Embargo until 30 July 2019 | Activated carbon (AC) amendment has been shown to reduce bioavailability of hydrophobic contaminants in the bioactive layer of sediment. Unwanted secondary effects of AC amendment could be particularly undesirable for ecologically important seagrass meadows, but so far, only a few studies have been conducted on effects on submerged plants. The purpose of this study was to investigate effects on growth and cover of submerged macrophytes in situ after AC amendment. Test sites were established within a seagrass meadow in the severely contaminated Norwegian fjord Gunneklevfjorden. Here we show that AC amendment does not influence neither cover nor length of plants. Our study might indicate a positive effect on growth from AC in powdered form. Hence, our findings are in support of AC amendment as a low-impact sediment remediation technique within seagrass meadows. However, we recommend further studies in situ on the effects of AC on submerged vegetation and biota. Factors influencing seasonal and annual variation in plant species composition, growth and cover should be taken into consideration. | acceptedVersion

Embargo until 27 Oct 2019 | Acid deposition has led to acidification and loss of fish populations in thousands of lakes and streams in Norway. Since the peak in the late 1970s, acid deposition has been greatly reduced and acidified surface waters have shown chemical recovery. Biological recovery, in particular fish populations, however, has lagged behind. Long-term monitoring of water chemistry and fish populations in Lake Langtjern, south-eastern Norway, shows that around 2008, chemical recovery had progressed to the point at which natural reproduction of brown trout (Salmo trutta) reoccurred. The stocked brown trout reproduced in the period 2008–2014, probably for the first time since the 1960s, but reproduction and/or early life stage survival was very low. The results indicate that chemical thresholds for reproduction in this lake are approximately pH = 5.1, Ali = 26 μg l−1, ANC = 47 μeq l−1, and ANCoaa = 10 μeq l−1 as annual mean values. These thresholds agree largely with the few other cases of documented recovery of brown trout in sites in Norway, Sweden, and the UK. Occurrence and duration of acidic episodes have decreased considerably since the 1980s but still occur and probably limit reproduction success. | acceptedVersion

Oil biodegradation as a weathering process has been extensively investigated over the years, especially after the Deepwater Horizon blowout. In this study, we performed microcosm experiments at 5 °C with chemically dispersed oil in non-amended seawater. We link biodegradation processes with microbial community and metagenome dynamics and explain the succession based on substrate specialization. Reconstructed genomes and 16S rRNA gene analysis revealed that Bermanella and Zhongshania were the main contributors to initial n-alkane breakdown, while subsequent abundances of Colwellia and microorganisms closely related to Porticoccaceae were involved in secondary n‑alkane breakdown and beta‑oxidation. Cycloclasticus, Porticoccaceae and Spongiiabcteraceae were associated with degradation of mono- and poly-cyclic aromatics. Successional pattern of genes coding for hydrocarbon degrading enzymes at metagenome level, and reconstructed genomic content, revealed a high differentiation of bacteria involved in hydrocarbon biodegradation. A cooperation among oil degrading microorganisms is thus needed for the complete substrate transformation. | Microbial community and metagenome dynamics during biodegradation of dispersed oil reveals potential key-players in cold Norwegian seawater | acceptedVersion

It has been proposed that the multiple pressures of fishing and petroleum activities impact fish stocks in synergy, as fishing-induced demographic changes in a stock may lead to increased sensitivity to detrimental effects of acute oil spills. High fishing pressure may erode the demographic structure of fish stocks, lead to less diverse spawning strategies, and more concentrated distributions of offspring in space and time. Hence an oil spill may potentially hit a larger fraction of a year-class of offspring. Such a link between demographic structure and egg distribution was recently demonstrated for the Northeast Arctic stock of Atlantic cod for years 1959–1993. We here estimate that this variation translates into a two-fold variation in the maximal proportion of cod eggs potentially exposed to a large oil spill. With this information it is possible to quantitatively account for demographic structure in prospective studies of population effects of possible oil spills. | acceptedVersion

Some volcanic soils like andosols contain short-range order nanoclays (allophane) which build aggregates with a tortuous and fractal microstructure. The aim of the work was to study the influence of the microstructure and mesoporosity of the allophane aggregates on the pesticide chlordecone retention in soils. Our study shows that the allophane microstructure favors pollutants accumulation and sequestration in soils. We put forth the importance of the mesoporous microstructure of the allophane aggregates for pollutant trapping in andosols. We show that the soil contamination increases with the allophane content but also with the mesopore volume, the tortuosity, and the size of the fractal aggregate. Moreover, the pore structure of the allophane aggregates at nanoscale favors the pesticide retention. The fractal and tortuous aggregates of nanoparticles play the role of nanolabyrinths. It is suggested that chlordecone storage in allophanic soils could be the result of the low transport properties (permeability and diffusion) in the allophane aggregates. The poor accessibility to the pesticide trapped in the mesopore of allophane aggregates could explain the lower pollutant release in the environment. (Résumé d'auteur)

A combined approach merging stable isotopes and fatty acids was applied to study anthropogenic pollution in the Río Negro estuary. Fatty acid markers of vegetal detritus indicated considerable allochthonous inputs at freshwater sites. Correlative evidence of diatom fatty acids, δ13C, chlorophyll and particulate organic matter suggested the importance of diatoms for the autochthonous organic matter production at the river mouth. Low δ15N values (~0�) and high fatty acid 18:1(n-7) concentrations in the suspended particulate matter, in combination with the peaks of coliforms and ammonium, indicated a strong impact of untreated sewage discharge. The 15N depletion was related to oxygen-limited ammonification processes and incorporation of 15N depleted ammonium to microorganisms. This work demonstrates that the combined use of lipid and isotopic markers can greatly increase our understanding of biogeochemical factors and pollutants influencing estuaries, and our findings highlight the urgent need for water management actions to reduce eutrophication.

