Los checos frente a la crisis europea

¿Es la República Checa euroflemática o eurobelicista? En un contexto de larga duración histórica, en este ARI se explican la actitud y percepción del presidente Klaus hacia la UE y la Constitución, muy diferente de la de su antecesor Václav Havel. Se dan a conocer a los negociadores checos del Tratado Constitucional, se intenta clarificar la contradictoria posición del Gobierno checo en Europa, se observa la visión de los partidos de la oposición y, finalmente, se define la actitud de la opinión pública checa frente a la UE: ¿euroflemática o eurobelicista

Photodégradation du monuron en systèmes homogène et hétérogène en présence de fer et/ou de TiO2 (comparaison et complémentarité)

CLERMONT FD-BCIU Sci.et Tech. (630142101) / SudocSudocFranceF

Development of mutagenicity during degradation of N-nitrosamines by advanced oxidation processes

Development of mutagenicity of five N-nitrosamines (N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosodi-n-propylamine (NDPA), N-nitrosopyrrolidine (NPYR) and N-nitrosodiphenylamine (NDPhA)) was investigated during oxidative processes involving UV-photolysis, ozone and OH radicals. The mutagenicity was detected by the Ames test with 3 different strains, TA98, TAMix and YG7108, a strain which is sensitive for N-nitrosamines, in presence and absence of metabolic activation (S9). UV photolysis of mutagenic N-nitrosamines (NDMA, NDEA, NDPA and NPYR) leads to the removal of their specific mutagenic activity as detected in YG7108 in the presence of S9. A formation of mutagens during UV photolysis was detected only in case of NDPhA in the strain TA98. Oxidation products of NDMA, NDEA and NDPhA did not show any significant mutagenicity in the strains used, whereas oxidation of NDPA and NPYR by hydroxyl radicals seems to lead to the formation of direct mutagens (mutagenic in the absence of S9) in YG7108 and TAMix. Oxidation by hydroxyl radicals of N-nitrosamines with chains longer than ethyl can mimic metabolic activation of N-nitrosamines in vivo

Photoinduced reduction of chromium(VI) by iron aminopolycarboxylate complex (FeNTA)

International audienceChromium(VI) reduction photoinduced by iron(III) nitrilotriacetate (FeNTA) was investigated under monochromatic excitation. 313 nm was used as the irradiation wavelength in order to minimize the absorption of the light by chromium(VI): 91% of the photons were absorbed by FeNTA at pH = 7.0. Quantum yields of FeNTA and chromium(VI) disappearance and iron(II) formation were measured at pH 2.0, 4.0 and 7.0. In all the cases, chromium(VI) reduction follows first order kinetics with maximum efficiency at pH 2.0. The observed rate constant is proportional to FeNTA concentrations up to a maximum of 6.0 x 10(-4) mol L-1. The effect of oxygen was also investigated. If there is no large pH effect and no effect of oxygen on the quantum yields of chromium(VI) and FeNTA disappearance, the pH strongly influences the nature of the reduced chromium species. At pH 2.0, only chromium(III) was detected, whereas at pH 4.0 and 7.0 no chromium(III) resulting from chromium(VI) reduction was observed. Chromium(V) is supposed to be formed and stabilized by the chelating groups of NTA or NTA photoproducts

Effect of iron speciation on the photodegradation of Monuron in combined photocatalytic systems with immobilized or suspended TiO2

International audiencePhotodegradation kinetics of Monuron (3-(4-chlorophenyl)-1,1-dimethylurea) in photoreactor with immobilized and suspended TiO2 photocatalyst were studied. The effect of addition of ferric or ferrous perchlorate was investigated. Whatever the concentration of Fe(III/II) added there is no significant negative effect on the photodegradation rate of pollutants. On the contrary, depending on speciation and concentration of iron salts, slight or marked acceleration of the photodegradation kinetics was observed. This positive influence was more pronounced in the case of TiO2 suspensions than for TiO2 layers. Fe(III) was generally more effective than Fe(II)

