Étude de l'impact des activités touristiques sur la qualité de l'eau et l'organisation des peuplements macrobenthiques au sein des cours d'eau de la Principauté d'Andorre

Le développement considérable de l'activité touristique hivernale et estivale entraîne des perturbations au niveau des principaux cours d'eau andorrans. Il est intéressant d'étudier l'impact de ces perturbations sur des réseaux hydrographiques de haute altitude caractérisés par des conditions du milieu particulières (basse température-forte pente). Les données disponibles concernant la physicochimie et la faune des eaux andorranes sont réduites (PUIG, 1979 ; PEÑA, 1983).Treize stations ont été étudiées dans le cadre de ces travaux.Au cours d'un cycle annuel (automne 1998 à automne 1999), huit prélèvements d'invertébrés benthiques ont été réalisés à chaque station à l'aide d'un filet Surber (vide de maille : 200 µm-surface échantillonnée : 1/ 20e m2).Neuf paramètres physicochimiques (température, pH, conductivité, DCO, DBO5, nitrates, nitrites, ammoniaque, phosphates) ont été mesurés de façon hebdomadaire à chaque station.Le traitement des données physicochimiques par analyses discriminantes révèle l'existence d'un gradient amont-aval de dégradation de la qualité de l'eau. Parallèlement, la qualité de l'eau suit un cycle saisonnier mis en évidence par l'opposition entre campagnes d'été et d'hiver-printemps 1999, d'une part, et campagnes d'automne 1998-1999, d'autre part.L'analyse de la répartition spatiotemporelle de la faune benthique, basée également sur des analyses discriminantes, met en évidence la disparition des taxons polluosensibles dans les stations intermédiaires et aval comme les filtreurs (Simuliidae), les prédateurs (Perlodae, Perlididae, Rhyacophilidae) et les fragmenteurs (Nemouridae, Leuctridae) et l'apparition de nouveaux taxons polluotolérants en aval (Chironomidae, Oligochètes). Ce genre de phénomène a déjà été observé dans d'autres cours d'eau de montagne soumis à des perturbations entraînant l'augmentation de la charge organique (DECAMPS et PUJOL, 1977).Ces taxons polluotolérants comme par exemple, les Oligochètes qui prolifèrent dans la zone aval du cours d'eau principal (Gran Valira) et en aval de l'unique station d'épuration située sur l'Ariège remplacent dans la structure trophique d'autres taxons polluosensibles. Ce phénomène s'observe également au sein d'un même groupe trophique, c'est le cas des prédateurs composés des Perlidae, des Perlodidae et des Rhyacophilidae présents dans les stations de haute altitude et qui disparaissent en aval où ils sont remplacés par les Achètes (Glossiphoniidae).Le calcul de plusieurs indices biologiques d'évaluation de la qualité des eaux (IBGN - BMWP), de richesse et de diversité spécifiques (indices de Shannon et de Margalef), de structure des peuplements (CUMMINS, 1979, 1985) met en évidence la diminution de la richesse et de la diversité spécifiques des stations amont vers les stations aval.L'impact du développement touristique se manifeste à partir des stations de moyenne altitude. Dans ces stations, la pollution est partiellement évacuée, chaque automne, par l'eau de bonne qualité en provenance des zones amont des cours d'eau. Ce phénomène se traduit par une grande variabilité des conditions physicochimiques et de la composition des communautés benthiques. Dans les stations aval, la pollution prend plutôt un caractère chronique suite à la concentration des pollutions en provenance des différentes zones perturbées. La variabilité des conditions du milieu et des assemblages faunistiques est donc moindre.Les résultats obtenus à partir du traitement des données physicochimiques et faunistiques mettent en évidence une dégradation de l'intégrité écologique des cours d'eau (modifications physicochimiques, modifications du peuplement, diminution de la diversité). L'impact des perturbations d'origine anthropique suit un cycle dépendant de la fréquentation touristique. Au cours de ce cycle, alternent deux périodes " critiques " caractérisées par des perturbations hivernales (ski) et estivales (tourisme, randonnées) et une période de " récupération " durant l'automne.Ces travaux ont permis de tester l'hypothèse des perturbations intermédiaires du milieu (CONNELL, 1978 ; RESH, 1988 ; TOWNSEND et al., 1997) et de rechercher les seuils d'intensité des perturbations et/ou l'amplitude de ces perturbations ainsi que leur impact négatif sur la composition faunistique (EDWARD et RYKIEL, 1985 ; PICKETT et al., 1989 ; REICE et al., 1990).The important development of tourism during winter and summer disturb the main Andorran streams. The impact of these disturbances were studied in high altitude streams characterised by particular environmental conditions (e.g. low temperature - steep slope) as little is known about water quality and associated benthic fauna in Andorran streams (PUIG, 1979; PEÑA, 1983).Thirteen sites were seasonally studied during one year, from autumn 1998 to autumn 1999, in each site, eight macroinverbrates samples were coffected using a Surber sampling net (mesh size 200 µm - sampling area : 1/20e m2). In addition, nine physicochemical parameters (temperature - pH - conductivity - DCO - DBO5 - nitrate- nitrite - ammonia - phosphate) were weekly measured in each site during the entire sampfing period.A discriminant analysis performed on the physicochemical data reaveled and upstreamdownstream gradient of the water quality, with highest disturbance in the downstream sites. From a temporal point of view, the water quality follows a seasonal cycle highlighted by the opposition between on the one hand winter-spring and summer 1999, and on the other hand autumn 1998-1999.The spatio-temporal distribution of the benthic fauna, based on the discriminant analysis, highlighted the disappearance of polluo-sensitive taxa in intermediate and downstream sites such as filtering collectors (Simuliidae), predators (Perfidae - Perlodidae - Rhyacophilidae) and shredders (Nemouridae - Leuctridae). In these areas, sensitive taxa were replaced by polluo-tolerant ones such as Chironomidae and Oligocheta. These patterns were already observed in other mountain streams subjected to high organic disturbances (DECANTS et PUJOL, 1977).As a consequence, polluo-tolerant taxa replace polluo-sensitives taxa with similar functionnal status. For example Oligocheta, proliferate in the downstream (Gran Valira), whereas upstream, they were only abundant on a point source pollution site located on the Ariege river. The same phenomenon was also observed for predators: high unpolluted altitude sites were characterised by stoneflies and caddisflies (Perlidae, Perlodidae, Rhyacophilidae) which were replaced downstream by leeches (Glossiphoniidae). As a consequence, the calculation of the several biological indices of water quality (I.B.G.N - B.M.W.Y'), and diversity descriptors (taxa richness - Shannon index - Margalef index), indicate a drastic reduction of the taxa diversity, evenness and water quality from. upstream to downstrearn sites.Disturbances associated with tourism developinent appeared in the medium altitude sites. In these sites, the water quality benefits from the good water quality from the upstream sites during high discharge periods (i.e. in autumn). This phenomena explained the observed temporal variabihty of both physicochemical conditions and benthic fauna structure. In the down-stream sites, the pollution can be considered as chronic and hence, low envirorimental variability was observed. These results show that Andorran stream ecological integrity is low fonn both physicochemical diversity and population assemblages point of views. Moreover, the impact of anthropic disturbances followed an annual cycle according to tourisin. activities with pollution peaks in winter and suminer corresponding respectively to ski resort and hiking tourisin. The only partial recovery period is represented by the autumn high drainage period.From a theoretical point of view, these results allowed to test the intermediate disturbance hypothesis (CONNELL, 1978; RESH, 1988; TOWNSFND et al., 1997) and to search the threshold of resistence/resilience characteristics of a stream ecosystern considering stream. benthic assemblages (EDWARD et RYKIEL, 1985; REICE et al., 1990; PICKETT et al., 1989)

