National audience | présentation invitée au colloque annuel de l'ARET Synthèse des travaux du Leesu sur les microplastiques en milieu urbain

Special Issue « ECOTOX, the INRA's network of ecotoxicologists »

The Mediterranean area is highly vulnerable to climate changes that combined with potential land use changes could influence its aquatic systems significantly. The Evros River is one of the most important surface water bodies in the Balkans with an ecologically significant delta that is protected by international legislation. The aim of this study is to analyze the impacts of climate and land use changes on Evros River water quality, for different climatic and socioeconomic scenarios. For this purpose, a hydrodynamic and advection-dispersion model was set up and calibrated, three IPCC climatic scenarios were applied, and the pollution loads of the catchment area were estimated. These scenarios involved river discharge decrease due to regional climate changes and socioeconomic and technological development that would lead to population growth and to the decrease of agricultural activities. The results indicated that in the case of discharge reduction only, the total nitrate and phosphate concentrations will be increased, while in case of combined land use and discharge changes, the concentration of nutrients will be decreased. Thus, a transboundary long-term management plan of the entire River is needed that would eliminate the pollution pressures and restore its good ecological status.

The economic downturn in Nigeria and Structural Adjustment Programme led to the flooding of Nigerian market with imported used automobiles. Most of these vehicles needed refurbishing and reworking. The present study is a human health risk assessment of metal exposure resulting from reworking of imported used vehicles in Nigeria. Scrap paint dusts from 56 Japanese made cars were collected from 8 different mechanic villages (workshops A–H] in Southeastern Nigeria. Scrap paints were homogenized, mixed, divided into fine particles and digested by standard method. The filtrates were assayed of lead, manganese and copper with atomic absorption spectrophotometry (AAS). Workshop B has the highest concentration of Pb (4.26 ± 0.93). Manganese in workshops A and F were (3.31 ± 0.85) and (3.04 ± 0.47) respectively and were higher than the levels from workshops C, B, D, G and H. Copper in workshop D (7.11 ± 0.21) was significantly greater than the other workshops. The highest hazard quotient (HQ) through ingestion, inhalation and dermal exposures in adults were 9.44E−05 (workshop B), 4.20E−01 (workshop B) and 1.08E−05 (workshop D) respectively. The highest values for HQ through ingestion, inhalation and dermal in children were 8.82E−04, 7.61E−01 and 2.86E−05 all in workshop B respectively. For children, the highest carcinogenic risk levels were 7.05E−08, 6.09E−05 and 2.29E−10 for ingestion, inhalation and dermal exposures respectively. In adults, the carcinogenic risk levels were 7.55E−09, 3.39E−05 and 8.67E−10 for ingestion, inhalation and dermal exposures respectively. Chronic exposure to scrap car paint dusts may be of significant public health importance in Nigeria as this may add to the body burden of some heavy metals.

The present work investigates the potential of two experimental field columns (FC-2 and FC-4) to reduce volatile organic compound (VOC) emissions from a municipal solid waste (MSW) landfill located in Quebec, Canada. The FC-2 and FC-4 were fed by raw biogas coming from the landfill site. The VOC were identified and quantified in emitted biogas and raw biogas. The emitted biogas was collected at the surface of FC-2 and FC-4, and the raw biogas was obtained directly from the well. The main groups of the VOC in the landfill biogas are BTEX (66 %), alkanes (19 %), cyclic compounds (10 %), and halogenated compounds (5 %). The concentration of VOC in the landfill raw biogas varies from below the limit of detection (BLD) to 22 ppmv, and that of the emitted biogas varies from BLD to 3.1 ppmv. The result of this study showed that the experimental field columns had a very high potential to reduce the VOC emissions from the investigated landfill. The effectiveness of the VOC emission removal for the FC-2 and FC-4 was shown to be practically 100 % for many compounds. The experimental field column elimination capacity of VOC emissions is in the range of 0.1 to 4.6 mg m⁻³ h⁻¹.

Sulfide, found in some wastewaters and industrial off-gases, is a toxic and highly corrosive pollutant, especially in wastewater applications. Sulfide removal was studied in a new sulfide-oxidizing reactor (External Silicone Membrane Reactor—ESMR) that employs a tubular silicone rubber membrane for micro-aeration. The chemical and biological sulfide oxidation at pH 8.0, 9.0, and 10.0 were investigated. The applied velocity (V ₛ) in the membrane was also investigated as a system control parameter. The local overall mass transfer coefficient (R) was estimated for the tubular silicone rubber membrane and had an average value of 0.153 m.h⁻¹. Oxygen mass transfer was found to not be influenced by the applied velocity. The sulfide oxidation to sulfate could be partially avoided and the biotic tests showed larger sulfur aggregates deposited in the silicone membrane, which could easily be washed away upon flushing. By contrast, colloidal sulfur formation observed in the chemical oxidation assays was harder to separate from the liquid phase. This study reveals that the ESMR is a suitable reactor design to promote partial sulfide oxidation because it provides an adequate oxygen supply with minimized aeration costs.

