Methane biofiltration in the presence of ethanol vapor under steady and transient state conditions: an experimental study

Methane (CH₄) removal in the presence of ethanol vapors was performed by a stone-based bed and a hybrid packing biofilter in parallel. In the absence of ethanol, a methane removal efficiency of 55 ± 1% was obtained for both biofilters under similar CH₄ inlet load (IL) of 13 ± 0.5 g_CH4 m^?3 h^?1 and an empty bed residence time (EBRT) of 6 min. The results proved the key role of the bottom section in both biofilters for simultaneous removal of CH₄ and ethanol. Ethanol vapor was completely eliminated in the bottom sections for an ethanol IL variation between 1 and 11 g_ethanol m^?3 h^?1. Ethanol absorption and accumulation in the biofilm phase as well as ethanol conversion to CO₂ contributed to ethanol removal efficiency of 100%. In the presence of ethanol vapor, CO₂ productions in the bottom section increased almost fourfold in both biofilters. The ethanol concentration in the leachate of the biofilter exceeding 2200 g_ethanol m^?3 _leachate in both biofilters demonstrated the excess accumulation of ethanol in the biofilm phase. The biofilters responded quickly to an ethanol shock load followed by a starvation with 20% decrease of their performance. The return to normal operations in both biofilters after the transient conditions took less than 5 days. Unlike the hybrid packing biofilter, excess pressure drop (up to 1.9 cmH₂O m^?1) was an important concern for the stone bed biofilter. The biomass accumulation in the bottom section of the stone bed biofilter contributed to 80% of the total pressure drop. However, the 14-day starvation reduced the pressure drop to 0.25 cmH₂O m^?1.     

Chiral signature of venlafaxine as a marker of biological attenuation processes

The chiral signature of the antidepressant venlafaxine was used in this study to gain insight into biological attenuation processes and to differentiate abiotic and biotic transformation processes in water. Laboratory scale experiments revealed that sorption and phototransformation processes were not enantioselective while venlafaxine was enantioselectively biotransformed into O-desmethylvenlafaxine. The enantiomeric fraction (EF) variations of venlafaxine appeared to be proportional to its microbial fractional conversion. Enantioselective biotransformation of venlafaxine was also investigated in a eutrophic French river. Venlafaxine was found to be racemic at the output of the main wastewater treatment plant discharging into the river, independently of the sampling date during the year. An analysis of EF variations might provide evidence of biodegradation along a 30 km river stretch.     

Arsenic in marine sediments from French Mediterranean ports: Geochemical partitioning,bioavailability and ecotoxicology

This work investigates arsenic mobility, bioavailability and toxicity in marine port sediments using chemical sequential extraction and laboratory toxicity tests. Sediment samples were collected from two different Mediterranean ports, one highly polluted with arsenic and other inorganic and organic pollutants (Estaque port (EST)), and the other one, less polluted, with a low arsenic content (Saint Mandrier port (SM)). Arsenic distribution in the solid phase was studied using a sequential extraction procedure specifically developed for appraising arsenic mobility in sediments. Toxicity assessment was performed on sediment elutriates, solid phases and aqueous arsenic species as single substance using the embryo-toxicity test on oyster larvae (Crassostrea gigas) and the Microtox test with Vibrio fischeri. Toxicity results showed that all sediment samples presented acute and sub-chronic toxic effects on oyster larvae and bacteria, respectively. The Microtox solid phase test allow to discriminate As-contaminated samples from the less contaminated ones, suggesting that toxicity of whole sediment samples is related to arsenic content. Toxicity of dissolved arsenic species as single substance showed that Vibrio fischeri and oyster larvae are most sensitive to As(V) than As(III). The distribution coefficient (Kd) of arsenic in sediment samples was estimated using results obtained in chemical sequential extractions. The Kd value is greater in SM (450 L kg^?1) than in EST (55 L kg^?1), indicating that arsenic availability is higher for the most toxic sediment sample (Estaque port). This study demonstrates that arsenic speciation play an important role on arsenic mobility and its bioavailability in marine port sediments.     

