Current opinion: What is a nanoplastic?
With the large amount of attention being given to microplastics in the environment, several researchers have begun to consider the fragmentation of plastics down to lower scales (i.e., the sub-micrometer scale). The term “nanoplastics” is still under debate, and different studies have set the upper size limit at either 1000 nm or 100 nm. The aim of the present work is to propose a definition of nanoplastics, based on our recently published and unpublished research definition of nanoplastics. We define nanoplastics as particles unintentionally produced (i.e. from the degradation and the manufacturing of the plastic objects) and presenting a colloidal behavior, within the size range from 1 to 1000 nm.
(Environmental Pollution. vol. 235, n° 0269-7491, pp. 1030-1034, 01/04/2018)
GR, UR, INSU - CNRS, CNRS, Softmat, ICT, IRD, UT3, Comue de Toulouse, INC-CNRS, CNRS, Toulouse INP, Comue de Toulouse, UT3, Comue de Toulouse, INC-CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UPMC, CNRS, ISCR, UR, INSA Rennes, INSA, ENSCR, INC-CNRS, CNRS, IPREM, UPPA, INC-CNRS, CNRS
Comparison of living and dead benthic foraminifera on the Portuguese margin: Understanding the taphonomical processes
Dead benthic foraminifera (> 150 μm) were studied in 23 sediment cores from the Portuguese Margin at water depths between 20 and 2000 m and located on 4 transects off the Douro, Mondego, Tagus and Sado river mouths and 1 transect in the Estremadura. For 10 stations, the dead faunal vertical distribution (0–8 cm) was first investigated in 4 different sediment horizons per core to evaluate the sampling effort necessary to have a representation of the dead fauna deposited under different environmental areas. As a result, it appears that the faunal vertical distribution is constant, except for the deepest environments where fragile taxa were identified in the top layers only. Dead foraminiferal assemblages in the 4–5 cm layer for all stations were then compared to previously published living foraminiferal assemblages (of March 2011) from the same cores to evaluate the taphonomical processes affecting major species. This improves the knowledge of the faunal distribution for a better benthic foraminiferal proxy for paleostudies. There was a considerable loss of some species in the dead fauna. Firstly, this concerns the fragile organic-cemented agglutinated taxa such as Reophax spp., Glomospira charoides, or Bathysiphon spp. Secondly, some calcitic species such as Nonion scaphum, Cancris auriculus, Ammonia beccarii or Bulimina aculeata that were particularly abundant in the living fauna on the inner shelf under the late winter high river discharge conditions, were also far less dominant in the dead fauna. Lastly, other species like Cassidulina carinata, Valvulineria bradyana, and Bulimina marginata systematically showed higher abundance in the dead fauna at the mid shelf. These species, related to eutrophic conditions occurring in summer during the upwelling activity, were therefore not well represented in the living fauna, collected in March. Transport of allochthonous specimens may also account for higher contribution in the dead community of some species like Cibicides lobatulus, Asterigerinata mamilla or Haynesina depressula, especially in coastal environments where hydrodynamic processes (river flood, winter storm, coastal drift) are more vigorous. Several species (U. mediterranea, U. bifurcata, T. agglutinans, H. balthica or B. costata), however, show little or no difference in both abundance and spatial occurrence between the living and dead faunas and provide a stable signal for paleoclimatic investigations.
(Marine Micropaleontology. vol. 140, n° 0377-8398, pp. 1-16, 01/04/2018)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Usefulness of RTL-W1 and OLCAB-e3 fish cell lines and multiple endpoint measurements for toxicity evaluation of unknown or complex mixture of chemicals
Fish are currently used for the assessment of chemical toxicity. The REACh regulation and the European directive on the protection of animals used for scientific purposes both recommend the use of methods other than animal testing. In view of this, fish cell lines are increasingly used to provide fast and reliable toxic and ecotoxic data on new chemicals. The sensitivity of the Rainbow trout liver cell line RTL-W1 and Japanese medaka embryos cell line OLCAB-e3 were used with different toxicity endpoints, namely cytotoxicity, EROD activity, ROS production and DNA damage for various classes of pollutants displaying different modes of action but also with complex environmental mixtures. Toxicity tests were coupled with chemical analysis to quantify the chemical concentrations in cell cultures. Differences in sensitivity were found between fish cell lines. MTT reduction assay revealed that OLCAB-e3 cells were more sensitive than RTL-W1 cells. On the contrary, RTL-W1 gave higher response levels for the Fpg-modified comet assay and ROS assay. The OLCAB-e3 cell line did not express EROD activity unlike RTL-W1. This study highlights the capacity of the two different fish cell lines to measure the toxicity of individual toxicants but also environmental mixtures. Then, results obtained here illustrate the interest of using different cell lines and toxicity endpoints to assess the toxicity of complex or unknown mixture of chemicals.
