Mercury (Hg) is a global pollutant that poses a serious threat to human and the environment. Rice was found as an important source for human exposure to Hg in some areas. In this study, the transportation and transformation of IHg and MeHg in rice plants exposed to IHg or MeHg were investigated. The IHg and MeHg concentrations in rice roots and shoots collected every five days were analyzed by HPLC-ICP-MS and SR-XANES. When exposed to MeHg, the percent of IHg in rice roots and shoots increased while MeHg decreased significantly, suggesting prominent demethylation of MeHg occurred. However no notable MeHg was found in both roots and shoots of rice plant when exposed to IHg. SR-XANES analysis further confirmed the demethylation of MeHg with rice. This study provides a new finding that demethylation of MeHg could occur in growing rice, which may be a self-defense process of rice plant.

In the present study, replicated paddy microcosm systems were used to investigate the environmental fate and trophic transfer of titanium nanoparticles (NPs) over a period of 14 days. Most TiO2 NPs immediately settled down in the sediment, and high accumulations of nano TiO2 in the sandy loam sediment and biofilm were observed. The test organisms (quillworts, water dropworts, duckweeds, biofilms, river snails, and Chinese muddy loaches) and environmental media (freshwater, sandy loam sediment) were exposed to sequential low doses (2 mg/L at 1 h, 4 days, and 9 days) or a single high-dose (6 mg/L) of TiO2 NPs. The bioconcentration factors (BCFs) of nano-TiO2 in biofilms, quillworts, duckweeds, and Chinese muddy loaches were higher in the sequential multi-dose group than in the single-dose group. Chinese muddy loaches showed higher bioaccumulation factors (BAFs) over their prey than river snails. The difference in the carbon isotope ratios between Chinese muddy loaches and river snails was less than 2‰, and an approximately 4‰ difference in the stable nitrogen isotope ratio was observed in the two aquatic predators from their major prey (e.g., biofilms or particulate organic matter). The trophic levels between biofilms and river snails and between biofilms and Chinese muddy loaches were 2.8 and 2.4 levels, respectively. These results indicate that these two predators consumed biofilm and other alternative preys at a higher level than biofilm. Although the trophic transfer rates of TiO2 are generally low, relatively higher biomagnification factors (BMFs) were found in Chinese muddy loaches (0.04–0.05) than in river snails (0.01–0.02). These results suggest that TiO2 NPs show greater movement in the sediment than in the water and that TiO2 NPs can be retained through aquatic food chains more after a sequential low-dose exposure than after a single high-dose exposure.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED | International audience | CWs for combined sewer overflow treatment (CSO CWs) are vertical flow filters with detention basin and fixedoutflow rate. They receive stochastic loadsinduced by urban runoff and protect natural waters against pollutants and streambed erosion.However, due to the stochastic nature of flows, concentrations and periodicity, optimizing CSO CW design requires a dynamic approach.Computational tools are available but process-based models are difficult to handle [1].Moreover, the absence of user interface in design-oriented tools (e.g. RSF_Sim [2]) demands manual data handling and simulations of multiple designs. Therefore, a new tool called Orage was developed. Orage relies on a core model similar to RSF_Sim.Long-term hydraulics, COD and NH4-N were simulated with good accuracy. Filter material selection and scaling is based on inflow data series and a low number of inputs. The iterative shell calls for simulations repeatedly to (1) optimize hydraulics; (2) select the simplest material which isnecessary to satisfy emission requirements on NH4-N and (3) determine the minimalfilter area at which legislative thresholds can be met. A design is optimized if the maximum of moving average on simulated effluent concentrations (Peak_MA_cc) is at the legislative threshold (NH4N) or below (COD). Fig. 1 shows an example of the iteration process.

