Etude comparee de la resistance de trois souches virales en eau de mer et en eau de riviere

The authors made a comparative study of the resistance of three strains of virus, Sabin poliovirus I, Mahoney poliovirus I and réovirus I, in sea-water and in river water, “in vitro” and “in situ” in dialysis bags. The results show the preponderant role of the incubation temperature and the exchanges existing between bags on the resistance of the viral strains. The role of these different factors is discussed.     

L'utilisation de souches de micro-organismes de collection pour l'etude de la biodegradabilite des pesticides

Use of Microbial strains from collection in the study of pesticide biodegradability. 5 different herbicides and 1 metabolite of herbicide were subjected to biodegradation by different microbial strains and simultaneously by soil suspensions.To take account of possible co-metabolisme a supplementary source of carbon was added in the culture media. Results were discussed.     

Etude des variations des populations de coliphages et de bacteries fecales en eau de mer

The viral contamination of sea-water at different depths and in the sediments in the area near the discharge of treated domestic sewage, was investigated. The isolation frequency of viral particles was low: on 19 samples of sea-water, 4 are positive and on 6 samples of sediment, 1 is positive. Viral concentrations were not substantial: they varied from 2,9 to 5,9 Most Probable Number Cytopathic Unit (M.P.N.C.U.) in 500 ml of sea-water or in 500 g of sediment. No homogeneous distribution of viral particles in sea-water was observed.     

Conditions d'acceptation ou de rejet des valeurs obtenues apres denombrement de virus ou bacteries sur milieux de culture solides

Enumeration of viruses or bacteria on solid culture media does not ever give statistically acceptable results. When counting is impossible, we must do it again. For accepting or not the counting, the authors established some probability Tables (95% and 99%) according to microbial densities.     

Utilisation de techniques spectroscopiques pour l'etude de particules atmospheriques produites par des sources ponctuelles

Secondary Ion Mass Spectrometry (SIMS) is used to study atmospheric particle production by an industrial source responsible for the acid precipitation phenomenon. A sampling network has been put in place at Rouyn-Noranda to collect local aerosols with cascade impactors. Aerosols have also been collected in the plume of the most important source of SO₂ in Quebec. Instruments have been developed and constructed to collect these samples. A multi-analytical technique approach permits physico-chemical analysis of individual aerosol: SIMS using a 1 μm ion probe and Scanning Electron Microscopy (SEM) coupled with an X-ray analyzer (EDAX) perform micro-analysis, whereas bulk analysis is provided by a SIMS using a 200 μm Argon ion probe. Devices used for localization of microparticles permit manipulation of samples without damaging them and allow analysis of individual aerosol particles with a SIMS after analysis with SEM-EDAX. Laser Microprobe Mass Analysis (LAMMA) is also possible. Negative and positive mass spectra, obtained with a SIMS-Ar⁺, have been analyzed with a multivariate statistical technique. Relations between these mass spectra and specific conditions existing during sampling have been determined.     

Photochimie et environnement X- evaluation de la toxicite des produits de phototransformation de l'hydroquinone et des chlorophenols en milieu aqueux

A test of acute toxicity on DAPHNIA MAGNA is suggested to evaluate the efficiency of the phototransformation as a route of abiotic degradation. This test is recommended for compounds phototransformed into a complex mixture of products. Hydroquinone, 2-chloro-, 4-chloro-, 2,4-dichloro-, 2,4,6-trichloro- and pentachlorophenol were studied as examples. In any case the phototransformation is an useful depollution technique on condition the irradiation to be completed as far as the ultimate step of phototransformation.     

Microméthode de dosage simultané de l'alcool isopropylique et de son métabolite l'acétone

Simultaneous determination of Isopropyl Alcohol and Acetone prove to be necessary in cases of poisoning by this widely used alcohol. An aluminum capsule containing a sample of blood to be analyzed is introduced into a gas chromatograph equipped with a flameionization detector and a Carbowax 20 M - Chromosorb WHP column. Use of a small blood sample (0.50 μl) and high sensitivity of the method make it a selected procedure in the clinical diagosis of poisoning by Isopropyl Alcohol.     

Etude de l'accumulation du cadmium par une bacterie marine en fonction des conditions de cultures

The influence of different cultural conditions (temperature, salinity, pH, organic matter and cadmium concentration, presence of sulfhydryl groups) on the accumulation of cadmium by a Cd resistent marine bacterium was investigated. The results showed that each of these parameters modify to a certain extent both biomass production and cadmium accumulation. This work emphasizes the need for a higher standardization of toxicity tests to ensure a better reliability of results.     

Influence de la pollution sur divers parametres electriques de l'atmosphere et notamment sur le champ electrique terrestre

We have shown, on the site of LACQ, the modification of atmospheric electric parameters in connection with the fall-outs of polluants for various meteorological conditions. For some of these conditions, it seems possible to predict pollution by plume localization and SO₂ detection on the ground.     