(Ecotoxicology and Environmental Safety. vol. 150, n° 0147-6513, pp. 40-48, 01/04/2018)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Aragonite saturation state in a tropical coastal embayment dominated by phytoplankton blooms (Guanabara Bay – Brazil)
The dynamics of the aragonite saturation state (Ωarag) were investigated in the eutrophic coastal waters of Guanabara Bay (RJ-Brazil). Large phytoplankton blooms stimulated by a high nutrient enrichment promoted the production of organic matter with strong uptake of dissolved inorganic carbon (DIC) in surface waters, lowering the concentrations of dissolved carbon dioxide (CO2aq), and increasing the pH, Ωarag and carbonate ion (CO32 −), especially during summer. The increase of Ωarag related to biological activity was also evident comparing the negative relationship between the Ωarag and the apparent utilization of oxygen (AOU), with a very close behavior between the slopes of the linear regression and the Redfield ratio. The lowest values of Ωarag were found at low-buffered waters in regions that receive direct discharges from domestic effluents and polluted rivers, with episodic evidences of corrosive waters (Ωarag < 1). This study showed that the eutrophication controlled the variations of Ωarag in Guanabara Bay.
(Marine Pollution Bulletin. vol. 129, n° 0025-326X, pp. 729 - 739, 01/04/2018)
UFF, UFRGS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOCEAN, IPSL, ENS-PSL, PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, IP Paris, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS
Assessment of Lemna minor (duckweed) and Corbicula fluminea (freshwater clam) as potential indicators of contaminated aquatic ecosystems: responses to presence of psychoactive drug mixtures
The pharmaceutical products are emerging pollutants continuously released into the environment, because they cannot be effectively removed by the wastewater treatment plants. In recent years, questions have been raised concerning the environmental risks related to these pollutants. The goal of this research was to evaluate the responses in Lemna minor after 7 days and in Corbicula fluminea after differing durations (1, 3, 7, and 19 days) of exposure to the psychoactive drug mixture (valproic acid, citalopram, carbamazepine, cyamemazine, hydroxyzine, oxazepam, norfluoxetine, lorazepam, fluoxetine, and sertraline) in different concentrations (0, 0 + ethanol, drug concentration (DC) 1 = river water concentration, DC2 = effluent concentration, and DC3 = 10× effluent concentration). In this aim, growth parameters of L. minor, gluthathione S-transferase (GSTs), catalase (CAT), ethoxyresorufin-O-deethylase (EROD) and/or gene expressions (pi-gst, cat, cytochrome P450 4 (cyp4), multidrug resistant 1 (mdr1), and superoxide dismutase (sod)) were measured. GST activities increased significantly in L. minor exposed to DC3, but no changes were found in CAT activity. In C. fluminea, EROD activity was induced significantly in both gill and digestive gland tissues after 3 days’ exposure to DC3, while a GST increase was observed only in digestive gland tissues, suggesting that these pharmaceuticals induced an oxidative effect. Gene expression analysis revealed transient transcriptomic responses of cyp4, sod, and mdr1 under drug concentrations 2 or 3 and no change of expression for the other genes (cat and pi-gst) or condition (environmental drug concentration) tested. Finally, the data reported in this study represent important ecotoxicological information, confirming that this enzyme family (cyp4, sod, and mdr1) may be considered as a sensible and early indicator of exposure to drugs and emphasizing the involvement of selected genes in detoxification pathways.
(Environmental Science and Pollution Research. vol. 25, n° 0944-1344, pp. 11192-11204, 01/04/2018)
BTSB, INUC, Comue de Toulouse, ENA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LCE, CNRS, UFC, UBFC
Trophic transfer and effects of gold nanoparticles (AuNPs) in Gammarus fossarum from contaminated periphytic biofilm
This work addressed the trophic transfer and effects of functionalized gold nanoparticles (AuNPs) from periphytic biofilms to the crustacean Gammarus fossarum. Biofilms were exposed for 48 h to 10 nm positively charged functionalized AuNPs at two concentrations, 4.6 and 46 mg/L, and crustaceans G. fossarum grazed on these for 7 days, with daily biofilm renewal. Gold bioaccumulation in biofilm and crustacean were measured to estimate the trophic transfer ratio of these AuNP, and, for the first time, a transcriptomic approach and transmission electron microscopy observations in the crustacean were made. These two approaches showed cellular damage caused by oxidative stress and, in particular, an impact of these AuNPs on mitochondrial respiration. Modulation of digestive enzyme activity was also observed, suggesting modifications of digestive functions. The damage due to these nanoparticles could then have vital consequences for the organisms during chronic exposure.
