ROULÉPUR: Evaluating innovative solutions for the source control of micropollutants associated with road and parking lot runoff
(28/06/2016)
LEESU, ENPC, UPEC UP12, TEAM, Cerema, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LCPP
Les monuments mégalithiques submergés de la côte léonarde
Les sociétés néolithiques et de l’âge du Bronze ancien installées en Bretagne ont érigé de nombreux monuments mégalithiques (tombes, pierres dressées) en bord de mer. Aujourd’hui plusieurs d’entre eux, ensevelis sous les dunes ou submergés par la mer, sont des témoins spectaculaires de l’évolution du littoral qui s’est opéré durant ces derniers millénaires. Cette étude s’intéresse à trois monuments mégalithiques submergés, situés sur la côte nord de l’ancien pays du Léon. Il s’agit de deux allées couvertes situées respectivement dans l’anse de Kernic (Plouescat) et dans l’anse de Tréssény (Kerlouan) ainsi que d’un ensemble mégalithique (un menhir et probablement une enceinte mégalithique) se trouvant dans l’anse de Saint-Cava à Plouguerneau. Afin d'apporter une lumière nouvelle sur ces sites, une approche pluridisciplinaire relevant à la fois de l’archéologie, de la géologie et de la géographie est mise en œuvre. L’étude a d’abord pour but d’établir une méthodologie spécifique d’étude, applicable au contexte difficile qu’est l’estran et en utilisant des nouvelles technologies de relevés en trois dimensions. En effet, ces monuments subissent une submersion biquotidienne par la mer et ne sont donc accessibles aux observations uniquement durant des brefs instants. Ensuite, un soin particulier est apporté à l’observation des blocs constituants les monuments. Ces derniers sont étudiés tant d’un point de vue de la technologie, apportant des informations sur les modes de mise en œuvre des blocs, que d’un point de vue de la pétrographie afin d’identifier les roches utilisées lors de leur construction. Enfin, nous essayons de reconstituer l’environnement dans lequel chacun de ces sites a été construit et occupé.
(10/06/2016)
LDO, INSU - CNRS, UBO EPE, CNRS, LETG - Brest, LETG, UNICAEN, NU, UA, EPHE, PSL, UBO EPE, UR2, CNRS, IGARUN, UN
A survey of the summer coccolithophore community in the western Barents Sea
The Barents Sea is particularly vulnerable to large-scale hydro-climatic changes associated with the polar amplification of climate change. Key oceanographical variables in this region are the seasonal development of sea-ice and the location and strength of physico-chemical gradients in the surface and subsurface water layers induced by the convergence of Arctic-and Atlantic-derived water masses. Remote sensing imagery have highlighted the increasing success of calcifying haptophytes (coccolithophores) in the summer phytoplankton production of the Barents Sea over the last 20 years, as a response to an overall larger contribution of Atlantic waters to surface and sub-surface waters, as well as to enhanced sea-ice melt-induced summer stratification of the photic layer. The present study provides a first thorough description of coccolithophore standing stocks and diversity over the shelf and slope of the western Barents Sea from two sets of surface and water column samples collected during August-September 2014 from northern Norway to southern Svalbard. The abundance and composition of coccolithophore cells and skeletal remains (coccoliths) are discussed in view of the physical-chemical-biological status of the surface waters and water column based on in-situ (temperature, salinity, fluorescence) and shore-based (microscope enumerations, chemotaxonomy) measurements, as well as satellite-derived data (Chl a and particulate inorganic carbon contents). The coccolithophore population is characterized by a low species diversity and the overwhelming dominance of Emiliania huxleyi. Coccolithophores are abundant both within the well stratified, Norwegian coastal water-influenced shallow mixed layer off northern Norway, as well as within well-mixed cool Atlantic water in close vicinity of the Polar Front. Bloom concentrations with standing stocks larger than 4 million cells/l are recorded in the latter area north of 75°N. Our limited set of chemotaxonomic data suggests that coccolithophores contribute substantially (ca. 20% of the total Chl a) to the summer phytoplankton community which is made essentially of small-sized algal groups. Excluding the bloom area, coccolith calcite accounts for an average of 20% to the bulk particulate inorganic carbon content in the surface waters, and explains to some extent the satellite-derived spatial distribution of this parameter. Deep water living coccolithophore species thriving below the pycnocline as well as populations present in well-mixed cool Atlantic water are rapidly transferred to depth in the form of intact coccospheres down to at least 200 m. High amplitude internal waves which, according to our observations, affect a wide range of water depth up to the lower photic zone, might strengthen the vertical transfer of this sinking population.