Etude des interactions avec le milieu de composes herbicides analogues du propyzamide en fonction de leur structure: Relation produit-plante

A structure activity relation ship is obtained between phytotoxicity and a combination of steric and hydrophobic parameters. The signification of differents parameters and biological reponse is investigated.     

Nouvelles informations relatives aux variations temporaires de l'activite nitrifiante d'un sol evaluee au laboratoire. incidences d'un apport de matieres organiques

Abstract

The results reported in this paper confirm the seasonal influence on soil nitrifying activity estimated in the laboratory. The variations of this activity depend on different factors: climatic conditions, soil nature, occurence of plants, characteristics of the organic matter added to the soil.

A fresh organic matter (straw, for example) leads to reduced nitrifying activity immediately after its incorporation; its depressive action disappears after a month under laboratory condi‐tions. A decomposed organic matter, as a manure, produces no effect.

This work also shows the seasonal variations of the mineral nitrogen immobilization after addition of a fresh organic matter.     

Using chemical models for evaluating the geochemical confinement capacity of a geological barrier application to the Centre de Stockage de l'Aube (France)

The feasibility of using a chemical reaction-based approach for evaluating and modelling the role of adsorption reactions in determining the geochernical confinement capacity of natural geological barriers is being studied as part of an on-going R & D programme. The confined superficial aquifer underlying the Centre de Stockage de l'Aube facility, a geological barrier for this site, has been used as a case study with the following aims. First, development of a site characterisation protocol and demonstration of its use to determine the principal geochemical characteristics of aquifer materials using batch experiments and to represent the information obtained in terms of a chemical model. The experimental results obtained for Ni²⁺ partitioning as a function of total Ni, pH, total Ca and total solid can be satisfactorily represented in terms of reactions with an ion exchange site and a single amphoteric surface hydroxyl site with ferrihydrite reaction constants. A second objective is the incorporation of the reactions in a coupled geochemistry/transport code, and to verify the applicability of the coupled code predictions for Ni²⁺ mass transfer by comparison with the results obtained during column tracer experiments. The breakthrough curve and equilibrium solid phase Ni loading, predicted by a one-dimensional coupled model for a column tracer experiment, agree closely with observed data.Additional studies are underway to reduce model conditionality, to extend the adsorption model to other analogue cations and anions, to incorporate the effect of natural organic matter and to take into consideration precipitation/dissolution of amorphous Fe surface phases.     

Variations annuelles de l'activite nitrifiante d'un sol evaluee au laboratoire

Abstract

The results of the experiment reported in this paper demonstrate the influence of the soil sampling date on soil nitrifying activity, estimated in the laboratory. Treatment with propamocarb leads to parallel and reduced variations of this activity.     

Etude d'une atmosphere de travail interactions chlore-ethene en atmosphere simulee

The main purpose of this work was to be a study, within a simulated atmosphere, of the chlorine-ethylene interactions in order to define more accurately whether they would lead to the formation of chloroethylene, a carcinogenic substance. We have also aimed at assessing the toxicity of the reaction medium under various concentrations and irradiation and humidity conditions. The presence of chloroethylene has never been detected though its following tri- and tetra-chlorinated homologues have been observed during unirradiated reactions. On the other hand, the sampling method described in this paper and the analysis method we used, i.e. gas chromatography-mass spectroscopy, have revealed the presence of many other substances, some of them being just as toxic, e.g. chloroethanal or 2-chloroethanol obtained under u.v. irradiation. The presence, as well as the formation and disappearance rate of the various reaction products thus obtained, are closely related to operational conditions. We have been able to put forward formation mechanisms for the main quoted compounds.     

Atmospheric BTX and polyaromatic hydrocarbons in Rio de Janeiro, Brazil

Polycyclic aromatic and monoaromatic (benzene, toluene and xylene, or BTX) hydrocarbons were monitored in Rio de Janeiro, Brazil, during the summer of 1998/1999. The levels of these aromatic chemicals decreased with distance from main roads, indicating mobile sources are the main pollutant emitters in this Latin American city. Benzo[ghi]perylene/indeno[1,2,3-cd]pyrene and benzene/toluene ratios corroborate this idea. However, higher benzene/toluene ratios at one of the major access routes into the city suggest pollutant inputs from a nearby refinery. Literature data were reviewed in order to outline differences and similarities among sources and levels of aromatic pollutants in large urban agglomerations worldwide. Concentrations of benzo[a]pyrene and benzene, which are well-known carcinogenic chemicals, were relatively low in Rio de Janeiro. This fact was attributed to specific atmospheric conditions during the tropical summer and differences in vehicle fuel composition.