Application of chemical oxidation to remediate HCH-contaminated soil under batch and flow through conditions

This is the first study describing the chemical oxidation of hexachlorocyclohexanes (HCHs) in contaminated soil under water saturated and unsaturated flow through conditions. Soil contaminated with β-HCH (45 mg kg^?1) and γ-HCH (lindane, 25 mg kg^?1) was sampled from former lindane waste storage site. Efficiency of following treatments was tested at circumneutral pH: H₂O₂ alone, H₂O₂/Fe^II, Na₂S₂O₈ alone, Na₂S₂O₈/Fe^II, and KMnO₄. Experimental conditions (oxidant dose, liquid/solid ratio, and soil granulometry) were first optimized in batch experiments. Obtained results revealed that increasing dose of H₂O₂ improved the oxidation efficiency while in Na₂S₂O₈ system, maximum HCHs were removed at 300 mM. However, oxidation efficiency was slightly improved by Fe^II-activation. Increasing the solid/liquid ratio decreased HCH removal in soil samples crushed to 500 μm while an opposite trend was observed for 2-mm samples. Dynamic column experiments showed that oxidation efficiency followed the order KMnO₄ > Na₂S₂O₈/Fe^II > Na₂S₂O₈ whatever the flow condition, whereas the removal extent declined at higher flow rate (e.g., ~50% by KMnO₄ at 0.5 mL/min as compared to ~30% at 2 mL/min). Both HCH removal and oxidant decomposition extents were found higher in saturated columns than the unsaturated ones. While no significant change in relative abundance of soil mineral constituents was observed before and after chemical oxidation, more than 60% of extractable organic matter was lost after chemical oxidation, thereby underscoring the non-selective behavior of chemical oxidation in soil. Due to the complexity of soil system, chemical oxidation has rarely been reported under flow through conditions, and therefore our findings will have promising implications in developing remediation techniques under dynamic conditions closer to field applications.     

Effect of organic amendments on the mobility of trace elements in phytoremediated techno-soils: role of the humic substances

The efficiency of aided phytostabilization using organic amendments such as ramial chipped wood (RCW) and composted sewage sludge (CSS) was studied on contaminated techno-soils, on nine experimental plots. The objective was to characterize the role of fulvic (FA) and humic acids (HA) on the mobilization of trace elements, specifically As, Cu, Mo, Pb and Zn. Results showed that the addition of CSS increased the total organic carbon and nitrogen content more than with RCW and as a result, the C/N ratio in the CSS soil was higher than in the RCW and non-amended (NE) soil, reflecting the high decomposition of soil organic matter in the CSS soil compared with the other soils. The RCW and CSS amendments increased the hydrogen index (HI) values and the oxygen index (OI) values compared with the NE soil, especially for the soil treated with CSS which contained more aliphatic than aromatic compounds. The addition of CSS to the techno-soil significantly increased the percentage of C _org associated with the HA fractions compared with the RCW and NE soils. The soil amended with CSS showed the highest E ₄/E ₆ ratio and the lowest E ₂/E ₃ ratio of FA. Zn and As were more abundant in the FA fraction than in the HA fraction, whereas Pb, Cu and Mo were more associated to HA than to FA in the treated and untreated soils, which may explain the difference in their mobility and availability.     

Treatment of hydrocarbon contamination under flow through conditions by using magnetite catalyzed chemical oxidation

Soil pollution by hydrocarbons (aromatic and aliphatic hydrocarbons) is a major environmental issue. Various treatments have been used to remove them from contaminated soils. In our previous studies, the ability of magnetite has been successfully explored to catalyze chemical oxidation for hydrocarbon remediation in batch slurry system. In the present laboratory study, column experiments were performed to evaluate the efficiency of magnetite catalyzed Fenton-like (FL) and activated persulfate (AP) oxidation for hydrocarbon degradation. Flow-through column experiments are intended to provide a better representation of field conditions. Organic extracts isolated from three different soils (an oil-contaminated soil from petrochemical industrial site and two soils polluted by polycyclic aromatic hydrocarbon (PAH) originating from coking plant sites) were spiked on sand. After solvent evaporation, spiked sand was packed in column and was subjected to oxidation using magnetite as catalyst. Oxidant solution was injected at a flow rate of 0.1 mL min^?1 under water-saturated conditions. Organic analyses were performed by GC–mass spectrometry, GC–flame ionization detector, and micro-Fourier transform infrared spectroscopy. Significant abatement of both types of hydrocarbons (60–70 %) was achieved after chemical oxidation (FL and AP) of organic extracts. No significant by-products were formed during oxidation experiment, underscoring the complete degradation of hydrocarbons. No selective degradation was observed for FL with almost similar efficiency towards all hydrocarbons. However, AP showed less reactivity towards higher molecular weight PAHs and aromatic oxygenated compounds. Results of this study demonstrated that magnetite-catalyzed chemical oxidation can effectively degrade both aromatic and aliphatic hydrocarbons (enhanced available contaminants) under flow-through conditions.     

Analytical study of Asthart crude oil asphaltenes biodegradation

Various analyses of an asphaltenic fraction of Asthart crude oil enabled us to show that it was partially degraded by a marine mixed bacterial population with saturated hydrocarbons as cosubstrate. We also gave evidence of its strong biotransformation rate and tried to correlate its evolution with the nature of the produced fractions.     

Incidence of kyphosis deformities in natural population of <Emphasis Type="Italic">Atherina lagunae</Emphasis> (Trabelsi et al. 2002) from the Tunis North Lake,Tunisia

Vertebral abnormalities are common among fish and this constitutes a problem of quality and cost-efficiency in aquaculture and in fisheries. Information is presented on the occurrence of spinal deformities in natural population of Atherina lagunae (Teleostei, Atherinidae) in Tunis North Lake (Tunisia). This species is euryhaline and lives in most Mediterranean lagoons. A total of 2,175 fish were caught, in monthly samples, from October 2004 to August 2005. Deformed fishes were counted, photographed and radiographed. According to X-ray radiographies, kyphosis were the most common externally visible vertebral deformities. This abnormality was observed in 212 atherines (140 males and 72 females). The spinal deformity levels varied between 5.34% in December 2004 and 15.85% in June 2005, and averaged 9.75%. The rate of deformed fish varied considerably according to sex and size. The possible reasons of this deformity are also discussed.     

Effects of thermal desorption on the composition of two coking plant soils: impact on solvent extractable organic compounds and metal bioavailability

To evaluate the efficiency and the influence of thermal desorption on the soil organic compartment, contaminated soils from coking plant sites (NM and H) were compared to their counterparts treated with thermodesorption. The extractable organic matter, and the metal content and distribution with soil compartments were studied.In both thermodesorbed soils, PAH (polycyclic aromatic hydrocarbon) degradation exceeded 90%. However, the thermal desorption led not only to a volatilization of the organic compounds but also to the condensation of extractable organic matter.The treatments only affected the Fe and Zn distribution within the more stable fractions, whereas the organic compound degradation did not affect their mobility and availability.     

Consequences of prenatal diagnosis of cystic fibrosis on the reproductive attitudes of parents of affected children

Three hundred and twenty-six French families with a cystic fibrosis-affected child who were referred for prenatal diagnosis were analysed by sibship size: 74.2 per cent of the couples had no further pregnancies to term after the affected child, who was deceased in 34.6 per cent of cases. These couples were followed prospectively after prenatal diagnosis and 77 had two or more consecutive pregnancies with prenatal diagnosis. The aim of these couples was to succeed in constituting a family with two normal children.