Evaluation Des Teneurs En Eléments Traces Métalliques (Cadmium Et Plomb) Dans L’eau, Les Sédiments Et Deux Espèces De Poissons Clarias Gariepinus (Burchell, 1822) Et Oreochromis Niloticus (Linné, 1758) Dans Le Pool Malebo (Fleuve Congo), RD Congo

Cette étude a pour objectif d’évaluer les niveaux de contamination en Eléments Traces Métalliques (Cadmium et Plomb) dans l’eau, les sédiments et dans l’organisme de deux espèces de poissons, pélagique (Oreochromis niloticus Linné, 1758) et benthique (Clarias gariepinus Burchell, 1822). Elle a eu lieu de Juillet 2019 à Octobre 2019, dans le Pool Malebo (fleuve Congo/Kinshasa) à Kingabwa, sur deux sites (Baramoto et Mongole). Les analyses des Eléments Traces Métalliques ont été effectuées à l’aide du spectrophotomètre UV-visible. Les teneurs en ETM dans les eaux ont été respectivement de 0,01±0,001 pour le Cd (mg/L) et 0,05±0,03 pour le Pb (mg/L) à Baramoto, et de 0,02±0,01 pour le Cd (mg/L), et 0,01±0,005 pour le Pb (mg/L) à Mongole. Ces teneurs sont supérieures aux seuils recommandés par l’OMS (Cd: 0,003 mg/L ; Pb: 0,01 mg/L). L’analyse des sédiments des deux sites a révélé des teneurs généralement faibles, en dessous des seuils recommandés par le Conseil Canadien des Ministres de l’Environnement (CCME). Par ailleurs, les teneurs de ces deux ETM ont montré une certaine variabilité relative dans les branchies et les muscles de deux espèces étudiées. Ces teneurs dépassent les seuils de recommandation de l’OMS (Cd: 0,05 mg/kg; Pb: 0,2 mg/kg) sur la comestibilité des poissons. L’espèce pélagique, Oreochromis niloticus (Cd: 0,179±0,086 mg/kg; Pb: 0,249±0,117 mg/kg) a montré des teneurs élevées que l’espèce benthique, Clarias gariepinus (Cd: 0,173±0,097 mg/kg; Pb: 0,219±0,096 mg/kg). Des plus, chez les deux espèces, Les branchies (Pb: 0,272±0,075 mg/kg à 0,263±0,055 mg/kg; Cd: 0,219±0,122 mg/kg à 0,208±0,055 mg/kg) concentrent plus d’Eléments Traces que les muscles (Pb: 0,166±0,081 mg/kg à 0,236±0,082 mg/kg; Cd: 0,127±0,085 mg/kg à 0,150±0,063 mg/kg). La consommation régulière de ces poissons pourrait engendrée des effets néfastes à la santé humaine. The objective of this study is to assess the levels of contamination of Metal Trace Elements (Cadmium and Lead) in the water, sediments and in the organism of two species of fish, pelagic (Oreochromis niloticus Linnaeus, 1758) and benthic (Clarias gariepinus Burchell, 1822). It took place from July 2019 to October 2019, in the Pool Malebo (Congo River / Kinshasa) in Kingabwa, on two sites (Baramoto and Mongole). The analyzes of the Metal Trace Elements were carried out using the UV-visible spectrophotometer. The ETM contents in the water were respectively 0.01 ± 0.001 for Cd (mg / L) and 0.05 ± 0.03 for Pb (mg / L) at Baramoto, and 0.02 ± 0 , 01 for Cd (mg / L), and 0.01 ± 0.005 for Pb (mg / L) in Mongolian. These levels are above the thresholds recommended by WHO (Cd: 0.003 mg / L; Pb: 0.01 mg / L). Analysis of the sediments from both sites revealed generally low levels, below the thresholds recommended by the Canadian Council of Ministers of the Environment (CCME). In addition, the contents of these two ETM showed a certain relative variability in the gills and the muscles of two species studied. These levels exceed the WHO recommendation thresholds (Cd: 0.05 mg / kg; Pb: 0.2 mg / kg) on the edibility of fish. The pelagic species, Oreochromis niloticus (Cd: 0.179 ± 0.086 mg / kg; Pb: 0.249 ± 0.117 mg / kg) showed higher levels than the benthic species, Clarias gariepinus (Cd: 0.173 ± 0.097 mg / kg; Pb : 0.219 ± 0.096 mg / kg). In addition, in both species, the gills (Pb: 0.272 ± 0.075 mg / kg to 0.263 ± 0.055 mg / kg; Cd: 0.219 ± 0.122 mg / kg to 0.208 ± 0.055 mg / kg) concentrate more Trace Elements than muscles (Pb: 0.166 ± 0.081 mg / kg to 0.236 ± 0.082 mg / kg; Cd: 0.127 ± 0.085 mg / kg to 0.150 ± 0.063 mg / kg). Regular consumption of these fish could have harmful effects on human health.

Ability of metal trace elements accumulation by Lichens, Xanthoria parietina and Ramalina farinacea, in Megres area (Setif, Algeria)

The accumulating ability of the atmospheric Metal Trace Elements (MTE) of two lichenic species thalli; Xanthoria parietina and Ramalina farinacea were evaluated in the region of Megres. The recorded concentrations of MTE (Fe, Cu, Mn, Cd, and Pb) were determined by atomic absorption spectrophotometry (AASF). The ability to accumulate MTE in X. parietina thalli is considerably greater than that of the fruticulous lichen R. farinacea in all stations studied. The general pattern of the elements accumulated in the thalli of the two species in decreasing order of their concentrations was Fe> Mn> Pb> Cu> Cd. The Fe values are very high in X. parietina thalli with an average of 35237.5 ± 3394.2 mg/kg dry wt. In contrast, the Pb concentrations are high, especially in the southern station of the Megres region. The results showed that X. parietina is a hyper-accumulating species of MTE, compared to R. farinacea. This work highlights the ecological importance of this species as a stable and resistant pioneer in this fragile region.

Development of X-ray fluorescence methods by use of a Mo X-ray tube and their application in the case of biological samples

In the present work two different experimental arrangements, aiming in the X-ray fluorescence analysis of solid and liquid biological samples respectively, were developed and studied both theoretically and experimentally in combination with a Mo anode X-ray tube: The secondary target XRF (STXRF) and the Total Reflection XRF set-up (TXRF). The secondary target XRF irradiation chamber was designed and constructed in our laboratory. Careful choice of the materials combined with the tight geometry used, minimize the presence of interference peaks in the spectrum and offer high intensity of the exciting beam at the sample position. Optimum performance was ensured by means of an extended theoretical and experimental study of various parameters affecting the analytical capabilities of secondary target XRF systems, such as: The choice of secondary target material and the operational conditions of the X-ray tube. The secondary target XRF set-up was applied in the determination of the concentrations of trace elements in a pool blood serum sample. A simple preparation technique, like the freeze-drying process was employed, resulting in detection limits of 15 ng/ml for most metal trace elements and for a 6000 sec measuring time. The accuracy of the whole experimental procedure, examined by internal standardization and by analyzing the reference standard material A-13, was found to be about 4% over the whole atomic number range. For the determination of the mass absorption coefficients, necessary in the quantification step, a modified version of the emission transmission method was employed. Total Reflection X-Ray Fluorescence (TXRF) is a well-established method, mainly applied in the analysis of liquid samples, offering very low detection limits in most of the cases. Direct application of the TXRF method is not so efficient in blood serum analysis, since the high content of the organic matrix increases significantly the background due to Compton scattering. Chemical treatment of the blood serum samples and related preconcentration techniques have been suggested in literature, but they are time consuming and increase the possibility of adding contaminants in the sample. In this work, the applicability of direct TXRF analysis in blood serum samples was examined. The insertion of a Mo filter after the cut-off reflector has been found to improve significantly the peak to background ratio, especially for the elements of interest such as Cu, Zn, Se and Br. The influence of self-absorption phenomena in the quantification procedure was also investigated with respect to the internal standard used and the sample mass analyzed. Precision and accuracy in the analysis was found to be about 4% over the whole atomic number range. Detection limits were in the order of 25ng/ml for most metal trace elements and a measuring time of 3600 sec.

Metal trace elements in mussels in Urubuqueçaba Island, Santos Bay, Brazil

The objective of this work was to verify the existence of bioaccumulation in mussels of the species Perna perna, by determining the concentration of metal trace elements, in Urubuqueçaba Island, Santos Bay, Santos, SP, Brazil. Mussels were collected in natural banks and rocky shores, and sampling took place from April 2010 to June 2011. The concentration of the trace metal elements - aluminum, cadmium, cromium, copper, iron, manganese, nickel, lead, and zinc - was determined according to mussel sex, length, and seasonality classes, in a flame atomic absorption spectrometer. Statistical analyses were applied to the results with the use of the software PAST, with parametric and nonparametric approaches, at 5% probability. In the summer, mussels show the highest concentrations of cadmium, copper, lead, and zinc. Females of P. perna concentrate more copper; for the other elements, there are no significant differences between sexes. The length classes with the highest concentrations are 3.5-5.5 cm for Al and Fe, and 6.5-8.5 cm for Cr.