(Journal of Marine Systems. vol. 158, n° 0924-7963, pp. 93-105, 01/06/2016)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CAIRN, Inria, IRISA-D3, IRISA, UR, INSA Rennes, UBS, ENS Rennes, Inria, CNRS, BIAF, UA, SHOM
Selection of an appropriate aqueous nano-fullerene (nC60) preparation protocol for studying its environmental fate and behavior
The inevitable future environmental release of fullerene nanoparticles (nC60) requires the development of specific analytical methodologies that are able to identify, characterize and quantify these new nanomaterial species. As is well detailed in the literature, the characterization of nanoscale materials requires the consideration of several physical and chemical parameters, such as size, size distribution, shape, charge surface, and surface chemistry. All of these parameters must be determined to assess the representative impact of manufactured nanoparticles in environmental media. Nevertheless, appropriate and environmentally representative nanoparticles standards are not currently available for the development of such analytical strategy and validating measurements. This tentative critical review presents a different pathway for the preparation of fullerene nanoparticles in aqueous media for environmental studies (characterization, fate and behavior determination). The principal drawbacks and bias measurement are presented as well as the consequences of this new pathway for our understanding of environmental implications.
(Trends in Analytical Chemistry. vol. 80, n° 0165-9936, pp. 1-11, 01/06/2016)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Analysis of modern pollen rain in the Limpopo basin, South Africa: Palaeoenvironmental and archaeological implications
(01/06/2016)
EPHE, PSL, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, WITS
Is herbicide toxicity on marine microalgae influenced by the natural dissolved organic matter (DOM)?
As primary producers, microalgae can be directly affected by herbicides. These organisms can also be impacted by other environmental elements such as the dissolved organic matter (DOM), that may also interact with pesticides. Indeed, MOD can affect pollutant transport, fate, biodegradation, bioavailability, and toxicity on organisms. Therefore, the present study aimed to investigate whether natural DOM influence the toxicity of three herbicides (irgarol (I), diuron (D) and S-metolachlor (S)), single and in mixture, on two marine microalgae, Chaetoceros calcitrans (Cc) and Tetraselmis suecica (Ts). After 6-day exposures to each herbicide (I0.05 and I0.5 µg.L-1; D0.05 and D0.5 µg.L-1; S0.5 and S5 µg.L-1) and to mixtures (M1: I0.05+D0.05+S0.5 and M2: I0.5+D0.5+S5), the effects of herbicides were assessed on growth (doubling time TD), photosynthetic yield (Yeff), reactive oxygen species presence and intracellular relative lipid content. For each condition, two sets of triplicates were run: one with natural DOM added to the culture media, another without DOM. Without DOM, I0.5 and M2 significantly affected almost all parameters with similar trends in both species: an increase of TD by more than twice (+125% and +129% for Cc and Ts respectively, at I0.5), a decrease of Yeff (approximately 30%) and a decrease of the relative lipid content. The M2 impacts observed in Cc were similar to the effects induced by irgarol at 0.5 µg.L-1, however a higher toxicity was shown for Ts (+167% for TD), suggesting a possible synergistic effect of mixture. When DOM was added in the culture media, significant effects were also observed with I0.5 and M2 conditions for both species: while the effects of I0.5 in TD of Cc were decreased (+101%), they were strongly enhanced for Ts (+178%), as were the effects of M2 (+298%). The presence of DOM decreased the herbicide toxicity for Cc whereas toxic effects were increased for Ts. These results may partly be due to the complexation between DOM and herbicides, leading to a lower bioavailability of herbicides. However, the difference in toxicity between the two species remains to be explained. Analysis of herbicide concentrations, dissolved organic carbon concentration and DOM, which are still ongoing, will help to improve the understanding of interactions between microalgae, herbicides and DOM. Finally, this study demonstrates the importance to consider DOM as a major factor possibly involved in toxicity modulation in the environment.