The commitment of The Jordanian Industrial Companies in Applying Environmental Accounting

Accounting ideology is becoming highly concerned with the environmental responsibility. This study diagnoses the importance of environmental accounting principles of all enterprises .Environmental commitment calls for the need to evaluate any project in terms of its contribution to its environmental responsibilities. This study aims at assessing the environmental responsibility unit of Jordan’s Industrial Companies listed at ASE, and how the financial department in each company copes with the environmental aspects. Study results have indicated that all Jordan’s Industrial Companies are in general committed towards environmental accounting and they keep pace to the developments in this field. Results also revealed that environmental accounting function in industrial corporations keeps pace with the developments in environmental accounting. Key Words: Environmental Accounting, Hypothesis Testing, Validity, Reliability JEL Codes:  Q56, C12 ,C520,Q26

Un-reduction

This paper provides a full geometric development of a new technique called un-reduction, for dealing with dynamics and optimal control problems posed on spaces that are unwieldy for numerical implementation. The technique, which was originally concieved for an application to image dynamics, uses Lagrangian reduction by symmetry in reverse. A deeper understanding of un-reduction leads to new developments in image matching which serve to illustrate the mathematical power of the technique.Comment: 25 pages, revised versio

Sensitivity and identifiability of hydraulic and geophysical parameters from streaming potential signals in unsaturated porous media