Intestinal absorption of the acetamiprid neonicotinoid by Caco-2 cells: Transepithelial transport,cellular uptake and efflux

The human intestinal absorption of acetamiprid (AAP) using the Caco-2 cell line reveals that AAP flux was active in a bidirectional mode with an apparent permeability coefficient of 26^.10^?6 cm·s^?1 at 37°C. Apical uptake was concentration-dependent and unsaturated for AAP concentrations up to 200 μ M. AAP cell preloading demonstrated the involvement of active transport mechanisms. Arrhenius plot analysis revealed an unusual profile with two apparent activation energies suggesting two transport processes. Uptake Vi studies indicated the involvement of a sodium-dependent transporter, the presence of a common transporter of AAP and nicotine and the involvement of Ti-sensitive ATP-dependent efflux transporters. Apical efflux investigations showed the involvement of inward active transporter(s). Whereas vincristine had no effect on intracellular accumulation, taxol and daunorubicin treatments unexpectedly led to 10% and 23% reductions respectively, suggesting that the latter shared a common inward transporter with AAP. All these results suggest full and express AAP absorption in vivo with transport involving both inward and outward, passive and active mechanisms. Thus, AAP or its metabolites could be representative of a risk for human health after its ingestion in food.     

Evaluation of protective effects of sulforaphane on DNA damage caused by exposure to low levels of pesticide mixture using comet assay

The objective of the study was to evaluate the potential risk of DNA damage due to exposure to a mixture of the most widely used pesticides, namely endosulfan, chlorpyriphos and thiram at an environmentally relevant concentration (5 μM each) and the DNA protective capacity of sulforaphane (SFN) (10–30 μg/mL). DNA damage in human lymphocytes was ascertained with Single Cell Gel Electrophoresis (SCGE), also called Comet Assay. For positive control, H₂O₂ at 100 mM was used. The pesticide mixture produced DNA damage at the concentration used in the lymphocytes. SFN was able to offer a statistically significant (P < 0.01), concentration-dependant protection to DNA damage between 10–20 μg/mL in both the pre-incubation and co-incubation strategies. The results indicate that exposure to low levels of these pesticide mixtures can induce DNA damage, and the presence of SFN in diet may reduce the incidence of genetic damage, especially in farm workers. However, it is not clear whether SFN is involved in quenching of the free radicals generated by the pesticide mixture or it is involved in DNA repair mechanism.     

Deforestation and the Limited Contribution of Forests to Rural Livelihoods in West Africa: Evidence from Burkina Faso and Ghana

Forest degradation in West Africa is generally thought to have negative consequences on rural livelihoods but there is little overview of its effects in the region because the importance of forests to rural livelihoods has never been adequately quantified. Based on data from 1014 rural households across Burkina Faso and Ghana this paper attempts to fill this knowledge gap. We demonstrate that agricultural lands and the non-forest environment including parklands are considerably more valuable to poor as well as more well-off rural households than forests. Furthermore, product types supplied by the non-forest environment are almost identical with those from forests. Accordingly, forest clearance/degradation is profitable for and, hence, probably performed by rural people at large. We attribute rural people's high reliance on non-forest versus forest resources to the two countries' restrictive and inequitable forest policies which must be reformed to promote effective forest conservation, e.g., to mitigate climate change.     

Ex situ remediation of contaminated sediments using mineral additives: assessment of pollutant bioavailability with the Microtox solid phase test

The aim of this work is to assess the potential ecotoxicological effects of contaminated sediments treated with mineral additives. The Microtox solid phase test was used to evaluate the effect of mineral additives on the toxicity of sediment suspensions. Four Mediterranean port sediments were studied after dredging and bioremediation: Sample A from navy harbor, sample B from commercial port and samples C and D from pleasure ports. Sediment samples were stabilized with three mineral additives: hematite, zero-valent iron and zeolite. Results show that all studied mineral additives can act as stabilizer agent in highly contaminated sediments (A and C) by decreasing dissolved metal concentrations and sediment toxicity level. On the contrary, for the less contaminated samples (B and D) hematite and zeolite can provoke toxic effect towards Vibrio fischeri since additive particles can favor bacteria retention and decrease bioluminescence emission.     

