Predictions of nitrate diffusion in sediment using horizontal attenuated total reflection (HATR) by Fourier transform infrared (FTIR) spectrometry

Using a novel and simple method based on horizontal attenuated total reflection (HATR) by Fourier transform infrared (FTIR) spectrometry, the effective diffusion coefficient, De, of nitrate in a contaminated anthropogenic sediment was estimated as 7.34 x 10(-6)cm2 s(-1). This method, which requires as little as 1 mL of sediment sample, was able to measure the De of a chemical species with a reproducibility of +/-3% in about 5h. Based on this De and a pre-determined nitrate reduction rate, the profiles of nitrate concentration in two sediment columns were satisfactorily predicted from a mathematical model. Results showed that the profile in this aged sediment depended mainly on the diffusion of nitrate and, only to a much lesser degree, the rate of nitrate reduction. Measurements in 55 anthropogenic sediment samples collected from five locations and various depths of a contaminated site further showed that the De of nitrate increased linearly with the water content of the sediment, but decreased with the sediment density. The technique demonstrated in this study shall be applicable for the risk assessment of toxic pollutants in contaminated sediments, and for planning the spatial and time intervals of nitrate injection strategy in bioremediation.     

A new mathematical model to evaluate simazine removal in three different immobilized-biomass reactors

A new mathematical model based on the cinetical Langmuir equation is developed to interpret and predict the effectiveness of simazine (SZ) removal in immobilized-biomass reactor (IBR), to consider herbicide-support affinity (Cx), and herbicide-cell affinity (Cy). Three solid supports: sepiolite monolith, granular sepiolite, and alginate were used in pilot-scale reactors that were inoculated with Klebsiella planticola DSZ. The abiotic process was analysed by measuring the SZ sorption capacity of the reactor supports. Sepiolite monolith showed the maximum value for herbicide-support affinity (28.02+/-0.9%). The effectiveness of the biotic process was estimated considering the formation of biomass and SZ biodegradation. Granular sepiolite showed either higher affinity with SZ and viability rate (0.90) throughout the process, and SZ removal rate was 3.39+/-0.06 mg/h. The mathematical model presented in this paper provides useful insights into the interpretation of experimental data as well as prediction for the implementation of biological reactors.     

Homogeneous iron-catalyzed photochemical degradation of muconic acid in water

Iron photochemical oxidation has been used to remove muconic acid from water. Two different light systems were used: black lamps and solar irradiation. The effect of iron concentration, intensity of incident radiation, pH and presence of oxalic acid was investigated. The first two variables yield positive effects on the removal rate of muconic acid while higher efficiency was achieved at pH 3. Oxalic acid enhances the oxidation rate because of the formation of photoactive ferrioxalate ion. Stoichiometric results indicated formation of two hydroxyl radicals to degrade 1 mol of muconic acid. At similar experimental conditions, initial oxidation rates of muconic acid were higher when solar light was used to irradiate the aqueous solutions, although in this case, the oxidation process is stopped because of the consumption of photoactive species.     

Extreme wind speeds in mixed wind climates

In this paper, a technique is discussed which enables extreme wind speed probabilities in mixed wind climates to be determined. It is shown that in such wind climates the method is likely to yield more accurate probability estimates than the traditional Gumbel analysis of annual wind speed maxima, particularly for annual probabilities of less than 2% (i.e. return periods greater than 50 years). The technique requires a separate analysis of each significant wind-producing meteorological phenomenon and practical methods of achieving this are presented. Extreme wind speed parameters obtained from each analysis may then be combined to yield a “composite extreme wind speed diagram” and several examples illustrating this procedure are shown. By means of a numerical simulation of a typical mixed wind climate, a detailed study is made of the distribution of extreme wind gusts from different meteorological phenomena. This study indicates that a Gumbel analysis of 20 annual maxima may severely underestimate low annual probability (i.e. long return period) gust speeds.     