Fluid flow in a charged porous medium generates electric potentials called streaming potential (SP). The SP signal is related to both hydraulic and electrical properties of the soil. In this work, global sensitivity analysis (GSA) and parameter estimation procedures are performed to assess the influence of hydraulic and geophysical parameters on the SP signals and to investigate the identifiability of these parameters from SP measurements. Both procedures are applied to a synthetic column experiment involving a falling head infiltration phase followed by a drainage phase.GSA is used through variance-based sensitivity indices, calculated using sparse polynomial chaos expansion (PCE). To allow high PCE orders, we use an efficient sparse PCE algorithm which selects the best sparse PCE from a given data set using the Kashyap information criterion (KIC). Parameter identifiability is performed using two approaches: the Bayesian approach based on the Markov chain Monte Carlo (MCMC) method and the first-order approximation (FOA) approach based on the Levenberg–Marquardt algorithm. The comparison between both approaches allows us to check whether FOA can provide a reliable estimation of parameters and associated uncertainties for the highly nonlinear hydrogeophysical problem investigated.GSA results show that in short time periods, the saturated hydraulic conductivity (Ks) and the voltage coupling coefficient at saturation Csat are the most influential parameters, whereas in long time periods, the residual water content (θs), the Mualem–van Genuchten parameter n and the Archie saturation exponent na become influential, with strong interactions between them. The Mualem–van Genuchten parameter α has a very weak influence on the SP signals during the whole experiment.Results of parameter estimation show that although the studied problem is highly nonlinear, when several SP data collected at different altitudes inside the column are used to calibrate the model, all hydraulic (Ks, θs, α, n) and geophysical parameters (na, Csat) can be reasonably estimated from the SP measurements. Further, in this case, the FOA approach provides accurate estimations of both mean parameter values and uncertainty regions. Conversely, when the number of SP measurements used for the calibration is strongly reduced, the FOA approach yields accurate mean parameter values (in agreement with MCMC results) but inaccurate and even unphysical confidence intervals for parameters with large uncertainty regions.</p

Should We Learn Probabilistic Models for Model Checking? A New Approach and An Empirical Study

Many automated system analysis techniques (e.g., model checking, model-based testing) rely on first obtaining a model of the system under analysis. System modeling is often done manually, which is often considered as a hindrance to adopt model-based system analysis and development techniques. To overcome this problem, researchers have proposed to automatically "learn" models based on sample system executions and shown that the learned models can be useful sometimes. There are however many questions to be answered. For instance, how much shall we generalize from the observed samples and how fast would learning converge? Or, would the analysis result based on the learned model be more accurate than the estimation we could have obtained by sampling many system executions within the same amount of time? In this work, we investigate existing algorithms for learning probabilistic models for model checking, propose an evolution-based approach for better controlling the degree of generalization and conduct an empirical study in order to answer the questions. One of our findings is that the effectiveness of learning may sometimes be limited.Comment: 15 pages, plus 2 reference pages, accepted by FASE 2017 in ETAP

Bilateral stellate neuroretinitis revealing a pheochromocytoma

Neuroretinitis (NR) is an inflammatory disorder characterized by optic disc  edema and subsequent formation of a macular star. We present a case of a 33 year old woman patient admitted for a progressive bilateral visual loss since two weeks. Fundus examination showed bilateral stellate neuroretinitis. Physical examination revealed a malignant hypertension of 210/150mmHg. Magnetic resonance imaging identified a left suprarenal mass, whereas urinary catecholamine level was abnormally high which supported a diagnosis of pheochromocytoma.The patient underwent a laparoscopic left suprarenal adrenalectomy after successful control of blood pressure. histopathologic examination confirmed the diagnosis of pheochromocytoma. Visual acuity was restored and the retinal alterations disappeared 7 months after surgery

Isocyanurate transformation induced healing of isocyanurate–oxazolidone polymers

Isocyanurate–oxazolidone (ISOX) polymers have been reported as a novel, intrinsically self‐healable thermoset, and their healing mechanism under the effect of nucleophiles, such as tertiary amines and pyridines during polymerization, is thoroughly investigated in this study. This work provides evidence that the healing behavior of the polymers results part from the transformation of isocyanurate to oxazolidone on the fracture surfaces of the ISOX polymers at elevated temperatures. The isocyanurate transformation is characterized by chemical composition of the ISOX polymers before and after a predetermined healing procedure, through a combination characterization of Fourier transform infrared spectroscopy and carbon nuclear magnetic resonance spectroscopy. From the chemical composition of the ISOX polymers, an increased oxazolidone fraction is observed after the healing event, which verifies the hypothesized healing mechanism. By correlating the change in oxazolidone fraction in the polymers during the healing event, with the corresponding healing performance of the polymers, healing efficiencies of the polymers are shown to be inversely proportional to the ratio of oxazolidone to isocyanurate in the polymers. The transformation to oxazolidone is also shown to be dependent on two variables, nucleophilicity of the polymerization catalyst and duration of the postcure. The isocyanate and epoxide polymerization mechanism in the presence of nucleophiles is also investigated to explain the effect of the catalyst nucleophilicity on the chemical composition as well as the healing performance of the ISOX polymers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48698.Isocyanurate‐to‐oxazolidone transformation within the polymers for healing.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154270/1/app48695-sup-0001-FigureS1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154270/2/app48698_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154270/3/app48698.pd