At present, the remediation of heavy-metal-polluted cropland soil is a considerable problem. In this study, in situ immobilization field experiment was conducted by planting rice (Oryza sativa L.) in low Cd-contaminated paddy soil to determine the optimal soil amendment that would reduce the accumulation of Cd in brown rice. GL (main component is alkaline residue), FG (main components are Si and Ca), and SH (main component is lime) were utilized as amendments. The remediation effects of the amendments on the soil and rice were investigated, and the potential mechanisms of reducing Cd availability to rice were analyzed. Amendment application significantly increased the soil pH value, reduced the DTPA-extractable Cd concentrations, and shifted Cd species from the exchangeable Cd fractions to the carbonate-bound, Fe-Mn oxides and residual fractions in paddy soil. For the plant, amendment application apparently increased the concentrations of Ca in rice plants, which could compete with Cd in root uptake. Besides, amendment application also effectively restricted the translocation of Cd from roots to shoots and consequently led to a notable decrease of Cd concentration in brown rice. These results demonstrated that the FG ameliorant could be effective in reducing Cd bioavailability and accumulation in rice grown on low Cd-contaminated paddy soils.

A macroporous glycidyl methacrylate (GMA)–methylmethacrylate (MMA)–divinyl benzene (DVB) terpolymer functionalized with diethylenetriamine tetraacetic acid (DTTA) (GMA-MMA-DVB-DTTA) sorbent was successfully applied for the uptake of Cu(II) from the aqueous solutions. Adsorption characteristics for copper ion were investigated by a batch sorption in under different experimental conditions, and the optimum parameters for the quantitative sorption of Cu(II) ion were found to be as follows: pH of 7.0, a contact time of 30.0 min, and a sorbent amount/solution volume ratio of 1.5 mg/mL. The quantitative elution from the sorbent was performed with 1.0 M HCl (>95 %). Among three kinetic models, the pseudo-second-order kinetic model provides the best correlation for the process. The nonlinear resolution of the Langmuir isotherm equation has been found to show the closest fit to the equilibrium data. The results indicates that the presence of the competitor ions (Al, Ba, Co, Mn, Mg, and Ni) has no obvious influence on the sorption of Cu(II) ion under the optimum conditions and the polymeric sorbent has a good selectivity for the sorption of Cu(II) ions with a sorption percent of ≥99 %. Sorption/desorption studies were performed for ultrapure, tap, bottled drinking and industrial wastewater samples, and it is examined that the proposed method has been successfully applied to the real samples for the removal of Cu(II) acceptable accuracy and precision. The results of this work indicated that the polymeric sorbent could be a simple and suitable method for the effective removal of Cu(II) ions from waters.

ANT is a commonly occurring polycyclic aromatic hydrocarbon (PAH) in natural eutrophic waters where Microcystis blooms break out usually. In this study, effects of ANT at different concentrations (0.02, 0.06, 0.18, 0.54, and 1.62 μg/mL) on the growth, microcystin-LR (MC-LR) production, and expression of three key mcy genes in Microcystis aeruginosa were investigated. The results showed that all the tested concentrations of ANT inhibited M. aeruginosa growth significantly except 0.02 μg/mL ANT in the early stage of the experiment. In the culture media, initially applied ANT concentrations decreased significantly after 3 days of incubation. ANT stimulated MC-LR production in a concentration-dependent manner. After exposure to ANT for 1 day, the expression of mcyB gene was inhibited and the inhibitory effects increased with ANT concentrations. ANT at higher concentrations (above 0.02 μg/mL) stimulated gene expression of mcyD (P < 0.05) and mcyH (P < 0.01) significantly, and 0.02 μg/mL of ANT inhibited their expression significantly (P < 0.01). With increasing culture time, 0.18 μg/mL of ANT inhibited mcyB gene expression first and then stimulated it while gene expressions of mcyD and mcyH were stimulated throughout the experiment. Our results suggested that ANT in natural waters could affect not only Microcystis growth but also MC production via modifying mcy gene expressions.