Fresh water distribution problematic in Nouakchott

Because of its geographical location, Mauritania is characterized by an arid climate. The water resources are thus limited. The annual average rainfall calculated by M.Yeslem [1] over a 60-years period (1931-1991) is 112 mm. Nouakchott, the Mauritanian capital, knew an exceptional growth of the population, carrying it to more than 700 000 inhabitants in the year 2005 [2]. These brisk demographic trends generated a fast expansion of occupied space and a strong pressure on the social equipments and basic infrastructures and in particular for drinking water. Balloffet E.[3] and Seureca A.[4] indicate that the needs of the population of Nouakchott for drinking water, supplied from underground lake of Idini, increased exponentially the last years, in spite of the fragility of the system for which overexploitation could be prejudicial with the resources. This situation was accentuated by the lack of planning and of a framework of urban regulation. In these particular circumstances, the inhabitants of the town of Nouakchott suffer from all problems related to Water resource availability and quality. This study, carried out over a representative sample of Nouakchott's population coming from two poor districts and a rich one, shows that the rate of access to distribution network, to the sanitation network and accessibility to water are very low for the two poor districts of El Mina and Sebkha. 22%, 4% and 35% of the population had access to the above networks. These meduim rates, are due to households in the district of Tevragh-Zeina (a rich area). In addition, this work shows that the vulnerability of the distributed water is big because of the non generalization of the supplying network. In fact, the results of our physico-chemical and bacteriological analyses/tests carried out on site, in different points of the distribution channel, show that the physico-chemical characteristics of the water conform to the World Health Organization (WHO)'s norms. However, the terminal fountains were found to be contaminated with total and fecal coliforms.This work, based on laboratory diagnosis and analyses results, can be an important prerequisite for the installation of an environment and public health management system associated with the quality of the distributed water in Nouakchott.Because of its geographical location, Mauritania is characterized by an arid climate. The water resources are thus limited. The annual average rainfall calculated by M.Yeslem [1] over a 60-years period (1931-1991) is 112 mm. Nouakchott, the Mauritanian capital, knew an exceptional growth of the population, carrying it to more than 700 000 inhabitants in the year 2005 [2]. These brisk demographic trends generated a fast expansion of occupied space and a strong pressure on the social equipments and basic infrastructures and in particular for drinking water. Balloffet E.[3] and Seureca A.[4] indicate that the needs of the population of Nouakchott for drinking water, supplied from underground lake of Idini, increased exponentially the last years, in spite of the fragility of the system for which overexploitation could be prejudicial with the resources. This situation was accentuated by the lack of planning and of a framework of urban regulation. In these particular circumstances, the inhabitants of the town of Nouakchott suffer from all problems related to Water resource availability and quality. This study, carried out over a representative sample of Nouakchott's population coming from two poor districts and a rich one, shows that the rate of access to distribution network, to the sanitation network and accessibility to water are very low for the two poor districts of El Mina and Sebkha. 22%, 4% and 35% of the population had access to the above networks. These meduim rates, are due to households in the district of Tevragh-Zeina (a rich area). In addition, this work shows that the vulnerability of the distributed water is big because of the non generalization of the supplying network. In fact, the results of our physico-chemical and bacteriological analyses/tests carried out on site, in different points of the distribution channel, show that the physico-chemical characteristics of the water conform to the World Health Organization (WHO)'s norms. However, the terminal fountains were found to be contaminated with total and fecal coliforms.This work, based on laboratory diagnosis and analyses results, can be an important prerequisite for the installation of an environment and public health management system associated with the quality of the distributed water in Nouakchott

Evolution of the fresh water distribution in Nouakchott after the commissioning of the Aftout Es Saheli project

