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Vasseur P.,CNRS Interdisciplinary Laboratory for Continental Environments | Bonnard M.,University of Reims Champagne Ardenne
Current Zoology | Year: 2014

Pollutant dynamics and bioavailability greatly differ in soil and aquatic systems. Therefore, specific approaches and models are needed to assess the impact of soil contamination to terrestrial ecosystems. Earthworms among other soil invertebrates have received more attention because of their ecological importance. They represent a dominant part of the soil biomass and are soil engineers regulating important soil processes, notably fertilization. The release in soils of pollutants known for their persistence and/or their toxicity is a concern. Exposure of terrestrial species to pollutants that may alter genomic function has become an increasing topic of research in the last decade. Indeed, genome disturbances due to genetic and epigenetic mechanisms may impair growth, as well as reproduction and population dynamics in the long term. Despite their importance in gene expression, epigenetic mechanisms are not yet understood in soil invertebrates. Until now, pollutant-induced changes in genome expression in natural biota are still being studied through structural alteration of DNA. The first biomarker relating to genotoxicant exposure in earthworms from multi-contaminated soils reported is DNA adducts measurements. It has been replaced by DNA breakage measured by the Comet assay, now more commonly used. Functional genomic changes are now being explored owing to molecular "omic" technologies. Approaches, objectives and results are overviewed herein. The focus is on studies dealing with genotoxicity and populational effects established from environmentally-relevant experiments and in situ studies. © 2014 Current Zoology. Source

Maul A.,CNRS Interdisciplinary Laboratory for Continental Environments
Risk Analysis | Year: 2014

Microbial risk assessment is dependent on several biological and environmental factors that affect both the exposure characteristics to the biological agents and the mechanisms of pathogenicity involved in the pathogen-host relationship. Many exposure assessment studies still focus on the location parameters of the probability distribution representing the concentration of the pathogens and/or toxin. However, the mean or median by themselves are insufficient to evaluate the adverse effects that are associated with a given level of exposure. Therefore, the effects on the risk of disease of a number of factors, including the shape parameters characterizing the distribution patterns of the pathogen in their environment, were investigated. The statistical models, which were developed to provide a better understanding of the factors influencing the risk, highlight the role of heterogeneity and its consequences on the commonly used risk assessment paradigm. Indeed, the heterogeneity characterizing the spatial and temporal distribution of the pathogen and/or the toxin contained in the water or food consumed is shown to be a major factor that may influence the magnitude of the risk dramatically. In general, the risk diminishes with higher levels of heterogeneity. This scheme is totally inverted in the presence of a threshold in the dose-response relationship, since heterogeneity will then have a tremendous impact, namely, by magnifying the risk when the mean concentration of pathogens is below the threshold. Moreover, the approach of this article may be useful for risk ranking analysis, regarding different exposure conditions, and may also lead to improved water and food quality guidelines. © 2014 Society for Risk Analysis. Source

Parat C.,University of Pau and Pays de lAdour | Pinheiro J.P.,CNRS Interdisciplinary Laboratory for Continental Environments
Analytica Chimica Acta | Year: 2015

This work presents the development of a new probe (ISIDORE probe) based on the hyphenation of a Donnan Membrane Technique device (DMT) to a screen-printed electrode through a flow-cell to determine the free zinc, cadmium and lead ion concentration in natural samples, such as a freshwater river. The probe displays many advantages namely: (i) the detection can be performed on-site, which avoids all problems inherent to sampling, transport and storage; (ii) the low volume of the acceptor solution implies shorter equilibration times; (ii) the electrochemical detection system allows monitoring the free ion concentration in the acceptor solution without sampling. © 2015 Elsevier B.V. Source

Duval J.F.L.,CNRS Interdisciplinary Laboratory for Continental Environments | Duval J.F.L.,University of Lorraine
Physical Chemistry Chemical Physics | Year: 2013

A theory is proposed for the dynamics of metal uptake by a spherical microorganism whose peripheral structure consists of a charged bioactive surface surrounded by a soft (ion-permeable) charged layer. The formalism explicitly considers the concomitant steady-state conductive diffusion transport of metals from bulk medium to the bioactive surface and the kinetics of intracellular metal internalisation described by a Michaelis-Menten mechanism. The spatial distribution of metals at the microorganism/solution interphase is derived from an explicit solution of the Nernst-Planck equation with differentiated metal diffusion coefficients inside and outside the microorganism soft surface layer. The metal concentration profile involves the interphasial electrostatic potential distribution governed by the Poisson-Boltzmann equation accounting for the dielectric permittivity gradient across the soft layer/solution interface. The resulting metal uptake flux is rationalized in terms of dimensionless metal-biosurface affinity and the ratio between limiting uptake flux and limiting conductive diffusion flux. Both parameters depend on background electrolyte concentration, microorganism soft surface composition and geometry via their connection to a Boltzmann surface term and a factor expressing the electrostatically-driven retardation or acceleration of metal diffusion. Illustrations demonstrate how metal transport dynamics impacts biouptake depending on electrolyte concentration and on the key bio-physico-chemical properties of the biointerphase. The mathematical framework is then applied to practical situations where a swarm of charged microorganisms deplete metals under steady-state transport conditions. Several depletion kinetic regimes are evaluated as a function of medium salinity and microorganism electrostatic features. Expressions of their characteristic timescales are derived and analogies with equivalent electrochemical circuits are formulated. © the Owner Societies 2013. Source

Mondy C.P.,Eawag - Swiss Federal Institute of Aquatic Science and Technology | Usseglio-Polatera P.,CNRS Interdisciplinary Laboratory for Continental Environments
Science of the Total Environment | Year: 2013

The full accomplishment of the European Water Framework Directive objectives has required from EU members three successive steps: (i) the evaluation of their water body ecological status, (ii) the risk assessment of different anthropogenic pressure categories and (iii) the implementation of appropriate management and restoration programs.We aimed at designing an innovative retrospective ecological risk assessment (ERA) tool working for most of the French wadeable rivers in a context of multiple anthropogenic pressures (step ii). This tool, including conditional tree forest (CTF) models, was built on combinations of benthic macroinvertebrate trait-based metrics for each of sixteen anthropogenic pressure categories.For eleven pressure categories, CTF models have given good impairment risk assessment (i.e. AUC. ≥. 0.70), even at moderate risk level and in a multi-pressure context. The four other models have provided poorer but promising results (AUC. =. 0.67. ±. 0.02).Identifying the potential weight of individual anthropogenic pressures that lead to biotic assemblage impairment in streams under multiple pressure scenario, is a key step for managers to implement appropriate stream restoration programs. Simultaneously considering the whole complexity of bio-ecological adaptations within biotic assemblages subjected to human pressures provides a functional diagnostic tool both (i) ecologically relevant and (ii) efficient for ERA. © 2013 Elsevier B.V. Source

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