Horillo-Caraballo J. Marine Geology , 1, Jabbar M. Jaud M. Latteux B. Maron P. Paskoff R. Pinot J. Pirazzoli P.
La Houille Blanche , 1, Pouvreau N. Short A.
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- Géographie du littoral de Côte d'Ivoire!
Suanez S. Vanney J. This study aims to highlight morphological evolutions of a nearshore over the historical and multidecadal time scales. It is based on the establishment of a methodology for the interpretation of historical bathymetric data. The nearshore is an integrated part of the coastal zone, as well as beaches and coastal dunes.
The understanding of the dynamic of each of these components is essential required to understand the evolutions of the complete sedimentary system. Yet, nearshores remain poorly studied compared to the emerged part of the system, because of the limited access for scientific monitoring.
However, these processes are expected to be better understood to improve the coastal management and the marine sand extraction especially in a contemporary context of coastal sedimentary deficit e. The bathymetric data are the only source of available information about submarine morphology over the long term the last two centuries.
However, their utilization requires a strict methodology that avoids data misinterpretation. The method that is developed here to compare ancient and recent bathymetric data thus takes into account the differences in data accuracy, resolution, and coverage due to technologic evolutions between the beginning of the nineteenth century and nowadays. The nearshore is large and shallow with a slope of 0. This suggests that there is a significant sediment accumulation in this part of the nearshore despite an erosive context of the beach.
The bathymetric data set covers a long period, between and , for which we have four complete surveys on the study area. The first step in data processing consists in identifying the corrections required such as the contemporary sea level rise and the transformation in a common geodesic system.
The second step consists in estimating the vertical and horizontal errors for each survey by taking into account the specificity of each method of acquisition used. Based on these successive DEM it is possible to realize several operations such as cross-shore profiles and sand volume calculations.
La pénéplaine et les côtes bretonnes
Comparisons of DEM highlight sedimentary dynamic that results from erosion and accretion periods. Three tendencies appear: between and the nearshore had been considerably eroded; between and the situation reversed and the floor had globally raised; the recent period is submitted to erosion. Those results reveal that the nearshore morphology is affected by direct and indirect factors. Regarding the origins of such variability, several hypotheses can be formulated that imply natural factors such as the wave climate modification, extreme meteorological events and also anthropogenic factors such as the creation of the polder of Combrit at the middle of the nineteenth century and more recent sand extraction in the nearshore.
Plan Introduction. Variations historiques du niveau marin. Agrandir Original png, k. Agrandir Original png, 4,6M. Earthworm burrow systems have been recently characterized using 3D-microimaging, in particular using X-ray computed tomography CT 4,5 Figure 1. This technique allows a 3-dimensional reconstruction of earthworm movement in soil and its monitoring with time.
Therefore, the use of this technique will help us to determine any modification that may occur in the behavioural patterns of earthworms when they are introduced in an ecotoxic environment. The aim of the proposed internship will be to study the behaviour of different earthworm species in mesocosm configurations containing soil samples with different properties and contaminated in different configurations homogeneous contamination, contaminated in linear gradients 6 or soil with a discrete contamination spot.
In parallel, the burrow system of earthworms will be monitored with time using CT imaging, in order to discern earthworm behaviour in the contaminated scenarios considered. On the other hand, other basic toxicity features, such as reproducibility and survival will be assessed for each scenario, following OECD guidelines. These experiences will be a base for the discussion of the validity of standardized bioassays to be used in the field or in actual contaminated soil samples. In close collaboration with Dr. Julia Clause and Dr. A definite objective of the internship will be the writing of a publication in English on which the intern will be a co-author.
For further information or to apply contact maria. More information here. Comment varient-t-ils au cours du temps? Good knowledge in uni- and multivariate statistics with R program. English writing capacities. Student with a strong interest in data analysis. General context of the study: The assessment of the soil quality and its impact on ecosystem services and goods is a scientific and societal issue that has been widely debated in the literature over the last twenty years.
Several indicators of soil quality have been developed Obriot et al. This is an important shortcoming because estimators of soil quality based on a compartmentalization of physical, chemical and biological properties, without taking into consideration their interactions, are prone to underestimate the importance of synergies and trade-offs.