Mauritania is characterized by an arid climate with limited water resources. Nouakchott has experienced tremendous growth, from a population of several hundred people in 1960 to over 700,000 in 2005 according to the National Statistics Office, this growth has generated abnormal pressure on core infrastructure, particularly for drinking water and wastewater management. The water needs of the population of Nouakchott were exclusively met by the excessive exploitation of Idini aquifer’s well field. In late 2010, Mauritania began operating the Aftout Es Saheli project supplying the city with water pumped from the Senegal River. The aim of this paper is to present the evolution of the water situation in the city before and after the Aftout Es Saheli project, and to recommend ways to improve the management of this situation, especially in the peripheral neighborhoods. Our study focused on the water’s availability and physico-chemical and bacteriological qualities in both poor neighborhoods supplied by a high-risk informal distribution system and affluent neighborhoods supplied by the network. In this context, we note that, despite the dilapidated distribution system, the start-up of Aftout Es Saheli and the progressive eradication of the informal system have significantly improved the covering of the population’s water needs with an improving water quality.Mauritania is characterized by an arid climate with limited water resources. Nouakchott has experienced tremendous growth, from a population of several hundred people in 1960 to over 700,000 in 2005 according to the National Statistics Office, this growth has generated abnormal pressure on core infrastructure, particularly for drinking water and wastewater management. The water needs of the population of Nouakchott were exclusively met by the excessive exploitation of Idini aquifer’s well field. In late 2010, Mauritania began operating the Aftout Es Saheli project supplying the city with water pumped from the Senegal River. The aim of this paper is to present the evolution of the water situation in the city before and after the Aftout Es Saheli project, and to recommend ways to improve the management of this situation, especially in the peripheral neighborhoods. Our study focused on the water’s availability and physico-chemical and bacteriological qualities in both poor neighborhoods supplied by a high-risk informal distribution system and affluent neighborhoods supplied by the network. In this context, we note that, despite the dilapidated distribution system, the start-up of Aftout Es Saheli and the progressive eradication of the informal system have significantly improved the covering of the population’s water needs with an improving water quality

Fresh water distribution problematic in Nouakchott

Because of its geographical location, Mauritania is characterized by an arid climate. The water resources are thus limited. The annual average rainfall calculated by M.Yeslem [1] over a 60-years period (1931-1991) is 112 mm. Nouakchott, the Mauritanian capital, knew an exceptional growth of the population, carrying it to more than 700 000 inhabitants in the year 2005 [2]. These brisk demographic trends generated a fast expansion of occupied space and a strong pressure on the social equipments and basic infrastructures and in particular for drinking water. Balloffet E.[3] and Seureca A.[4] indicate that the needs of the population of Nouakchott for drinking water, supplied from underground lake of Idini, increased exponentially the last years, in spite of the fragility of the system for which overexploitation could be prejudicial with the resources. This situation was accentuated by the lack of planning and of a framework of urban regulation. In these particular circumstances, the inhabitants of the town of Nouakchott suffer from all problems related to Water resource availability and quality. This study, carried out over a representative sample of Nouakchott's population coming from two poor districts and a rich one, shows that the rate of access to distribution network, to the sanitation network and accessibility to water are very low for the two poor districts of El Mina and Sebkha. 22%, 4% and 35% of the population had access to the above networks. These meduim rates, are due to households in the district of Tevragh-Zeina (a rich area). In addition, this work shows that the vulnerability of the distributed water is big because of the non generalization of the supplying network. In fact, the results of our physico-chemical and bacteriological analyses/tests carried out on site, in different points of the distribution channel, show that the physico-chemical characteristics of the water conform to the World Health Organization (WHO)'s norms. However, the terminal fountains were found to be contaminated with total and fecal coliforms. This work, based on laboratory diagnosis and analyses results, can be an important prerequisite for the installation of an environment and public health management system associated with the quality of the distributed water in Nouakchott.French Cooperation and the Ministry of Higher Education in Mauritani

Betaproteobacteria dominance and diversity shifts in the bacterial community of a PAH-contaminated soil exposed to phenanthrene.

International audienceIn this study, the PAH-degrading bacteria of a constructed wetland collecting road runoff has been studied through DNA stable isotope probing. Microcosms were spiked with (13)C-phenanthrene at 34 or 337 ppm, and bacterial diversity was monitored over a 14-day period. At 337 ppm, PAH degraders became dominated after 5 days by Betaproteobacteria, including novel Acidovorax, Rhodoferax and Hydrogenophaga members, and unknown bacteria related to Rhodocyclaceae. The prevalence of Betaproteobacteria was further demonstrated by phylum-specific quantitative PCR, and was correlated with a burst of phenanthrene mineralization. Striking shifts in the population of degraders were observed after most of the phenanthrene had been removed. Soil exposed to 34 ppm phenanthrene showed a similar population of degraders, albeit only after 14 days. Results demonstrate that specific Betaproteobacteria are involved in the main response to soil PAH contamination, and illustrate the potential of SIP approaches to investigate PAH biodegradation in soil

The faint young Sun problem

For more than four decades, scientists have been trying to find an answer to one of the most fundamental questions in paleoclimatology, the `faint young Sun problem'. For the early Earth, models of stellar evolution predict a solar energy input to the climate system which is about 25% lower than today. This would result in a completely frozen world over the first two billion years in the history of our planet, if all other parameters controlling Earth's climate had been the same. Yet there is ample evidence for the presence of liquid surface water and even life in the Archean (3.8 to 2.5 billion years before present), so some effect (or effects) must have been compensating for the faint young Sun. A wide range of possible solutions have been suggested and explored during the last four decades, with most studies focusing on higher concentrations of atmospheric greenhouse gases like carbon dioxide, methane or ammonia. All of these solutions present considerable difficulties, however, so the faint young Sun problem cannot be regarded as solved. Here I review research on the subject, including the latest suggestions for solutions of the faint young Sun problem and recent geochemical constraints on the composition of Earth's early atmosphere. Furthermore, I will outline the most promising directions for future research. In particular I would argue that both improved geochemical constraints on the state of the Archean climate system and numerical experiments with state-of-the-art climate models are required to finally assess what kept the oceans on the Archean Earth from freezing over completely.Comment: 32 pages, 8 figures. Invited review paper accepted for publication in Reviews of Geophysic

The Future of Agent-Based Modeling

In this paper, I elaborate on the role of agent-based (AB) modeling for macroeconomic research. My main tenet is that the full potential of the AB approach has not been realized yet. This potential lies in the modular nature of the models, which is bought by abandoning the straitjacket of rational expectations and embracing an evolutionary perspective. I envisage the foundation of a Modular Macroeconomic Science, where new models with heterogeneous interacting agents, endowed with partial information and limited computational ability, can be created by recombining and extending existing models in a unified computational framework

Immune Response and Mitochondrial Metabolism Are Commonly Deregulated in DMD and Aging Skeletal Muscle

Duchenne Muscular Dystrophy (DMD) is a complex process involving multiple pathways downstream of the primary genetic insult leading to fatal muscle degeneration. Aging muscle is a multifactorial neuromuscular process characterized by impaired muscle regeneration leading to progressive atrophy. We hypothesized that these chronic atrophying situations may share specific myogenic adaptative responses at transcriptional level according to tissue remodeling. Muscle biopsies from four young DMD and four AGED subjects were referred to a group of seven muscle biopsies from young subjects without any neuromuscular disorder and explored through a dedicated expression microarray. We identified 528 differentially expressed genes (out of 2,745 analyzed), of which 328 could be validated by an exhaustive meta-analysis of public microarray datasets referring to DMD and Aging in skeletal muscle. Among the 328 validated co-expressed genes, 50% had the same expression profile in both groups and corresponded to immune/fibrosis responses and mitochondrial metabolism. Generalizing these observed meta-signatures with large compendia of public datasets reinforced our results as they could be also identified in other pathological processes and in diverse physiological conditions. Focusing on the common gene signatures in these two atrophying conditions, we observed enrichment in motifs for candidate transcription factors that may coordinate either the immune/fibrosis responses (ETS1, IRF1, NF1) or the mitochondrial metabolism (ESRRA). Deregulation in their expression could be responsible, at least in part, for the same transcriptome changes initiating the chronic muscle atrophy. This study suggests that distinct pathophysiological processes may share common gene responses and pathways related to specific transcription factors

Real-time Monitoring for the Next Core-Collapse Supernova in JUNO

Core-collapse supernova (CCSN) is one of the most energetic astrophysical events in the Universe. The early and prompt detection of neutrinos before (pre-SN) and during the SN burst is a unique opportunity to realize the multi-messenger observation of the CCSN events. In this work, we describe the monitoring concept and present the sensitivity of the system to the pre-SN and SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is a 20 kton liquid scintillator detector under construction in South China. The real-time monitoring system is designed with both the prompt monitors on the electronic board and online monitors at the data acquisition stage, in order to ensure both the alert speed and alert coverage of progenitor stars. By assuming a false alert rate of 1 per year, this monitoring system can be sensitive to the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos up to about 370 (360) kpc for a progenitor mass of 30$M_{\odot}$ for the case of normal (inverted) mass ordering. The pointing ability of the CCSN is evaluated by using the accumulated event anisotropy of the inverse beta decay interactions from pre-SN or SN neutrinos, which, along with the early alert, can play important roles for the followup multi-messenger observations of the next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure

Les radeaux de végétation de la retenue de Petit-Saut (Guyane)