Carbamazepine, carbamazepine epoxide and dihydroxycarbamazepine sorption to soil and occurrence in a wastewater reuse site in Tunisia

Although a number of manufactured nanoparticles are applied for the medical and clinical purposes, the understanding of interaction between nanomaterials and biological systems are still insufficient. Using nematode Caenorhabditis elegans model organism, we here investigated the in vivo toxicity or safety of hydroxylated fullerene nanoparticles known to detoxify anti-cancer drug-induced oxidative damages in mammals. The survival ratio of C. elegans rapidly decreased by the uptake of nanoparticles from their L4 larval stage with resulting in shortened lifespan (20 d). Both reproduction rate and body size of C. elegans were also reduced after exposure to 100 μg mL⁻¹ of fullerol. We found ectopic cell corpses caused by apoptotic cell death in the adult worms grown with fullerol nanoparticles. By the mutation of core pro-apoptotic regulator genes, ced-3 and ced-4, these nanoparticle-induced cell death were significantly suppressed, and the viability of animals consequently increased despite of nanoparticle uptake. The apoptosis-mediated toxicity of nanoparticles particularly led to the disorder of digestion system in the animals containing a large number of undigested foods in their intestine. These results demonstrated that the water-soluble fullerol nanoparticles widely used in medicinal applications have a potential for inducing apoptotic cell death in multicellular organisms despite of their antioxidative detoxifying property.     

Propiconazole inhibits the sterol 14α-demethylase in Glomus irregulare like in phytopathogenic fungi

The increasing concentrations impact (0.02, 0.2 and 2 mg L⁻¹) of a Sterol Biosynthesis Inhibitor (SBI) fungicide, propiconazole, was evaluated on development and sterol metabolism of two non-target organisms: mycorrhizal or non-mycorrhizal transformed chicory roots and the arbuscular mycorrhizal fungus (AMF) Glomus irregulare using monoxenic cultures. In this work, we provide the first evidence of a direct impact of propiconazole on the AMF by disturbing its sterol metabolism. A significant decrease in end-products sterols contents (24-methylcholesterol and in 24-ethylcholesterol) was observed concomitantly to a 24-methylenedihydrolanosterol accumulation indicating the inhibition of a key enzyme in sterol biosynthesis pathway, the sterol 14α-demethylase like in phytopathogenic fungi. A decrease in end-product sterol contents in propiconazole-treated roots was also observed suggesting a slowing down of the sterol metabolism in plant. Taken together, our findings suggest that the inhibition of the both AM symbiotic partners development by propiconazole results from their sterol metabolism alterations.     

Evaluating pharmaceuticals and caffeine as indicators of fecal contamination in drinking water sources of the Greater Montreal region

We surveyed four different river systems in the Greater Montreal region, upstream and downstream of entry points of contamination, from April 2007 to January 2009. The studied compounds belong to three different groups: PPCPs (caffeine, carbamazepine, naproxen, gemfibrozil, and trimethoprim), hormones (progesterone, estrone, and estradiol), and triazine herbicides and their metabolites (atrazine, deethylatrazine, deisopropylatrazine, simazine, and cyanazine). In the system A, B, and C having low flow rate and high TOC, we observed the highest detection frequencies and mass flows of PPCPs compared to the other compounds, reflecting discharge of urban contaminations through WWTPs and CSOs. However, in River D, having high flow rate and low TOC, comparable frequency of detection of triazine and their by-products and PPCPs, reflecting cumulative loads of these compounds from the Great Lakes as well as persistency against natural attenuation processes. Considering large differences in the removal efficiencies of caffeine and carbamazepine, a high ratio of caffeine/carbamazepine might be an indicative of a greater proportion of raw sewage versus treated wastewater in surface waters. In addition, caffeine appeared to be a promising indicator of recent urban fecal contaminations, as shown by the significant correlation with FC (R² = 0.45), while carbamazepine is a good indicator of cumulative persistence compounds.