[en] This study examined zinc availability in crude oil-polluted soils. The aim of the study was to determine the effect of zinc on the physiochemical properties of soils in relation to remediation activities. The study was located at a site in Nigeria where crude oil spillage had occurred over a period of 2 months. The region was characterized by quarternary, alluvium, meander belt, wooded back swamps as well as fresh water swamps and Sombreiro-Warri Deltaic plains with large deposits of petroleum and natural gas. Three different land units were studied, notably (1) unpolluted, (2) polluted without vegetation and (3) polluted with vegetation. Soil sampling was conducted using a transect method. Hydrometer analyses were conducted to determine particle size distribution, while a core method was used to determine bulk density. Soil pH, total carbon, phosphorus, and total nitrogen were also measured. An analysis of variance (ANOVA) was used to correlate and regress zinc availability against the selected soil properties. The study showed that zinc availability increased with increases in the value of the effective carbon cation exchange capacity in the unpolluted and polluted samples without vegetation. Zinc decreased with increased clay and organic matter content. Results suggested that soils must be reclaimed quickly in order to prevent additional degradation. 48 refs., 5 tabs., 4 figs.

[en] The objective of the present study is to determine the bioaccumulation of heavy metals in various organs of the fresh water fish exposed to heavy metal contaminated water system. The experimental fish was exposed to Cr. Ni, Cd and Pb at sublethal concentrations for periods of 32 days. The elements Cd, Pb, Ni and Cr were assayed using Shimadzu AA 6200 atomic absorption spectrophotometry and the results were given as μg/g dry wt. The accumulation of heavy metal gradually increases in liver during the heavy metal exposure period. All the results were statistically significant at p < 0.001. The order of heavy metal accumulation in the gills and liver was Cd > Pb > Ni > Cr and Pb > Cd > Ni > Cr. Similarly, in case of kidney and flesh tissues, the order was Pb > Cd > Cr > Ni and Pb > Cr > Cd > Ni. In all heavy metals, the bioaccumulation of lead and cadmium proportion was significantly increased in the tissues of Cyprinus carpio (Common carp)

[en] An investigation on varied types of termite mounds relative to the nearby soils that are not inhabited by the termites in different places of Cameroon show that the activity of the termites is increasing the contents of most major and some trace elements in the termite mounds, except for Si and sometimes Fe, Mn, Na and K. These released elements are relocated into newly formed mineral phases that are dissolved by either H₂O dilute HCl leaching. The Ca and Mn released by the termite activity testify for crystallization of Ca-Mg carbonates and phosphates as well as of Fe oxy-hydroxides and/or Mn hydroxides. Termite activity also induces an increase in the lanthanide contents, the mound materials being especially enriched in light lanthanides relative to the corresponding soils without termite activity. The shapes of the patterns support precipitation of Mn-Fe oxy-hydroxides and Ca carbonates-phosphates. The increased amounts of Eu and Ce linked to termite activity seem to relate to the occurrence of reducing agents that are released by the termites, modifying Eu⁺³ into Eu⁺² and Ce⁺⁴ into Ce⁺³, favoring in turn selective incorporation of Eu⁺² and Ce⁺³ in the new phases of the termite mounds. Another consequence of the termite activity is the precipitation of H₂O and HCl extractable phases having low Sr/Ca ratios. Even if the K/Rb values of the termite mounds are typical for common soil-forming silicate minerals, their relocation by an inorganic process alone does not explain an abnormally high ratio in the H₂O leachable mineral phases. It was also shown that the main source for K and Rb of the dissolved phases is not only the interlayer site of clay particles, but also nutrients immobilized in and by the termites

[en] Synergistic effect of atmospheric non-thermal plasma generated by dielectric barrier discharge and nano titania photo catalyst for benzene decomposition was tested. The paper indicated the effect of photo catalyst on removal efficiency of benzene, the compare of photo catalyst characteristic in different high temperatures by heat treatment, analysis of by-products. The results showed that the effect of degradation was visible by added photo catalyst in the plasma reactor. When concentration of benzene was 600 mg/m³ and electric field strength was 10 kV/cm, the removal efficiency of benzene was increased up to 81 % without photo catalyst. At the same condition, the removal efficiency was increased to 15 % higher with photo catalyst. Nano titania crystal was anatase crystal in 450 ^deg^C heat treatment which is best for benzene removal. The plasma reactor packed with photo catalyst shows a better selectivity of carbon dioxide than that without photo catalyst. By-products are mostly carbon dioxide, water and a small quantity of carbon monoxide

[en] The composite system can be prepared by incorporation of methylene blue into the channels of zeolite and by adsorption on the surface of the crystals. The composite photo sensitizer effectively absorbs the red light (kmax = 648 nm) and upon illumination with light-emitting diode at a fluence rate of 1.02 mW cm-2 generates effectively reactive singlet oxygen in aqueous solution, which was proved by EPR spectroscopy. To test efficiency for inactivation of pathogenic microorganisms, we measured photo killing of bacteria Escherichia coli and Staphylococcus aureus and yeasts Candida albicans. We found out that after the microorganisms have been adsorbed at the surface of such modified zeolite, the photo generated singlet oxygen quickly penetrates their cell walls, bringing about their effective photo inactivation. The growth inhibition reached almost 50 % at 200 and 400 mg modified zeolite in 1 ml of medium in E. coli and C. albicans, respectively. On the other hand, the growth inhibition of S. aureus reached 50 % at far smaller amount of photo catalyst (30 lg per 1 ml of medium). These results demonstrate differences in sensitivities of bacteria and yeast growth. The comparison revealed that concentration required for IC50 was in case of C. albicans several orders of magnitude lower for a zeolite-immobilized dye than it was for a freely dissolved dye. In S. aureus, this concentration was even lower by four orders of magnitude. Thus, our work suggested a new possibility to exploitation of zeolite and methylene blue in the protection of biologically contaminated environment, and in photodynamic therapy.