Evolution of algal toxicity during (photo)oxidative degradation of diuron

In the aquatic environment and in engineered water treatment systems, organic contaminants can undergo oxidative and photochemical transformations. For an overall risk assessment, the toxicity of the resulting transformation products has to be investigated. In this study, the toxicity of degradation products of diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea) formed during its degradation by four (photo)oxidative processes (direct phototransformation, triplet-induced photosensitized oxidation, oxidation by hydroxyl radicals and ozone) was investigated in buffered aqueous solution. The toxicity was evaluated using the combined algae test with Pseudokirchneriella subcapitata that determines both, specific inhibition of photosynthesis and inhibition of the growth rate. The comparison between evolution of toxicity and degradation kinetics indicated that the toxicity during all studied processes was caused predominantly by diuron whereas the formation of degradation products did not contribute to the mixture toxicity. This implies that, if any more toxic transformation products than diuron were formed, their concentration was not sufficiently high to affect the mixture toxicity, which was dominated by the parent compound diuron. On this account, no further studies on identification of degradation products and their toxicity are needed. This study presents an example of a systematic and simple first tier method to assess the toxicity of degradation products

Removal of the antiviral agent oseltamivir and its biological activity by oxidative processes

The antiviral agent oseltamivir acid (OA, the active metabolite of Tamiflu) may occur at high concentrations in wastewater during pandemic influenza events. To eliminate OA and its antiviral activity from wastewater, ozonation and advanced oxidation processes were investigated. For circumneutral pH, kinetic measurements yielded second-order rate constants of 1.7 +/- 0.1 x 10(5) and 4.7 +/- 0.2 x 10(9) M-1 s(-1) for the reaction of OA with ozone and hydroxyl radical, respectively. During the degradation of OA by both oxidants, the antiviral activity of the treated aqueous solutions was measured by inhibition of neuraminidase activity of two different viral strains. A transient, moderate (two-fold) increase in antiviral activity was observed in solutions treated up to a level of 50% OA transformation, while for higher degrees of transformation the activity corresponded to that caused exclusively by OA. OA was efficiently removed by ozonation in a wastewater treatment plant effluent, suggesting that ozonation can be applied to remove OA from wastewater. (C) 2011 Elsevier Ltd. All rights reserved

Novel test procedure to evaluate the treatability of wastewater with ozone

Organic micropollutants such as pharmaceuticals, estrogens or pesticides enter the environment continuously through the effluent of municipal wastewater treatment plants (WWTPs). Enhanced treatment of wastewater (WW) by ozone (O-3) is probably one of the simplest measures for abatement of organic micropollutants to avoid their discharge to the aquatic environment. During zonation most organic micropollutants present in treated WW are oxidized either by a direct reaction with O-3 or by secondarily formed hydroxyl radicals ((OH)-O-center dot). However, undesired oxidation by-products from the oxidative transformation of matrix components can also be formed. A modular laboratory decision tool based on the findings of previous investigations is presented to test the feasibility of zonation as an option to upgrade specific WWTPs. These modules consist of investigations to assess (i) the matrix effects on ozone stability, (ii) the efficiency of micropollutant removal, (iii) the oxidation by-product formation, as well as (iv) bioassays to measure specific and unspecific toxicity of the treated WWs. Matrix effects on ozone stability (quantified as O-3 and (OH)-O-center dot exposures) can give first indications on the suitability of an ozonation step. Ozonation of WWs yielding O-3 and (OH)-O-center dot exposures and micropollutant abatement similar to reference values evoked a significant improvement of the water quality as indicated by a broad range of bioassays. Irregular behavior of the ozonation points towards unknown compounds, possibly leading to the formation of undesired degradation products. It has been observed that in such WWs ozonation partly enhanced toxicity. In summary, the presented tiered laboratory test procedure represents a relatively cheap and straight-forward methodology to evaluate the feasibility of ozonation to upgrade specific WWTPs for micropollutant removal based on chemical and biological measurements. (C) 2015 Elsevier Ltd. All rights reserved

Evaluation of MnO2 bed filter for the removal of pharmaceutical compounds

International audienc