International audience | Both macroplastic and microplastic contamination levels were assessed for the first time in a tropical river estuary system, i.e. the Saigon River, that traverses a developing South East Asian megacity, i.e. Ho Chi Minh City, Vietnam. The analysis of floating debris collected daily on the Nhieu Loc - Thi Nghe canal by the municipal waste management service shows that the plastic mass percentage represents 11-43%, and the land-based plastic debris entering the river was estimated from 0.96 to 19.91 g inhabitant-1d-1, namely 350 to 7270 g inhabitant-1yr-1. Microplastics were assessed in the Saigon River and in four urban canals by sampling bulk water for anthropogenic fiber analysis and 300 μm mesh size plankton net exposition for fragment analysis. Fibers and fragments are highly concentrated in this system, respectively 172,000 to 519,000 items m-3and 10 to 223 items m-3. They were found in various colors and shapes with smallest size and surface classes being predominant. The macroplastics and fragments were mainly made of polyethylene and polypropylene while the anthropogenic fibers were mainly made of polyester. The relation between macroplastic and microplastic concentrations, waste management, population density and water treatment are further discussed.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED [ADD1_IRSTEA]Valoriser les effluents et déchets organiques | International audience | There are 20 full-scale Phosclean® filters for P removal being used together with treatment wetlands (TW) to treat wastewaters of small and medium-size communities, in France. Some of them are in operation for more than five years now, reason why some field experiences are being conducted under the project name of APPROVE (APatite for P Removal and Valorisation: an Evaluation) to assess the current performance and saturation conditions of full-scale filters. This paper will present fieldfeedback results from 4 different wastewater treatment plants (WWTP) with Phosclean® filters. WWTP A (filter A) has been monitored since its commission in 2017 to assess the effluent's pH evolution due to material dissolution in the very first stage of its life span. Three other WWTPs (B, C and D) with hydraulically different Phosclean® filters, in operation since 2012, are also monitored: vertical up-flow (filter B); vertical down-flow (filter C) and horizontal flow (filter D). Assessment of the treatment plants use regulatory surveys since the beginning of plants operations. As treatment plants have not the same capacity, the number of regulatory surveys is heterogeneous and not high enough to have a precise knowledge on saturation levels and retention kinetics. Consequently, additional measurement campaigns have been carried out over two years. Four-day campaigns have been carried out twice per year for each WWTP. In order to evaluate the P retention's performance, 24h-flow proportional samplings at the inlet and outlet of the Phosclean® filter were coupled to spotsamplings at different hydraulic retention times inside the filter to measure retention's kinetic. Online P-PO4 measurements at the outlet of the filter were also conducted to observe possible dynamic within a day. Mayor parameters as pH, conductivity, redox potential, TSS, BOD, COD, N, TP, P-PO4 3- as well as anions and cations were measured for these samples. For filter A, a flowmeter and an online pH probe at the outlet of the filter have been implemented for several months. To determine the nature of phosphate precipitates, SEM and DRX analyses were performed for solid samples taken at different points in the filters. Furthermore, fluorescein-tracer tests were carried out to precisely determine water retention times and possible short-circuiting, as well as dynamic penetrometer measurements to assess potential changes on the material density due to surface precipitation. Results of first campaigns show that P concentration at the outlet of filters C and D respect the maximal regulation limit for total phosphorous disposal after 5 years of operation. This is not the case for filter B, after 4 years of operation, which is over the regulation limit fixed at 2.5mgTP/L. Nevertheless, differences in the regulation limits, inlet P concentrations, hydraulic loads, operation and design, must be taken into consideration to analyze variations of filters performances. The evolution of TP concentrations along time will be presented for all filters according to saturation levels for comparison. Kinetics evolution as a function of saturation conditions will be also presented. Results show that filters B, C and D are at different saturation levels, being filter B the most saturated.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED [ADD1_IRSTEA]Valoriser les effluents et déchets organiques | International audience | This study aims to enlighten the geometric changes at the pore scale of filtering media of Vertical Flow Treatment Wetlands (VFTW) and their influence on oxygenation during the rest period. A 3-day ex-situ drying of six samples of a VFTW was carried out at controlled temperature, and relative humidity simulating the rest period. Samples (16-cm long) were taken at the end of the feeding period of a filter in the first stage and let dry. Three of the samples were sterilized before drying using gamma rays to differentiate oxygenation without bacterial activity. At 0, 1 and 3 days of drying, X-ray scans of the samples were performed to observe changes in the samples structure. After each scan, the oxygen transport within the sample was studied by measuring vertical oxygen concentration profiles. Although X-ray tomography allows small structure changes to be detected, it is necessary to modify the drying conditions perform a more realistic drying. The complexity of the results of oxygen profiles lead us to suggest the use of CFD tools to understand how oxygenation occurs.

Author's accepted version (postprint). | This is an Accepted Manuscript of an article published by Springer in Water, Air and Soil Pollution on 27/10/2018. | Available online: https://link.springer.com/article/10.1007/s11270-018-4013-9 | acceptedVersion