(pp. 1, 22/05/2016)
UR EABX, IRSTEA, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Game-based tools to transmit freshwater ecology concepts
There is an increasing expectation on people to be aware and to get involved in the environmental issues that our world is facing. However, expert knowledge is often required to understand most of these issues. One of the challenges in science today lies in explaining complex issues in a simple and understandable way to an unspecialized audience. Games can turn out to be a good medium for scientific vulgarization. Indeed, the first form of learning we all experienced was by playing. Games are very popular, and from an educational point of view, they present many advantages. They are dynamic and interactive. Therefore, the player engagement increases, as well as its knowledge retention. In addition, the player is immersed into a new world and discovers a virtual environment where he needs to develop strategies and to identify crucial processes. Those characteristics can be wisely used to spread scientific topics, and gamification has already been proposed as a tool for an easier propagation of scientific thinking such as in pharmacology or geosciences. In this context, our project aims at developing game-based tools to transmit the basic concepts of freshwater ecology. We choose to focus on a classical board game and on a computer based game because they are complementary in the targeted audience (groups versus online gamers) and the possibilities offered, in particular regarding the interactions between players and the system dynamics. The general methodology is divided in five steps: (1) selection of species; (2) definition of the instructions (object, game board, rules); (3) incorporation of environmental stressors (biotic and abiotic), (4) design and construction of interfaces (board and computer model); (5) test with players. All steps are necessarily interdependent and are tackled in parallel during the development of the games. While the board game is inspired by past experiences of player, the computer game is based on a model of simulation of the ecosystem. In order to introduce notions of equilibrium and its perturbations that occur at a larger time scale than on the board game, we propose to implement an agent-based model (ABM) and to couple its dynamics with gaming actions. ABM have already been widely used in ecology. Therefore, we selected a trophic chain dynamic model (extended prey-predator model) that can capture fish behavioral rules and spatially heterogeneous environment. It is particularly suitable for the game implementation: fish behaviors are influenced by players whereas the ecosystem is disturbed by external events. Both games are based on the same general rules, even if slight modifications have to be expected according to the type of game. Table 1 gives an overview on how the game can be introduced to a specific audience: The virtual ecosystem is presented from a fish perspective. The object of the game is to reach a given number of adults and juveniles that will guarantee the stability of the population in the lake. For this purpose, each player has to find resources accordingly to his fish species. The resources are converted into “units” that can be used thereafter by the player for different purposes, such as reproduction, juvenile growth, to escape a predator or to attack a pray. The external perturbations are illustrated by “events” that are supposed to reflect abiotic (e.g. water temperature, light, water scarcity) and biotic (e.g. chemicals, parasites, fisherman) stressors. The current version of the game includes four players, each of them being a different species, namely the roach (Rutilus rutilus), the pumpkinseed (Lepomis gibbosus), the zander (Sander lucioperca), and the bleak (Alburnus alburnus). The rationale behind lies in maximizing interactions between players (predation and competition, see fig. 1) and to illustrate feeding and reproduction strategies from different perspectives (from a big solitary fish to a shoal fish, including a invasive fish species). The board is basically composed of boxes. Each of them represents a type of resource (e.g. crustacean, plants, insects), and some boxes are combined with an “event” to include the external perturbations in the game. The player has 2 token on the board (one male and one female) and is moving them by throwing dice. The ecological characteristics of each species are kept on a record paper by each player. It describes the species-specific rules (feeding preferences, time and resources needed to reproduce, how to escape/attack etc). A first prototype is currently being tested to determine and adjust the board game design, the ecological characteristics of each species and the characterization of events, in particular their impacts on players. The design of the board is under progress and will figure the edge of a lake. The aforementioned species and natural ressources are the basis of the system. Discrete dynamics consist in the following steps : (a) wandering of species in their preferred zone of the lake; (b) trophic interactions (fish-fish and fish-ressources) ; (c) renewing of fish (reproduction) and of ressources. The model parameters include reproduction rates, movement parameters, etc. Large-scale model exploration and calibration are currently running in order to find parameter ranges at which ecosystem is in equilibrium1. The equilibrium will constitute the default state of the system without user control. User interactions are then integrated after each turn, at given time intervals (one month, when one time step is 6h for example). It allows the system to evolve in-between. During this time frame, the players observe the consequences of its actions and the reaction of the ecosystem to external events. Further developments will consist in model refinement and user latitude adjustments thanks to player feedbacks. A prototype of each game is currently available for testing and refinements are expected while experiencing the games. In a short term, next versions of the games will be developed after player feedback and will include the aesthetic design of the games and refined processes parameters. Mid-term and long-term objectives are oriented towards an online version of the computer game as described before, and the use of crowdfunding platforms to offer and diffuse the board game. The very first objective of our games remains to be entertaining, keeping in mind that the ludic rather than pedagogical aspects are central in the success of such game-based media. If players forget that the game is about ecology, our precise objective is reached. It would mean that the underlying scientific concepts are clearly understood.