International audience | Barrage fishponds may represent a significant surface water area in some French regions. Knowledge on their effect on water resources is therefore necessary for the development of appropriate water quality management plans at the regional scale. Although there is much information on the nutrient removal capacity of these water bodies, little attention has been paid to other agricultural contaminants such as pesticides. The present paper reports the results of a 1-year field monitoring of pesticide concentrations and water flows measured upstream and downstream from a fishpond in North East France to evaluate its capacity in reducing pesticide loads. Among the 42 active substances that had been applied on the fishpond's catchment, seven pesticides (five herbicides, two fungicides) were studied. The highest concentration in the inflow to the pond was 26.5 mu g/L (MCPA), while the highest concentration in pond outflow was 0.54 mu g/L (prosulfocarb). Removal rates of dissolved pesticides in the fishpond ranged from 0-8 % (prosulfocarb) to 100 % (clopyralid). Although not primarily designed for the treatment of diffuse sources of pesticides, the studied fishpond had the potential to do so.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED | International audience | Gas emissions of Vertical Flow Constructed Wetlands (VFCW) treating raw wastewater have been poorly investigated. One of the main issue measuring gas emissions on such systems is related to their high heterogeneity of flow conditions (surface water distribution, feeding/resting periods etc). It is thus of importance to develop a specific methodology to be able first to determine representative gas emission fluxes and then to decide how filter‘s operation can affect these emissions. This study investigates greenhouse gas emissions from a full-scale VFCW for raw wastewater treatment. The plant designed for 800 population equivalents combines two stages of vertical subsurface flow filters planted with Phragmites. Australis. Gaseous emissions were continuously monitored during three weeks representing an overall feeding/resting period (1/3 weeks). Several automatic closed chambers connected to an infrared analyzer were placed at different strategic positions of the filters and allowed the measurement of tens of gaseous fluxes per day and per position. Dissolved N2O concentration was measured in the inlet and the outlet of each filtration stage using N2O micro-sensors. A combination of on-line sensors for NH4+ and NO3- and 24-h composite samples was used to characterize the process performances of each filtration stage. Finally, O2concentration was regularly measured in the air phase of the porous media in order to evaluate the aerobic conditions of the filters. Ammonium removal was on average of 94% during the monitoring period. The continuous measurement highlighted strong spatial and temporal variability of gaseous fluxes. This latter was observed at different time scales (day, week, feeding/resting cycle) and was linked to: (i) the intermittent feeding of the filters, (ii) oxygen content in the porous media and (iii) environmental conditions such as the ambient temperature. Dissolved N2O flux represented about 20% of the total flux (gas + liquid) which indicates the importance of accounting the dissolved flux in the N2O budget. The two filtration stages exhausted contrasted fluxes of methane and nitrous oxide in relation to carbon load and oxygen availability for carbon removal and nitrification. From a methodological point of view, this study indicates that: (i) continuous monitoring of greenhouse gas fluxes during at least an overall filtration cycle and (ii) appropriate spatial sampling strategy are decisive for a reliable determination of emission factors in VFCWs. The overall N2O emission factor estimated during the monitoring period was of 0.78% of the influent total nitrogen which is 28 times higher than the default IPCC factor (0.023% of the TN load). As N2O emissions were strongly correlated to the oxygen concentration within the porous media, it is suspected that nitrification was the main contributor to N2O production in the VFCW studied.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED | International audience | This simulation study investigates the treatment performance of a French style single stage vertical flow constructed wetland using a zeolite layer in order to increase ammonia removal. For the modelling exercise, the CW"2D biokinetic model of the HYDRUS Wetland Module is used. The calibrated model is able to determine the effect of different depths of the zeolite layer on ammonia removal in order to optimize the design of the system. For calibration of the model, hydraulic effluent flow rates as well as influent and effluent concentrations of COD and NH4-N have been measured. To model the adsorption capacity of zeolite, Freundlich isotherms are used. The results present the simulated treatment performance within three different depths of the zeolite layer, 10 cm (default), 15 cm and 20 cm respectively. The increase of the zeolite layer depth leads to a decrease of the simulated NH4-N effluent concentration.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED | International audience | The classic design of French constructed wetlands (CW) consists in two successive stages of vertical flow filters (VFFs). While this configuration permits full nitrification, it also needs a large surface area (> 2 m²/pe). Therefore high ammonium removal efficiencies are of interest for compact systems such as single stage CW.The use of zeolite as filtrating medium could fix the problem thanks to itsexchange capacity and its high affinity for ammonium. Indeed, the ammonium is adsorbed during the feeding cycle then nitrified during the rest period.This study aims to assess the feasibility of ammonium removal by zeolite in a first stage VFF fed with raw sewage. Seven columns (40 cm-depth, 107 cm²) filled with zeolite under a gravel layer and one control without zeolitewere studied over four months. All columns, except a zeolite-control, were packed with inoculated media froma treatment plant. The columns have been operated in a sequential mode of feeding and rest periods of 3.5d and 7d, respectively, with synthetic solution of ammonium (100mgNH4-N/L). Two columns were fed with different concentrations of ammonium while two others were also fed sodium in order to assess the impact of the ammonium concentration and the presence of competitive species, respectively. The nitrogen concentrations (ammonium, nitrite and nitrate) were measured at the inlet and the outlet.

