Laboratory HydroSciences Montpellier

In the community working on karst hydrosystems, the needs for subsurface solute and contaminant transport characterization is widely acknowledge.  In former studies, several researchers addressed these needs with different approaches such as laboratory experiments, field tests, and groundwater flow and transport simulations. The main objective of such approaches is to improve knowledge of transport processes in karst hydrosystems, and propose solutions to limit the downstream hydrogeological risks (contamination of water resources). In this study, we performed a solute transport experiment in different karst aquifers, in the terminal karst conduit near the spring. We injected a dye in the karst conduit and we monitored the restitution of the tracer at three different zones downstream. In each zone, five probes were placed at different locations (middle, up, down, left and right parts of the cave) along the cross-section of the karst conduit.Experimental data allowed to reconstruct a transient spatial distribution of concentration for each zone and a general evolution of solute plume. It also provided information about dye mixing along the karst conduit. As a next step, these results are compared to simulated results to investigate the effect of karst conduit geometry, turbulent flow and velocity profiles on concentration profiles, mixing processes and the evolution of solute plume along the conduit. Preliminary results showed that the consideration of the complex karst conduit geometry and morphology has an important effect on transport processes, with a behavior notceably different from the one obtained with numerical simulations on simplified karst conduit geometries.

<p>To project the future of natural resources, the modeling of continental surfaces is identified as a key tool. In this study, an emphasis is given to the modeling of water and vegetal resources, whose interactions cannot be finely apprehended by current models. To this end, an agro-eco-hydrological model is proposed to quantify both the energy, water and carbon exchanges and the plant productivity of natural and agricultural ecosystems encountered in the agropastoral Sahel: millet cultivation and shrub fallow. This model is based on the physically-based SVAT model, SiSPAT (Braud et al., 2005). It mechanistically simulates vertical energy and water transfers in the continuum, and its high capability in the Sahelian zone has been fully demonstrated (Velluet et al., 2014). Processes specific to plant functioning and to carbon cycle were now added to the model: photosynthesis, stomatal regulation, seasonal plant phenology, and organ carbon allocation. This step was carried out for the millet crop using the formalisms described in the agronomic models SARRA-H from CIRAD (Dingkuhn et al., 2003) and STICS from INRAE (Brisson et al., 1998). Similarly, the description of natural ecosystems will soon be drawn from the ecological models STEP (Mougin et al., 1986) and TREEGRASS-2 (Boulain et al., 2014); all these models dedicated to vegetation having successfully been tested in the Sahelian context. The new version of the model has now the ability to simulate the seasonal development of agrosystems as a function of climate and energy and water availability. A first phase of exploitation of the integrated model has just been carried out in order to evaluate the robustness and relevance of the developments. It was conducted at the scale of a millet plot and with the support of multi-year observations acquired at the Wankama site (Cappelaere et al., 2009). The presentation will focus on the results as well as some perspectives of applications in future climatic changes.</p>

Scientists often set ambitious targets using environmental metabolomics to address challenging ecotoxicological issues. This promising approach has a high potential to elucidate the mechanisms of action (MeOAs) of contaminants (in hazard assessments) and to develop biomarkers (in environmental biomonitoring). However, metabolomics fingerprints often involve a complex mixture of molecular effects that are hard to link to a specific MeOA (if detected in the analytical conditions used). Given these promises and limitations, here we propose an updated review on the achievements of this approach. Metabolomics-based studies conducted on the effects of pharmaceutical active compounds in aquatic organisms provide a relevant means to review the achievements of this approach, as prior knowledge about the MeOA of these molecules could help overcome some shortcomings. This review highlighted that current metabolomics advances have enabled more accurate MeOA assessment, especially when combined with other omics approaches. The combination of metabolomics with other measured biological endpoints has also turned out to be an efficient way to link molecular effects to (sub)-individual adverse outcomes, thereby paving the way to the construction of adverse outcome pathways (AOPs). Here, we also discuss the importance of determining MeOA as a key strategy in the identification of MeOA-specific biomarkers for biomonitoring. We have put forward some recommendations to take full advantage of environmental metabolomics and thus help fulfil these promises.

Abstract BackgroundSeveral methods exist to collect and assess the abundance of dengue vector mosquitoes, i.e. morning adult collection using an aspirator, pupal collection, various ovitraps, whole night collection using human landing methods, and larval collection. This diversity of methods might be a source of variability and lack of statistical significance when trying to correlate mosquito density and risk of dengue outbreak. There is also a lack of published data regarding the effectiveness of these methods MethodsA mosquito survey was conducted in 39 locations corresponding to 15 dengue endemic provinces in Indonesia. The larval surveys were performed by collecting at least a single Aedes larva from each container, and then reared up until hatching. Three adult mosquito sampling methods were also used, including morning resting collection, human landing collection, animal baited trap. All field samples were tested for dengue. Factor Analysis of Mixed Data (FAMD) was conducted to analyze the effectiveness of the collection methods against mosquito species and dengue incidence.ResultsA total of 44,675 mosquitoes were collected. The single larva method was the most efficient method. Out of a total of 89 dengue-positive pools, the most frequently encountered virus was DENV2, which made up half of the positive samples, followed by DENV3 and DENV1, respectively. FAMD showed that no correlation could be found between any methods and the presence of dengue virus in mosquitoes. Moreover, no correlation could be found between either any methods or the incidence.ConclusionsThere was no concistency in the efficacy of a given method and the incidence of dengue in the human population. There was no correlation between any of the parameters considered, i.e. method, incidence of dengue, location and presence of dengue virus in mosquitoes. This indicates that entomological factors are not reliable indicators.

International audience