Évolution de la pollution des eaux de l’Oued El Mellah (Djelfa région steppique de l’Algérie)

La steppe Algérienne couvre une superficie de 20 millions d’hectares, en plus du manque des ressources en eaux que connaît ce domaine, vient s’ajouter le phénomène de pollution. La croissance démographique et urbaine importante de la ville de Djelfa accroît les quantités de rejets d’eaux usées dans l’oued El Mellah qui traverse cette ville. A partir d’un suivi saisonnier de la qualité des eaux de cet oued dans cinq stations d’échantillonnages, on a constaté l’ampleur de la pollution organique et minérale qui dépasse les normes. L’effet de dilution lié à la précipitation, diminue la pollution des eaux entre les mois d’octobre et mai.Mots-clés : eau usée, oued, pollution, Djelfa, Algérie

Feasibility of sand filters to wastewater treatment in rural areas in Algeria: experimental study

International audienc

Distribution of Natural Radioactivity, 137Cs, 90Sr, and Plutonium Isotopes in a Water Column and Sediment Core along the Algerian Coast

Concentrations of natural (40K, 210Pb, uranium, and thorium series) and artificial radioelements (137Cs, 90Sr, 239+240Pu) were determined in seawater and sediment samples collected from stations along the Algerian coast. Seawater was collected from the surface to a maximum depth of 2000 m; the sediment cores were sampled from a depth of around 1500 m. This work was carried out in August 2001, in the framework of the Regional African project /7/004 (RAF), by the accomplishment of an oceanographic campaign organized by the International Atomic Energy Agency (IAEA) in collaboration with Commissariat à l'Energie Atomique (COMENA) and L'Institut des Sciences de la Mer et de L'Amenagement du Littoral (ISMAL), on board of the research vessel of M.S. Benyahia of ISMAL. In addition to the record of the conductivity (mS) and temperature (°C) data at each station, seawater samples were treated and preconcentrated on board, those of sediment cores were divided into different layers in order to undergo analyses in the laboratory of radiological impact studies of Algiers. Concentration results were obtained for 137Cs and 90Sr in mBq/L and 239+240Pu in μBq/L in seawater, and also for natural and artificial radionuclides in Bq/kg dry weight in the layers of the sediment cores. The different profiles of 137Cs, 239+240Pu, 90Sr, and 210Pb concentrations against depth were presented to show artificial radioactivity distribution in the water column and sediment core. Concentrations of 137Cs in the sediment core were also used to identify the 137Cs peak in the area of interest

CCR2/CCL2-mediated inflammation protects photoreceptor cells from amyloid-β-induced apoptosis.

Age-related macular degeneration is characterized by the formation of drusen containing amyloid-β (Aβ) and the degeneration of photoreceptors. To explore the largely unknown role of Aβ in the retina, we investigated the effects on photoreceptors of the oligomeric form of Aβ(1-42). Subretinal injection of the Aβ peptide induced misplaced expression of recoverin and synaptophysin in the photoreceptors, oxidative stress in their inner and outer segments, and finally apoptosis. Aβ did not induce cell death in purified photoreceptor cell cultures, but did so in retinal cell cultures, thereby suggesting that the cellular environment plays a role in Aβ-induced photoreceptor apoptosis. Subretinal injection of Aβ was followed by activation and migration of microglial cells and then by photoreceptor apoptosis. Microglial cells phagocytosed rhodopsin-containing debris and Aβ in the subretinal space. Quantitative RT-PCR allowed us to identify a specific gene expression profile associated with the Aβ-induced progression of retinal degeneration and consistent with oxidative stress, inflammation, and an apoptotic program. The gene most highly upregulated in Aβ-injected retinas was that for the chemokine CCL2, and its absence or that of its cognate receptor CCR2 greatly reduced migration of activated microglial cells to the site of retinal injury and profoundly worsened photoreceptor degeneration and disorganization of the retinal pigment epithelium in Aβ-injected retinas. Our study pinpoints the roles of Aβ and of CCL2/CCR2 axis-dependent inflammation in photoreceptor apoptosis