Effect of surfactants on the determination of aluminium in waters

Eleven surfactants representing pure cationic, anionic and nonionic detergents, four commercial detergents, sodium pyrophosphate, sodium tripolyphosphate, a soap and nitrilotriacetic acid (NTA) were investigated for their effect on the determination of aluminium in water using the eriochrome cyanine R, ferron-orthophenanthroline and chrome azurol S methods. Cationic, anionic and nonionic detergents at concentrations up to 2, 100 and 1000 mg l⁻¹, respectively, did not interfere. Sodium tripolyphosphate interfered badly above 1.0 mg l⁻¹, and therefore the interference by formulated detergents containing tripolyphosphate was serious. Concentrations of NTA, soap and sodium pyrophosphate had to be below 0.5, 10 and 20 mg l⁻¹, respectively, to limit the error to 5%.     

Radon and 'King Solomon's Miners': Faynan Orefield, Jordanian Desert

Concentrations of 222Rn were measured in ancient copper mines which exploited the Faynan Orefield in the South-Western Jordanian Desert. The concentrations of radon gas detected indicate that the ancient metal workers would have been exposed to a significant health risk and indicate that any future attempt to exploit the copper ores must deal with the hazard identified. Seasonal variations in radon concentrations are noted and these are linked to the ventilation of the mines. These modern data are used to explore the differential exposure to radon and the health of ancient mining communities.     

The use of desorbing agents in electrodialytic remediation of harbour sediment

Electrodialytic removal of Cu, Zn, Pb and Cd from contaminated harbour sediment was made with the emphasis of testing the effectiveness of different desorbing agents: HCl, NaCl, citric acid, lactic acid, ammonium citrate and distilled water. Extraction experiments with the desorbing agents were made prior to the electrodialytic experiments. The extractions showed that HCl was most efficient for metal desorption, probably due to the low pH and complexation with chloride. The metals were not extracted by distilled water. However, in the electrodialytic experiments, the removal was high when using distilled water and the desorbing agents did generally not enhance the heavy metal removal compared to distilled water. The only exception was with lactic acid, where the Cu removal was 20% higher compared to the other desorbing agents. The removal was 48% Cu, 80% Zn, 96% Pb and 98% Cd, when using distilled water. Metal speciation with the different desorbing agents was simulated with the geochemical model Visual MINTEQ version 2.15. Variations in the Cl concentration were found to be of crucial importance since it influences the formation of metal chlorocomplexes, especially uncharged species. All the acidic desorbing agents were predicted to form mostly cationic species, which was in agreement with the removal direction in the electrodialytic remediation experiments.     

Landslides inventory

Summary After a 10 year interval from the first state-wide registration of landslides, a new system of landslide register is being introduced in Czechoslovakia in relation to the transfer to the Geological Data Bank system for processing by electronic computer. Each recorded phenomenon is plotted on a map and described. The final record is made by means of a code on a punched register card ready for computerizing. In the field, however, a questionnaire form has to be filled up, arranged in such a way as to enable easy processing. From the field questionnaire, the data are transcribed on to a punched card by means of a numerical or alphabetical code. A review of the data to be recorded is given.

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Inventaire Des Glissements de Terrain

Résumé Dix ans après le premier enregistrement national des glissements de terrain, un nouveau système d’enregistrement est en cours d’installation en Tchécoslovaquie, ce qui permettra d’établir la liaison avec le système de la Banque de données géologiques et d’exploiter ces informations avec un ordinateur. Chaque phénomène enregistré est reporté sur une carte et décrit. L’enregistrement final est fait au moyen d’un code sur une carte perforée prête à être utilisée dans l’ordinateur; mais sur le terrain, on devra remplir une formule de questionnaire, préparée pour permettre un traitement aussi facile que possible. Les données du questionnaire de terrain doivent être transcrites sur une carte perforée au moyen d’un code numérique ou alphabétique. On donne la liste des informations à enregistrer.