[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED [Axe_IRSTEA]TED-EPURE | International audience | French vertical flow constructed wetlands treating raw wastewater have been developed successfully over the last 30 years. During the last years, SINT and Epur Nature developed the approach further by introducing a deep single-stage vertical flow bed that comprises both stages into one in the aim to reduce the footprint. This process, patented by Epur Nature as Bi-filtre®, consists in two vertical stages piled-up. While classical systems in France are designed with 2m².PE-1 (1.2m² and 0.8m² on the first and second stage respectively), the Bi-filtre® has a larger total filtration area with 2.5 m²/PE (1.5m² and 1 m² on the first upper and second lower stage respectively) but a foot print reduced to 1.5 m².PE-1. To favour aeration of the system, an intermediate natural aeration system is introduced at the interface between the first and second stage. The paper will present a study on a fullscale plant (Saint Michel l'Observatoire, 175 PE, France) running at full load in which different materials (sand, pozzolana of different particle size) were tested at the second stage. The aim was to identify the best materials to use to guarantee performance and avoid clogging on this unplanted and buried stage. The study consisted in measuring hydraulic conditions (inlet/outlet flows, infiltration rates, tracer experiments) correlated with 24h composite samples assessments. The results shows that such systems, if well designed, can guarantee an outlet quality of 35 mg.L-1 in SS, 125 mg.L-1 in COD, 25 mg.L-1 in BOD and 20 mg/L in KN with a total foot print of 1.5 m².PE-1. The paper will present the design recommendations and the limits of the systems taking into account a larger experience gathered on different existing plants (e.g. Chorges Bifilter®, 2 150 P.E, France).

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED [Axe_IRSTEA]TED-EPURE | International audience | Thus, choosing to plant local macrophytes species in CWs can be considered as an asset for the development of CWs, since it can be a part of global development projects which integrate cultural, social and economic characteristics. But, because of the ability of some macrophytes to accumulate toxic elements, human utilisation of CWs macrophytes has to be managed considering health damage potentiality. Spontaneous macrophytes diversity has to be appreciated for its key-role in the development of CWs in developing countries, not only from an ecological point of view, but also from cultural, social, sanitary and economic views.

The nature of soil organic matter (SOM) functional groups associated with sorption processes was determined by correlating partitioning coefficients with solid-state 13C nuclear magnetic resonance (NMR) and diffuse reflectance mid-infrared (DRIFT) spectral features using partial least squares (PLS) regression analysis. Partitioning sorption coefficients for n-pentadecane (n-C15) were determined for three alternative models: the Langmuir model, the dual distributed reactive domain model (DRDM) and the Freundlich model, where the latter was found to be the most appropriate. NMR-derived constitutional descriptors did not correlate with Freundlich model parameters. By contrast, PLS analysis revealed the most likely nature of the functional groups in SOM associated with n-C15 sorption coefficients (KF) to be aromatic, possibly porous soil char, rather than aliphatic organic components for the presently investigated soils. High PLS cross-validation correlation suggested that the model was robust for the purpose of characterising the functional group chemistry important for n-C15 sorption. NMR/IR spectroscopy and chemometrics reveal the aromatic fraction of soil organic matter being responsible for alkane sorption.

In an extensive environmental study, field samples, including soil, water, rice, vegetable, fish, human hair and urine, were collected at an abandoned tungsten mine in Shantou City, southern China. Results showed that arsenic (As) concentration in agricultural soils ranged from 3.5 to 935 mg kg−1 with the mean value of 129 mg kg−1. In addition, As concentration reached up to 325 μg L−1 in the groundwater, and the maximum As concentration in local food were 1.09, 2.38 and 0.60 mg kg−1 for brown rice, vegetable and fish samples, respectively, suggesting the local water resource and food have been severely contaminated with As. Health impact monitoring data revealed that As concentrations in hair and urine samples were up to 2.92 mg kg−1 and 164 μg L−1, respectively, indicating a potential health risk among the local residents. Effective measurements should be implemented to protect the local community from the As contamination in the environment. It is the first report on arsenic contamination and potential health risk implications at abandoned Lianhuashan tungsten mine.

Perfluorinated compounds (PFCs) were detected in sediment core samples collected in Tokyo Bay to reveal their time trends. The core sample deposited during 1950s–2004 was divided into two- to three-year intervals and the concentrations of 24 types of PFCs were determined. Perfluorooctane sulfonate (PFOS) decreased gradually from the early 1990s and its precursor decreased rapidly in the late 1990s, whereas perfluorooctanoic acid (PFOA) increased rapidly. The observed trends were regarded as a reflection of the shift from perfluorooctyl sulfonyl fluoride (PFOSF)-based products to telomer-based products after the phaseout of PFOSF-based products in 2001. The branched isomers of perfluoroundecanoic acid (PFUnDA) and perfluorotridecanoic acid (PFTrDA) were detected in the sample with its ratio of linear-isomer/branched-isomer concentrations decreasing. In this study, we revealed that the sediment core can serve as a tool for reconstructing the past pollution trend of PFCs and can provide interesting evidence concerning their environmental dynamics and time trend. This study reports the time trends of the concentrations of 24 species of PFCs, including FTCA, FTUCA and FOSAA, in a sediment core of Tokyo Bay, Japan. Keywords: Perfluorinated compounds

Numerous experiments have demonstrated reductions in the yields of cereal crops due to tropospheric O3, with losses of up to 25%. However, the only British econometric study on O3 impacts on winter wheat yields, found that a 10% increase in AOT40 would decrease yields by only 0.23%. An attempt is made here to reconcile these observations by developing AOT40 maps for Great Britain and matching levels with a large number of standardised trial plot wheat yields from many sites over a 13-year period. Panel estimates (repeated measures on the same plots with time) show a 0.54% decrease in yields and it is hypothesised that plant breeders may have inadvertently selected for O3 tolerance in wheat. Some support for this is provided by fumigations of cultivars of differing introduction dates. A case is made for the use of econometric as well as experimental studies in prediction of air pollution induced crop loss.

The metabolite 2,6-dichlorobenzamide (BAM) is a frequent groundwater pollutant produced during degradation of the herbicide 2,6-dichlorobenzonitrile (dichlobenile). Spatial variability of BAM mineralisation is uncharacterized in surface soil, however, and factors controlling the heterogeneity remain unknown. We addressed these issues by sample-to-sample comparisons of BAM mineralisation rates and a range of soil characteristics at spatial scales ranging from meters to centimetres. For mineralisation assays nano-molar concentrations of labelled BAM were added to determine mineralisation rates under realistic conditions. We found a significant variability of BAM mineralisation which increased with decreasing spatial scale. BAM mineralisation rates were correlated to the density of BAM-degrading bacteria but not to water content, TOC, NH4+, NO3−, or pH. The genus Aminobacter, which contains the only BAM degraders known, was detected in MPN samples of BAM degraders by a specific PCR assay targeting the 16S rRNA gene, confirming a role of Aminobacter in BAM mineralisation. Density of degrader bacteria is the main factor in BAM mineralisation when considering realistic low concentrations in soil.