[en] Cadmium(II) is a toxic hazardous cation, whose presence in the environment causes great concern because of its bioaccumulation in organisms and bio amplification along food chain. Hence, the removal of cadmium compounds from industrial waters and wastewaters is particularly essential, which requires intensive experimental and modelling studies to deal with the problem. In this work, the ion exchange of Cd"2"+ ions from aqueous solution using microporous titanosilicates (ETS-4 and ETS-10) has been modelled using adapted Maxwell-Stefan equations for the ions transport inside the sorbent particles. The fundamentals of the Maxwell-Stefan equations along with correlations for the convective mass transfer coefficients have been used with advantage to reduce the number of model parameters. In the whole, the model was able to represent successfully the kinetic behaviour of 11 independent and very distinct curves of both studied systems (Cd2"+"/Na"+/ETS-4 and Cd"2"+/Na"+/ ETS-10). The predictive capability of the model has been also shown, since several uptake curves were accurately predicted with parameters fitted previously to different sets of experimental data.

[en] The phyto extraction of copper and zinc assisted by the chelators such as ethylene diamine tetraacetic acid, diethylene triamino pentaacetic acid, ethylene diamine di succinate and citric acid into sunflowers (H h can act as effective cation exchangers. The negatively charged chelator complexes prevented binding to the cell walls of the roots and allowed complexes to enter the cells. Organic content contains fewer soil nutrients and has fewer negatively charged functional groups, such as carboxical, phenolical and hydroxyl; these adsorb negative free metal cations and reduce metal mobility, leading to less plant uptake. Regardless of different soils’ varying organic content, plant propagation ability can be listed in descending order as follows: cattails > reeds > sunflowers > Chinese cabbage. The mechanism of metal uptake was apo plastic transportation. Metal accumulation levels in different parts of plants are listed in descending order as follows: roots > stems > leaves. This is similar to the findings of most studies.

[en] Application of microorganisms with ability of using environmental wastes such as lignocellulosic materials for converting them to high-value products is important from economical point of view. Valuable products such as single cell oil have a high potential to be used in various industrial fields including bio diesel production. Other important products are polyalcohols like xylitol, which are applicable in the food and pharmaceutical industries. In this study, Rhodotorula yeast was isolated from the leaves of Benjamin. Afterward, single cell oil production was evaluated in a nitrogen-limited medium, and the obtained oil was analyzed by gas chromatography– mass spectrometery. Moreover, xylitol was produced in a media containing xylose and analyzed by high-performance liquid chromatography technique. The yeast strain was identified using polymerase chain reaction method. single cell oil and xylitol production was also evaluated in a medium containing lignocellulosic materials and other forestry residues. This strain produced single cell oil and dry biomass of 9.7 and 16.14 g/L, respectively. In addition, in a medium with 140 g/L of xylose, xylitol production was found to be 49.28 g/L. Among waste materials, lipid content of 49 % on grass hydrolysate was found to be incredible. The obtained strain was identified as Rhodotorula mucilaginosa. The results of this study show that by the isolation of yeast with the potential of making use of waste materials, high-value products can be obtained. Therefore, it can be concluded that the mentioned bioprocess has not only environmental benefits but also is very important from economical view.

[en] Many regions around the globe, especially South Asia including Afghanistan and Pakistan and Central Asia, have extreme difficulties in accessing portable water and a stable energy supply. Some areas are covered with arid soil and salty water, while others have power transmission problems. Water evaporation from reservoirs is also another problem during high temperatures, thereby posing additional energy and water demands. This paper discusses the multiple prospects of floating photovoltaic technology in different regions of the world and highlights the importance of such technologies in already water-scarce regions like South Asia and Central Asia. This technology will prove to be highly feasible as it is an environment friendly and cost efficient and will help in reducing evaporation, achieving sustainable water supply and clean energy production and reducing greenhouse gas emissions. There is very minimal work done on floating solar technology; thus, there is immense need to explore and research on this technology on every level through information sharing.

[en] Fe/H₂O₂ and Co/PMS reactions were compared for L-proline degradation under different initial pH values, various transition metal salt and oxidant agent concentrations, as well with and without irradiation. The Fenton reaction took 60 min to degrade 90% of the L-proline, whereas the Fenton-like reaction achieved the same degradation after only 15 min. The best conditions for the Fenton-like reaction resulted from using 0.8 mM of cobalt salt with low PMS concentration (20 mM) at a neutral initial pH and without irradiation. Further experiments were performed using the Co/PMS system to estimate the effects of the other reaction conditions. The results of these experiments showed that pH, reagent concentration, and UV (λ = 365 nm) radiation had no significant effect on the degradation. Additionally, the Fenton-like reaction was made in heterogeneous phase, showing that the reaction proceed equally at same pH than homogeneous phase reaction with no significant effect of phase type used. Significant amount of cobalt was found being leached from the solid media to the water at acidic pH values during the heterogeneous process so the best process conditions were found at neutral pH where the amount of cobalt being leached was found negligible. The heterogeneous Fenton-like process was found feasible to be used for different contaminants degradation with no risk of increased toxicity related with cobalt leachate. The results of this work provide a good evaluation of heterogeneous and homogeneous Fenton-like reaction and suggest that high reagent concentrations are unnecessary for efficient contaminant removal in aqueous phase.