(22/05/2016)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GC (UMR_8504), UP1, UPD7, CNRS, LVMT, IFSTTAR, UPEM, ENPC
Mercury concentrations in suspended particulate matter, water and mud-sediment up and downstream from old and recent gold mining sites in French Guiana
Although the use of mercury (Hg) for gold mining has been officially banned in French Guiana since 2006, there are still reasons to be wary of its occurrence in river water and its impact on local populations. In fact, gold-mining generates intense soil erosion and high turbidity in the rivers downstream from mining sites. This contributes to Hg pollution and dissemination both via the remobilization of Hg naturally present in the soils and the release of metallic Hg from the gold recovery process. In the affected rivers, Hg transport and speciation is mainly controlled by the suspended particulate matter (SPM) rather than remaining dissolved. The aim of this study is to understand and quantify the fate of this SPM-associated Hg along the Boulanger River affected by old and new gold mining activities. Furthermore we provide recent data (2012) essential to evaluate the efficiency of legal gold mining companies in restoring and re-planting exploited zones to control erosion, river turbidity and SPM transport. Inorganic Hg(II), monomethylmercury (MMHg) and turbidity measurements were measured in water, SPM and mud-sediment collected along the Boulanger River, from the spring down to its confluence with the Orapu River. The intensity of gold-mining in this area has been up and down through the last century and presents contrasting conditions with old and recently exploited areas. Dissolved Hg (HgD) levels were low (1-2 ng.L-1) and consistent with previous data known for the Amazonian area. Dissolved MMHg concentrations represented up to 8% of HgD which is higher than previous results (around 2%). Some relationships occurred between Hg concentrations in mud-sediment and turbidity values which both decreased downstream from the mining sites, then stabilized at 4-5 km further down. Hg contents in the mud-sediment show the impact of old and new gold mining practices. These results show that even though Hg use was banned from French Guiana 6 years ago, present gold mining practices still release significant amounts of Hg into the rivers. Survey intensification in French Guiana river systems should provide a more complete data set, essential to change gold mining practices and to reduce SPM and Hg contamination of the aquatic environment.
(22/05/2016)
BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UB
Modelling effects of temperature and oxygen on the population dynamics of the European sturgeon using dynamic energy budget theory
European sturgeon (Acipenser sturio) is an anadromous fish that breeds in rivers and which was previously found on most coasts of Europe. The last population of this species, nowadays listed as critically endangered, is reproducing in the Garonne basin near Bordeaux, south-west of France. In order to avoid extinction, the applied strategy since 1985 has been to release young fish into natural environment. These young individuals resulted from the assisted reproduction of wild and/or captive mature individuals. Recently recorded data in the Garonne basin show that in some sectors, where juveniles are likely to growth, summer temperatures have reached very high levels and water column has been hypoxic. Therefore, the combined influence of these factors on the young developmental stages needs to be assessed. The main goal of our project is to provide key information for improving the management of young fish release, especially age at release and release sites that maximize the fish survival. In this purpose, we will first calibrate a standard DEB model, based on the large dataset provided by the long term ex-situ stock breeding in our research institute. This model will firstly be used to evaluate the effect of temperature and oxygen on the survival rate of the first developmental stages. Other aspects of the life cycle will also be investigated, such as the link between maturity and the migration dynamics of the species and the impact of environmental conditions on eggs quality. The last part of our project will consist in the implementation of the standard DEB model within a pre-existing Individual Based Model (IBM) of the sturgeon population dynamics in the Garonne basin. This methodology will allow us to identify which individual traits are determinant in order to maximize the reinforcement of the sturgeon population in this basin.
(pp. 1, 08/05/2016)
UR EABX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Monitoring the Topography of a Dynamic Tidal Inlet Using UAV Imagery
Unmanned Aerial Vehicles (UAVs) are being increasingly used to monitor topographic changes in coastal areas. Compared to Light Detection And Ranging (LiDAR) data or Terrestrial Laser Scanning data, this solution is low-cost and easy to use, while allowing the production of a Digital Surface Model (DSM) with a similar accuracy. Three campaigns were carried out within a three-month period at a lagoon-inlet system (Bonne-Anse Bay, La Palmyre, France), with a flying wing (eBee) combined with a digital camera. Ground Control Points (GCPs), surveyed by the Global Navigation Satellite System (GNSS) and post-processed by differential correction, allowed georeferencing DSMs. Using a photogrammetry process (Structure From Motion algorithm), DSMs and orthomosaics were produced. The DSM accuracy was assessed against the ellipsoidal height of a GNSS profile and Independent Control Points (ICPs) and the root mean square discrepancies were about 10 and 17 cm, respectively. Compared to traditional topographic surveys, this solution allows the accurate representation of bedforms with a wavelength of the order of 1 m and a height of 0.1 m. Finally, changes identified between both main campaigns revealed erosion/accretion areas and the progradation of a sandspit. These results open new perspectives to validate detailed morphological predictions or to parameterize bottom friction in coastal numerical models.
(Remote Sensing. vol. 8, n° 2072-4292, 06/05/2016)
LIENSs, INSU - CNRS, ULR, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS