Etude de la pollution des eaux des oueds Seybouse et Mellah (Région de l'Est Algérien)

L'objet de cette étude est d'expérimenter un protocole de travail base sur des prélèvements de surface et de puits de particuliers en vue d'établir la qualité des eaux et d'assoir des bases de données relatives à la pollution hydrique en Algérie. Les résultats des analyses chimiques montrent pour les deux oueds un facies chimique dominant et caractérise par le chlorure sulfate sodique, en relation avec des rejets industriels, domestiques et le lessivage des formations géologiques. L'établissement du diagramme ammonium-nitrate montre que le rapport NH4+/NO3- diminue d'amont en aval et s'explique par la transformation de l'ammonium en azote au cours de la période d'observation s'étalant de janvier à juin 2007. Des teneurs excessives en PO43- dans l'oued Mellah ont été observées comparativement à l'oued Seybouse, ce qui conduit à une eutrophisation. Les variations de la DB05 et de la DCO évoluent suivant des valeurs acceptables dans les deux oueds. Les teneurs excessives en chlorure (>600 mg/l) dans l'oued Mellah s'expliquent par les rejets domestiques, industriels et au lessivage des formations sédimentaires évaporitiques. La simulation montre que le NH3 et l'oxygène sont en sous-saturation dans les eaux surtout au niveau de l'oued Mellah témoignant ainsi d’une eutrophisation avancéeMots clés: Oued Seybouse - Oued Mellah - Qualité des eaux - Pollution, Eau de surface - Puits – simulation The purpose of this study is to test a working protocol based on sampling from surface and belonging to individual wells to establish water quality and to set a database on the extent of water pollution in Algeria. Chemical analysis results indicate that the dominant chemical compounds are characterized by sodium and chloride-sulfate as a result of domestic and industrial discharges, and geological formations leaching. The construction of ammonium-nitrate diagram shows that the ratio NH4+/NO3-decreases from upstream to downstream and is explained by the conversion of ammonium into nitrogen during the observation period ranging from January to June 2007. Excessive levels of PO43- in the Mellah river were observed compared to the Seybouse, which leads to eutrophication. Changes in DBO5 and DCO evolve following acceptable levels in both rivers. Excessive chloride concentrations (>600 mg/l) in the Mellah river may be explained by domestic waste, industrial and evaporitic formations leaching. The simulation shows that NH3 and oxygen are under-saturation in the water especially in the Mellah river reflecting an advanced eutrophication.Keywords: Seybouse river- Mellah river- Water quality- Pollution- Surface water- Water wells- Simulation.   

The age and origin of groundwater in the Great Western Erg sub-basin of the North-Western Sahara aquifer system: insights from Krechba, central Algeria

Abstract: The North-Western Sahara aquifer system (NWSAS) forms an important transboundary groundwater resource whose properties remain to be fully understood across its whole extent. For example, groundwater flow in the Cretaceous Continental Intercalaire (CI) unit of the NWSAS is well-characterised in the northern part of its range around the Algeria/Tunisia/Libya borders and in the Great Eastern Erg sub-basin immediately to the south. To the southwest, however, the CI of the Great Western Erg sub-basin has been much less studied. The present paper reports hydrogeochemical data from a wellfield in central Algeria which will contribute to a better understanding of this sector of the NWSAS in terms of the age and origin of groundwater within it. Groundwater pumped from five deep boreholes in the CI aquifer overlying the Krechba gas field has been studied using a variety of environmental tracers including hydrochemistry, environmental isotopes, and reactive and noble gases (the latter being reported for the first time for this sub-basin). All the waters were dilute (SEC 460–600 µS/cm), contained detectable O2 (6.3–7.5 mg/L), showed evidence of evaporation (relative enrichment in δ18O), gave late-Pleistocene 14C model ages (13.5–19.3 ka), and yielded lower than present-day noble gas recharge temperatures (14.3–17.6°C). Various lines of evidence suggest that these waters are the product of mixing between water recharged direct to the CI and leakage from the Neogene–Quaternary Erg aquifer. The results support the long-held concept of regional flow from a palaeo-recharge area to the northwest. Finally, while the Krechba gas field (Carboniferous) has been since 2004 the site of a pilot carbon capture and storage (CCS) project, the data revealed no evidence for leakage of fluids (gas or brines) into the overlying CI aquifer at the time of sampling (October 2014)

Simultaneous determination of 4-aminophenol and paracetamol based on CS-Ni nanocomposite-modified screen-printed disposable electrodes

In the present work, chitosan-coated nickel nanoparticles (CS-Ni) were successfully prepared onto screen-printed electrode (SPE) by electrodeposition method with the assistance of an anionic surfactant of sodium dodecyl sulfate (SDS) for the individual and simultaneous sensing of 4-aminophenol (4-AP) and paracetamol (PA). The as-prepared sensor was characterized via scanning electron microscopy, X-ray diffraction, and fourier transform infrared techniques. The electrochemical catalytic behaviors of the 4-AP and PA on the fabricated NiNPs-SDS/CS/SPE electrode were explored using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). The NiNPS-SDS/CS modified screen-printed electrode demonstrated excellent electrocatalytic activity for 4-AP and PA, indicating that nickel microstructures have a high specific surface area, excellent electrical conductivity, and high electrocatalytic activity. The results indicate that CV and DPV could be easily applied to determine 4-AP and PA using the fabricated sensor under optimized conditions. However, CV is preferred for both analysts’ sensing, with the largest linear range from 1 to 500 μM for 4-AP (R2 = 0.999) and 1 μM to 2 mM (R2 = 0.997) for PA, respectively. In terms of sensitivity and detection limit, DPVs response appeared to be a better technique choice, as it revealed the highest sensitivity values of 0.959 µA µM−1 cm−2 for 4-AP and 1.163 µA µM−1 cm−2 for PA, with the lowest detection limits of 0.06 and 0.04 μM for 4-AP and PA (S/N = 3), respectively. With a high recovery rate, good selectivity, excellent reproducibility, and strong anti-interference ability, the modified sensor was successfully applied to the simultaneous detection of 4-AP and PA in pharmaceutical tablets. It is expected to be widely used in actual sample detection