(Environmental Science and Pollution Research. vol. 25, n° 0944-1344, pp. 11181-11191, 01/04/2018)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ICMCB, UB, INC-CNRS, CNRS, SEBIO, INERIS, URCA, ULH, NU, URCA, CNRS, URCA, IRSTEA
Sources and exchanges of mercury in the waters of the Northwestern Mediterranean margin
Ocean margins are focal regions in terms of mercury (Hg) exchanges between the continent and the open sea. The aim of this paper is to describe the distribution and partition of Hg between the gaseous, dissolved and particulate phases in the waters of the Northwestern Mediterranean (NWM) margin, in order to assess the Hg sources and exchanges within the continuum between the continental shelf (Gulf of Lions) and the open sea (Northern Gyre). Mean (± standard deviation) of total Hg species (HgT) concentrations in unfiltered water samples were 1.52 ± 1.00 pmol L-1 (n=36) in the inner shelf, 1.09 ± 0.15 pmol L-1 (n=30) along the slope, and 1.10 ± 0.13 pmol L-1 (n=99) in the Northern Gyre. The dissolved phase (<0.45µm) average concentrations were 0.80 ± 0.47 pmol L-1 (n=37) in the inner shelf, 0.93 ± 0.20 pmol L-1 (n=4) along the slope and 0.84 ± 0.10 (n=20) pmol L-1 in the Northern Gyre. The particulate fraction of Hg decreased very strongly seaward from around 60% on the shelf to 10-25% above the Northern Gyre. Very low dissolved HgT concentrations occurred in the inner shelf water, consistent with the results of incubation experiments, which demonstrated that shelf water is very efficient in both production and release of dissolved gaseous Hg into the atmosphere. In the North Gyre waters column HgT presents a distribution pattern inverse to that of dissolved oxygen, and a slight Hg enrichment in the deep layer (Western Mediterranean Deep Water). The Hg from the open sea water is the largest Hg input to the Gulf of Lions (∼5.7 kmol yr-1), whereas inputs from the riverine source account for ∼3.4 kmol yr-1 and atmospheric deposition for less than 0.5 kmol yr-1. The Hg accumulated in the sediments of the shelf is ∼4.5 kmol yr-1, including 0.6-1.7 kmol yr-1 in the Rhône prodelta sediments. The evasion to the atmosphere represents a Hg flux of ∼2.6 kmol yr-1.
(Progress in Oceanography. vol. 163, n° 0079-6611, pp. 172-183, 01/04/2018)
BE, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Ozonolysis of unsaturated BVOCs in the presence of SO2: formation of Stabilised Criegee Intermediates, their reactivity and role in the particle formation
Biogenic volatile organic compounds (BVOCs), including monoterpenes, are one of the most abundant chemical group in the troposphere having major influences on air quality, climate and human health through chemical oxidation processes and secondary organic aerosol (SOA) formation. It is now established that gas-phase ozonolysis of monoterpenes leads to the formation of Stabilized Criegee Intermediates (SCIs) which can act as atmospheric oxidant for trace gases and lead to the formation of sulfate aerosols. However, the fate of these biradical species remains uncertain and need further investigation. Here we present the results of the first set of experiments which are a part of the COGNAC project (Chemistry of Organic biradicals: GeNesis of AtmospheriC aerosols). We have investigated the gas-phase ozonolysis of several BVOCs, including isoprene, a-pinene and limonene, in the presence or absence of SO2, in order to explore the fate of different SCIs. Experiments were performed in HELIOS simulation chamber, a large 90m3 Teflon chamber (S/V = 1.2 m-1), using different analytical instruments for the chemical and physical characterization of the gaseous and particulate species: an in-situ FTIR for monitoring organic and inorganic infra-red absorbing species (optical length = 302.6 m) including SF6 for the calculation of the dilution rate, a PTR-ToF-MS 8000 (Ionicon Analytik Gmbh) for the gas-phase detection of the reacting monoterpenes and products, a Figaero-ToF-CIMS (Aerodyne Research) in H3O+ and acetate mode, allowing the detection of both gas and particulate phases, a chemical ionisation mass spectrometer (CIMS) for the detection of hydroxyl and peroxy radical species and sulfuric acid, and a ATD-GC-MS (Thermo Fisher Scientific). Measurements of ancillary data (particle size distribution and mass concentration, O3, CO, SO2 and HCHO concentrations) were also conducted using a set of online monitors. Kinetic rate constants of a-pinene, limonene and isoprene ozonolysis have been determined using an absolute method ((1.28±0.04) × 10^16, 2.02× 10^17, 2.25 × 10^-16 cm3.molecule-1.s-1, respectively). Since H2SO4 can be formed by the reaction between SCIs and SO2 (and by the reaction between SO2 and OH, if present), its concentration given by CIMS can therefore be used as a proxy for SCIs detection in this study. The Figaero-ToF-CIMS shows a significant response up to m/z 417 in the particulate phase. Analysis of the observed high-resolution mass spectra have been used for mass assignment. This set of experiments is a preliminary study for a better understanding of SCIs formation, reactivity and fate, and the reaction mechanism of monoterpene ozonolysis in the presence of SO2.