In recent years, a trend toward a declining proportion of male births has been noted in several, but not all, industrialized countries. The underlying reason for the drop in the sex ratio is unclear, but one theory states that widespread environmental endocrine disrupting chemicals affecting the male reproductive system in a negative manner could be part of the explanation. The present study was designed to investigate whether the urinary phthalate, pyrethroids and polycyclic aromatic hydrocarbons metabolites concentrations were associated with sperm Y:X ratio.The study population consisted of 194 men aged under 45 years of age who attended infertility clinic in Lodz, Poland for diagnostic purposes with normal semen concentration of 20–300 mln/ml or with slight oligozoospermia (semen concentration of 15–20 mln/ml) (WHO, 1999). The Y:X ratio was assessed by fluorescent in situ hybridization. Urinary concentrations of 1-hydroxypyrene were measured by high performance liquid chromatography, phthalate metabolites were analyzed using a procedure based on the LC-MS/MS methods and metabolites of synthetic pyrethroids were assessed by gas chromatography ion-tap mass spectrometry method.After adjustment for potential confounders (past diseases, age, abstinence, smoking, alcohol consumption, sperm concentration, motility, morphology) 5OH MEHP, CDCCA to TDCCA and 1-OHP was negatively related to Y:X sperm chromosome ratio (p = 0.033, p < 0.001, p = 0.047 respectively).As this is the first study to elucidate the association between the level of metabolites of widespread environmental endocrine disrupting chemicals (phthalates, synthetic pyrethroids, polycyclic aromatic hydrocarbons) on sex chromosome ratio in sperm therefore, these findings require further replication in other populations.

Bisphenol A (BPA), a monomer used in plastic manufacturing, is weakly estrogenic and a potential endocrine disruptor in mammals. Although it degrades quickly, it is pseudo-persistent in the environment because of continual inputs, with reported concentrations in aquatic environments between 0.0005 and 12 μg/L. BPA represents a potential concern for aquatic ecosystems, as shown by its reproductive and developmental effects in aquatic vertebrates.In invertebrates, endocrine-related effects of BPA were observed in different species and experimental conditions, with often conflicting results, indicating that the sensitivity to this compound can vary considerably among related taxa. In the marine mussel Mytilus galloprovincialis BPA was recently shown to affect early development at environmental concentrations. In this work, the possible effects of BPA on mussel embryos were investigated at the molecular level by evaluating transcription of 13 genes, selected on the basis of their biological functions in adult mussels. Gene expression was first evaluated in trocophorae and D-veligers (24 and 48 h post fertilization) grown in physiological conditions, in comparison with unfertilized eggs. Basal expressions showed a general up-regulation during development, with distinct transcript levels in trocophorae and D-veligers. Exposure of fertilized eggs to BPA (10 μg/L) induced a general upregulation at 24 h pf, followed by down regulation at 48 h pf. Mytilus Estrogen Receptors, serotonin receptor and genes involved in biomineralization (Carbonic Anydrase and Extrapallial Protein) were the most affected by BPA exposure. At 48 h pf, changes in gene expression were associated with irregularities in shell formation, as shown by scanning electron microscopy (SEM), indicating that the formation of the first shelled embryo, a key step in mussel development, represents a sensitive target for BPA. Similar results were obtained with the natural estrogen 17β-estradiol. The results demonstrate that BPA and E2 can affect Mytilus early development through dysregulation of gene transcription.