Les retenues artificielles de milieux tropicaux sont la proie, les premières années de leur existence, d'un développement excessif de plantes aquatiques flottantes qui peuvent créer des nuisances et renforcer certains problèmes d'exploitation. La retenue de Petit-Saut présentait un risque élevé d'apparition de jacinthes d'eau (Eichhornia crassipes) car cette plante est représentée sur le littoral guyanais. Le suivi de la végétation effectué dès la mise en eau n'a mis en évidence que l'apparition de radeaux portant essentiellement des hélophytes (Ptéridophytes, Poacés et Cypéracés) et hydrophytes. L'évolution de la composition floristique des radeaux montre une dominante d'espèces colonisatrices typiques des savanes de Guyane. II est remarquable de noter l'abscence de macrophytes flottantes et la prépondérance d'hélophytes nécessitant un support de fixation. Ces végétaux montrent une grande capacité de croissance que compensent en grande partie les processus de décomposition mesurés par différentes voies au sein des radeaux (pertes de biomasse de différents supports végétaux présentant un k moyen de 0,0075 jour-1. Les mesures effectuées in situ mettent en évidence des cinétiques de décomposition traduisant la dominante cellulosique du matériel végétal. L'excès de matière en décomposition des radeaux, placée au sein de la couche oxygénée de surface de la retenue se traduit par des caractéristiques élevées de réduction chimique auxquelles les hélophytes peuvent résister par des adaptations physiologiques propres à ces plantes de marais

Développement du système de qualité environnementale et sanitaire de la distribution de l'eau potable à Nouakchott (Mauritanie)

Nouakchott, capitale de la Mauritanie, a connu une évolution démographique brutale qui a engendré une expansion rapide de I'espace occupé et une forte pression sur les infrastructures de base et particulièrement sur I'eau potable. Dans notre travail de recherche, nous décrivons : 1- Un état des lieux de la quantité et de la qualité des eaux distribuées à Nouakchott. 2- Les facteurs accentuant la vulnérabilité de cette eau tels que le manque d'extension du réseau d'approvisionnement : - qui limite particulièrement la ressource au niveau des quartiers périphériques et qui est accentuée par une faiblesse de pression du réseau, -qui conduit à la contamination des bornes fontaines (indicateurs bactériens de contamination par méthode enzymatique rapide). Les recherches ont été effectuées sur le site des points de distribution et une enquête a été réalisée au niveau des quartiers sélectionnés. 3- Les facteurs favorables à I'évolution des risques de contamination des eaux et à la propagation de maladies d'origine hydrique, tels que le manque de généralisation du réseau d'assainissement et I'utilisation de moyens individuels d'assainissement. Ce travail conduit à I'élaboration et à la proposition d'un système de management de la qualité de distribution de l'eau dans cette ville impliquant les opérateurs de distribution et les pouvoirs publics. L'approche originale comporte une évaluation de I'amélioration de la qualité du système de distribution, liée à une approche HACCP qui doit permettre, par des mesures structurelles à la création d'organismes appropriés, à une optimisation de la ressource et de sa qualité en étroite collaboration avec les demandes des populations. Il s'agit donc d'une démarche pratique basée sur une réflexion théorique approfondie qui a été rarement entreprise dans le cadre d'une grande ville africaine confrontée au problème crucial de l'eau potable et à I'utilisation durable de ses ressources.Nouakchott, the Mauritanian capital, has an exceptional growth of the population, these brutal demographic trends generated a fast expansion of occupied space and a strong pressure on the social equipments and basic infrastructures, in particular for drinking water. In our work we present : 1st An inventory of features of the quantity (resources) and quality of fresh waters distributed in Nouakchott ; 2nd The factors increasing the vulnerability of the water such as :the lack of generalization of the network of provisioning : - which particularly limits the water resource for peripheral districts and this is accentuated by the weakness of pressure of the network, -which leads to the contamination of terminal fountains (determined by bacterial enzymatic methods in water as total coliforms and faecal indicators) according to analyses carried out on various points of distribution and inquiries made in the targeted areas of our study. -3rd Factors suitable for the evolution of the risks of contamination of water and for reduction of propagation of epidemiologic diseases as cholera or other waterborne diseases, due to the lack of generalization of the network for treatment in the city and the use of individual means of treatment (domestic latrines, septic tanks...). This work carried out the development and proposal of a system of environmental management and health quality improvement of distribution of water in this city involving the different operators of the network and the public authorities. The original approach of this work brings a better quality of distribution network, linked to a HACPP development which allows to optimise the resource usage and the quality of water, by structural measures and increasing of ad hoc structures. In fact, this work gives practical and theoretical advance. This approach has scarcely been used for such large towns in Africa, and brings a method for sustainable resources using.CHAMBERY -BU Bourget (730512101) / SudocSudocFranceF