(01/04/2018)
ICARE, UO, CNRS, INSIS - CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IRCELYON, UCBL, INC-CNRS, CNRS, LPC2E, INSU - CNRS, UO, CNRS, CNES
Recent morphology and sedimentary processes along the western slope of Great Bahama Bank (Bahamas)
Carbonate slopes and associated resedimented deposits have recently gained renewed interest because they represent volumetrically significant parts of carbonate platforms. Carbonate slopes are highly variable compositionally, architecturally and spatially due to a spectrum of sediment sources, resedimentation processes and controlling factors. Here, new high resolution acoustic data (including EM302 multi-beam echo-sounder and very high resolution seismic) and piston cores document highly diverse and complex morphological features along the north-western slope of Great Bahama Bank. The recent morphology of the slope is the result of the interplay between depositional and erosive processes that vary through time and along strike. The different sedimentary processes are recorded as a Pleistocene lowstand surface, characterized by many erosional features and a Holocene sedimentary wedge along the upper to middle slope that partially covers the underlying Pleistocene surface. Sedimentary processes during the Holocene are dominated by density cascading flows, which export muddy aragonitic sediment from the platform top towards the slope. Sedimentation rates, however, vary along strike due to platform top morphology combined with the variable strength of the basinal current. Reefs and islands in the Bimini area block off-bank sediment export, and shoals and tidal deltas from Cat Cay to the south reduce the density cascading processes. Numerous small and large slope failure scars show the instability of the steep slopes of Great Bahama Bank. Bottom currents dominate the lower slope and the basin. Striations and moats are the morphological expressions of current directions, while areas of non-deposition document strong current and concomitant removal of off-bank transported sediment along parts of the slope, while the Santaren Drift and the drift on the north-western edge of Great Bahama Bank act as the depositional locus for the fine-grained sediments transported in the current.
(Sedimentology. vol. 65, n° 0037-0746, pp. 2088-2116, 31/03/2018)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Transient biogeochemistry in intertidal sediments: New insights from tidal pools in Zostera noltei meadows of Arcachon Bay (France)
Several studies highlighted the occurrence of circular pools in intertidal flats of different coastal systems and their transient water chemistry over both tidal and diurnal cycles. However, little is known about (1) the response of benthic biogeochemical reactions and fluxes at the sediment-water interface over such short time scales, and (2) the role of these tidal pools in the biogeochemical functioning of coastal systems. Based on in situ microprofiles and water sampling, we investigated the dynamics of dissolved oxygen (O2), nutrients, sulfides and metals, and the associated fluxes at the sediment-water interface in tidal pools from the Arcachon Bay (Atlantic coast of France). Our integrative approach included several tidal and diurnal cycles over two different seasons in the presence and absence of Zostera noltei. The results show that water temperature and light irradiance were the main factors driving the biogeochemical functioning of the tidal pools, as they controlled the physiological activity of the microphytobenthos. Changes in light radiations induced diurnal fluctuations of O2 concentrations within surficial sediment, thus resulting in fluctuations of the O2 diffusive fluxes at the sediment-water interface and of the O2 penetration depth in sediment. At high tide, the increase in turbulence above the sediment induced the advection of oxygenated water within the first millimeters of sediment, resulting in a significant increase in porewater O2 concentrations and sediment O2 penetration depth. Porewater sulfide concentrations and apparition depth were concomitant with the O2 dynamic over both diurnal and tidal cycles, indicating that intermediate redox diagenetic processes were impacted by O2 dynamic over such short time-scale. The rapid changes in redox processes in the sediment column are confirmed by a significant flux of dissolved manganese toward the water column during nighttime. The consumption of nitrate and the release of ammonium and phosphate, associated to the mineralization of the organic matter in the surface sediment did not appeared related however to such short time cycles. The efflux of dissolved silica from the sediment was most likely associated with the enhanced dissolution of Si-bearing particles in surface sediment at higher temperatures, although silica uptake by Z. noltei was also noted. This study clearly shows that tidal pools function as natural incubators of transient biogeochemical processes. A rough assessment of the nutrient budget at the scale of the bay indicates the tidal pools may contribute significantly to the biogeochemical functioning of Arcachon Bay.
(Marine Chemistry. vol. 200, n° 0304-4203, pp. 1-13, 20/03/2018)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CHROME, UNIMES