swietokrzyskie Province (central Poland): Kielce artificial lake, Chancza reservoir and Sielpia reservoir. In sea water algae Palmaria palmata (Linnaeus) Weber & Mohr, exposed in the analysed waters, the increases of concentrations were determined by the atomic absorption spectrometry method (AAS), of the following: Mn, Fe, Cu, Zn, Cd and Pb. Conductivity and pH were also determined in the reservoirs waters. The differences between the increases of heavy metal concentrations in the samples of algae found along the coastline were indicated; they result from different distances from the p…

Occurrence of some heavy metals in waters and bottom sediments in two small dam reservoirs

2008

La spécialisation des productions et les spécialistes: Une introduction

2018

With the emergence of manufacturing based economies, specialised productions take on new dimensions during the Neolithic. Production networks progressively develop during the Neolithic and the Metal Ages and can be characterised according to their scale, how they are organised, the status of producers and the intensification of the trade of manufactured goods. This results on the one hand in mass production and on the other in the creation of highly technical objects on demand within a complex economic system of consumption and exchange. This is not seen as a linear progression but as a diversification of productions, products and know-how, the chronological and social contextualisation of …