Abridged English version
To address this knowledge gap, Kibblewhite et al. Based on this framework, a CIRAD-IRD team developed a set of 9 indicators to assess three key soil functions: carbon transformation, nutrient cycling and soil structure evolution. This approach provides integrative information that can be closely linked to soil ecosystem services. The Biofunctool set has been applied in five experimental sites in Thailand in order to assess the impact of rubber tree plantation land use and induced land use change on soil functioning.
In each experimental site, a range of 4 to 6 treatments were studied with the Biofunctool set.
Géographie du littoral de Côte d'Ivoire
The study sites have also been described in terms of soil physical, chemical properties and soil biodiversity. This dataset allows us to test the impact of land use change on soil biodiversity and its consequences for ecosystem function in agricultural systems, which remains an opened question in an agricultural context. Objective: The objective of the internship is to acquire a mechanistic understanding of the impact of land use change on soil biodiversity and soil functioning using data from five rubber tree plantation experiments.
Methodology proposed: Assemble and curate the different datasets e. Aggregate the Biofunctool variables to create a soil functioning variable easily linkable to soil ecosystem services. Test alternative hypotheses on the relationship between soil biodiversity, physico-chemical properties and and functioning using mixed effects models and structural equation modeling 1 ex: Poeydebat et al. Expected output: Acquire a mechanistic understanding of therelationships between land use management, soil biodiversity and soil functioning in rubber tree plantations.
Prepare a master thesis report with the structure of a scientific paper. Bailly bailly agroparistech. Des connaissances en Agronomie seront un atout. Pour plus d'informations et pour les figure veuillez consulter le document ci-joint. Philippe Baveye; Dr. The study of the migration and behaviour of non-aqueous phase liquids NAPLs as fuels are in porous media is still in its infancy, and faces difficulties related to the non-uniform transport of this phase, principally due to the interaction of NAPLs with soil constituents i. NAPL migration may be hindered due to sorption and entrapment in pores, forming "pools" above less porous soil layers, slowing down its downwards migration, and becoming an almost permanent contamination source.
Therefore, the study of the soil processes that affect the migration pattern of a fuel plume is very much needed at this point, will have a significant impact on the research about fuel spill migration, and will provide a firm basis to develop forecast models.
The innovation of the proposed work relies on the use of X-ray computed tomography CT to obtain 3-dimensional images of the NAPL within soil pores Figure 1, see the attached document at the end of this offer and to monitor with time its movement under different soil-NAPL scenarios. The research project in which the internship will be integrated aims to study the influence of soil properties on the behaviour, dynamics and spatial distribution of NAPL spills.
The data obtained will be used in dynamic 3D-models to predict the migration and behaviour of NAPL spills in soil environments, taking into account the properties of the soil-fuel scenarios tested. The results of these experiments are expected to have a significant impact on the understanding of the migration of fuel spills, according to the properties of the soil. Contacts: philippe. ADP Devers-Lamrani et al. Nicolardot et C. Nicolardot Vermue, A. Philippot, N. Munier-Jolain, C.
Global Change Biology.
Connaissances en agronomie. Stefan Scheu Mentor: Dr. But one third of the world soils are already in a state of degradation, much of which is caused by declines in the soil physical structure, modifying the transport of water, nutrients and gases, and habitats for the soil biota. Soil aggregates are micro-to millimetre sized organo-mineral associations considered as the building bricks of the soil structure.
There is general understanding that soil aggregates are formed by the association of mineral primary particles, coupled together by organic debris or secretions, and rearranged by the movement of roots or soil organisms through the soil matrix. But precise mechanistic understanding of how the high diversity of the soil organisms interacting in complex food webs influences the formation and stabilization of aggregates is still lacking.
Abundant groups, such as collembolan, have been largely neglected despite their high potential influence respectively by crawling, moving micrometric soil particles and incorporating large amount of organic matter into their fecal pellets and molts.
La pénéplaine et les côtes bretonnes - Persée
As they feed in fungi, known for their important role in soil aggregation, an indirect role of Collembolan is as well expected through the modification of fungal growth and biomass, hyphae branching, or even fungal spore dispersion. Scientific aim: The aim of this internship is to investigate how collembolan influence soil aggregate formation and properties. The student will focus on the trophic interaction between collembolan and fungi and test how a set of collembolan species Heteromorus nitidus, Falsomia candida, Protaphorura armata, Mesaphorura sp.