Elektrochemische Oxidation sprengstoffspezifischer Nitroaromaten

Die Kinetik des lichtinduzierten Abbaus von TNT und 16 anderen nitroaromatischen Verbindungen (Nitrotoluene, Nitrobenzene, Nitrotoluidine und Nitrophenole) in wässriger Lösung durch die Photo-Fenton-Reaktion wurde untersucht. Die homogenen Lösungen enthielten Fentons-Reagenz, d.h., Wasserstoffperoxid und Eisen(III)-sulfat oder organische Eisen(III)-Komplexe. Die Transformation der nitroaromatischen Verbindungen durch die Fenton-Reaktion, durch eine Photolyse in Gegenwart von Wasserstoffperoxid oder Eisen(III)-sulfat oder organische Eisen(III)-Komplexen wurde ebenfalls studiert. Im Vergleich zu den anderen Oxidationsprozessen waren die Reaktionsgeschwindigkeiten der Photo-Fenton-Reaktion in der Regel größer. Die Reaktionsgeschwindigkeit der Photo-Fenton-Reaktion wurde in Gegenwart von Eisen(III)-oxalat- oder Eisen(III)-gluconat-Komplexen gesteigert. Die Reaktionsgeschwindigkeit des Abbaus der nitroaromatischen Verbindungen ist Abhängig von der Art und der Anzahl der Substituenten am aromatischen Ring. Die Reaktivität der untersuchten Verbindungen nimmt mit zunehmender Zahl der Nitro-Gruppen am aromatischen Ring ab. Die Methyl-Gruppe der Toluole steigert die Reaktivität. Die folgende Reihenfolge der Reaktivität wurde beobachtet: Nitrotoluidine > Nitrophenole > Nitrotoluene > Nitrobenzene. Diese Reihenfolge kann mit der elektronenanziehenden Kraft der Nitro-Gruppen erklärt werden.The kinetics of the light-induced degradation of TNT and 16 other nitroaromatic compounds (nitrotoluenes, nitrobenzenes, nitrotoluidines and nitrophenols) in aqueous solutions by the photo-Fenton reaction has been investigated. The homogeneous solutions containing Fenton's reagent, i.e., hydrogen peroxide and iron(III)-sulphate or organic iron(III) complexes. Also the transformation of the nitroaromatic compounds by the Fenton reaction, by the photolysis in the presence of hydrogen peroxide or iron(III)-sulphate or organic iron(III) complexes has been studied. Reaction rates were always found to be higher in the photo-Fenton reaction in comparison with the other oxidation processes. The reaction rates of the photo-Fenton reaction is enhanced in the presence of iron(III)-oxalate or -gluconate complexes. The reaction rates of the degradation of the nitroaromatic compounds depend on the kind and number of substituents attached to the aromatic ring. The reactivity of the compounds investigated decreased with increasing numbers of nitro groups on the aromatic ring. The methyl group of the toluenes enhanced their reactivity. The following order of reactivity was observed: nitrotoluidines > nitrophenols > nitrotoluenes > nitrobenzenes. This gradation can be explained with the electron-withdrawing power of the nitro group

A biochemical laboratory manual for species characterization of some tilapiine fishes

This publication is both a manual for the biochemical analysis of several tissues of tilapias and an empirical demonstration of the methods for several species. Given the great and growing importance of tilapia in aquaculture and the importance of knowing the genetic composition of broodstock, the present work pays particular attention to blood-based tests in an effort to determine whether non-destructive sampling of fish tissue is feasible.Stock identification, Genetics, Racial studies, Biochemical analysis, Analytical techniques, Manuals, Ghana, Tilapia, Sarotherodon, Oreochromis

Oxidative stress and immunologic responses following a dietary exposure to PAHs in Mya arenaria

<p>Abstract</p> <p>Background</p> <p>The aim of this research was to investigate oxidative stress and immune responses following a dietary polycyclic aromatic hydrocarbon (PAH) exposure in a marine bioindicator organism, the soft shell clam, <it>Mya arenaria</it>. Immune parameters in hemolymph (haemocyte number, efficiency of phagocytosis and haemocyte activity) and assessment of oxidative stress using catalase (CAT) activity and levels of malondialdehyde (MDA) performed on the digestive gland were estimated as biomarkers in clams fed in mesocosm with PAH contaminated phytoplankton. MDA levels and CAT activities were also measured <it>in situ </it>in organisms sampled in a control site (Metis Beach, Québec, Canada) as well as organisms sampled in a site receiving domestic effluents (Pointe-au-Père, Québec, Canada), to assess effects of abiotic variables related to seasonal variations and mixed contamination on the selected parameters.</p> <p>Results</p> <p>Results on immune parameters suggest that the PAHs may interfere with the maturation and/or differentiation processes of haemocytes. MDA results showed that lipid peroxidation did not occur following the exposure. The levels of CAT activity corresponded to weak antioxidant activity (no significant differences). Recovery was noted for all the immune endpoints at the end of the experiment.</p> <p>Conclusion</p> <p>Results suggest that immune parameters are early biomarkers that can efficiently detect a physiological change during a short term exposure to low concentrations of PAHs. The <it>in situ </it>survey (in the natural environment) suggested that clams from the Pointe-au-Père site did not show any oxidative stress as well as the clams contaminated in mesocosm, probably due to the low concentrations of PAHs used for this study. MDA levels increased however in organisms from Metis Beach, a response probably related to domestic effluents or parasitism.</p