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Sfax, Tunisia

Amorri J.,University of Carthage | Geffroy-Rodier C.,University of Poitiers | Boufahja F.,University of Carthage | Mahmoudi E.,University of Carthage | And 3 more authors.
Environmental Science and Pollution Research | Year: 2011

Introduction: Complex organic compounds found in oil and sediments linked with a particular source (such as algae, bacteria or vascular plants) are defined as biomarkers and are useful dating indicators in organic geochemistry. Methods and results: This paper presents the composition of the organic matter (OM) on marine surface sediments from a degraded Tunisian coast analysed by pyrolysis and gas chromatography-mass spectrometry (GC-MS). High total OM contents (0.3-4.2%) were detected with high levels of saturated linear hydrocarbons. The aliphatic lipids had contributed with up to 11.7% of the total OM, and their distribution had consisted of resolved compounds (n-alkanes and fatty acid (FAs)) and an unresolved complex mixture. Hydrocarbons, primarily n-alkanes, were ranged from 368 to 3,886 μg g-1. The FAs (674-2,568 μg g-1) were dominated by derived primary production, and the short chain FAs (C16 and C18) were the most abundant throughout. The ubiquitous presence of petroleum contamination, mainly from offshore oil exploration, discharge of pollutants from rivers, shipping activities and atmospheric deposition was found in all samples. The Gabès littoral seems to be quite to very polluted near the industrial zone of Ghannouch. The C/H ratio (generally around 5.9), the thermal analysis and GC-MS of n-alkanes and FAs showed that the OM in the studied area was composed of anthropogenic/petrogenic, marine and continental sources. Conclusions: Our study represents an innovative approach to assessing environmental pollution. The evaluation of organic matter by examination of sterols, alkanes and fatty acids allows the identification of source, both anthropogenic and natural. © 2011 Springer-Verlag.

Akrout D.,CNRS Georesources lab | Cobbold P.R.,French National Center for Scientific Research | Ahmadi R.,Laboratoire Eau | Mercier E.,University of Nantes | Montacer M.,CNRS Georesources lab
Marine and Petroleum Geology | Year: 2016

The Gulf of Mexico and the offshore Campos and Santos basins of Brazil provide good examples of sub-salt detachments, by shearing in the presence of overpressure.We have developed new physical models of such situations, including layers of ductile silicone putty, which simulated an evaporite, and fluid overpressure in porous brittle layers. We studied two configurations, in which the maximal overpressure was either beneath a single ductile layer of silicone (simulating salt), or between two such layers of silicone (simulating an evaporite sequence).The results of our analogue modelling showed that detachment faults appeared and persisted at the bases of the ductile layers, even though some ductile deformation occurred simultaneously within these layers. For models where maximal overpressure was between two ductile layers, detachment occurred mainly at the base of the upper silicone layer.On comparing our models with structures in the Gulf of Mexico or offshore Brazil, we find strong similarities, which lead us to suspect that detachment is indeed possible at the base of an evaporite sequence in nature. This conclusion has strong implications, not only for the understanding of petroleum systems, but also for better management of petroleum production in sedimentary basins. © 2016 Elsevier Ltd.

A study carried out in the catchment area of Abiergué in Yaounde (Cameroun) highlighted the sanitary impact due to a rough management of the water resources in the urban areas of the developing countries. The study was undertaken according to a holistic and participative approach strongly anchored in the ÉCOSANTÉ concept. Activities including inquiries in the households, the talks semi-structured with the institutional and non institutional actors involved in water management, bacteriological and parasitologic analyses of water, analyses saddles and the consultation of the registers of health were carried out on this matter on the basis of well defined protocol. It comes out from this study that the water resources in the catchment area of Abiergué (Yaounde-Cameroun) are in the grip of a permanent degradation ensuing from an insufficient sanitation and from an ineffective management and inefficient of solid waste, dependent on a rough management of the water resources. Indeed, the bad governance observed at the level of the water resources is on the base of the scattering of a string of sources of pollution (latrines, heap of wild garbage,⋯) on the whole space of this catchment area, which contribute to distort daily the quality of surface and underground water. Analyses made on some water samples (underground, surface and raw waste water) revealed on this matter fluctuating rates of germs of faecal contamination: faecal coliforms (5 to 9.6 × 103 UFC/100 ml for underground water; 5.025 × 103 to 7.8 × 105 UFC/100 ml for surface water and 62 × 103 to 3 × 106 UFC/100 ml for raw waste water), faecal streptococci: (0 to 7.4 × 103 UFC/100 ml for underground water, 1.1 × 103 to 5.2 × 104 UFC/100 ml for surface water and 8.1 × 103 to 2.2 × 104 UFC/100 ml for raw waste water). Parasitologic analyses made on surface water samples and raw waste water samples allowed to highlight eggs of helminths (0 to 37 eggs/l), cysts of Giardia (1 to 12 cysts/l) and cysts of Entameba histolytica (20 to 62 cysts/l). In this, the emergence of the hydric diseases (amoebiasis intestinal, typhoid,⋯), real public health problems in this area towards statistics recorded in the registers of the hospitals (approximately 34% of the reasons of consultation) finds elements of justification there. The raising awareness of the population coupled with the implementation of the effective local actions strongly soaked with the concepts of Integrated Water Resources Management (IWRM) and Ecohealth are imperative in this context in order to break the infernal cycle of the trilogy including: pollution of the water resources; degradation of the population health; endemicity of poverty. © 2011 ASEES.

Makni J.,Laboratoire Eau | Bouri S.,Laboratoire Eau | Ben Dhia H.,Laboratoire Eau
Arabian Journal of Geosciences | Year: 2013

Given the vital importance of water and energy in desert regions, we undertook a study dealing with the deep reservoirs in Gabes area, which is located in the southeastern part of Tunisia. Geothermal resources are taken from the Intercalary Continental [or Continental Intercalaire (CI)], known as the largest deep aquifer in Tunisia and are used in a number of applications, mainly in agriculture. Previous investigations performed on the thermal waters of this area focused on the genesis of the deep waters with regard to the thermal features of geothermal reservoirs. A more detailed investigation has been carried out, considering both deep and shallow waters. In order to estimate the potential temperatures of deep reservoir in the Gabes area, we developed a synthetic study including chemical geothermometers, multiple mineral equilibrium approach, and other approaches. Chemical types of the thermal waters and effects of mixing between shallow cold waters with deep thermal waters were also discussed. In fact, the application of Na-K-Mg diagram relative to deep geothermal reservoir capitulate estimated temperatures (about 90°C). In addition, the multiple mineral equilibrium approach submits a similar estimated temperature ranging between 65 and 70°C, showing a disequilibrium status which indicates a possibly mixing with surface water. Indeed, wells exploiting the CI aquifer in the south part of the studied area showed the same characteristics, corroborating the reliability of the applied methods. © 2012 Saudi Society for Geosciences.

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