Effects of combined sewer overflows on a periurban stream ecosystem: Methodological approach

International audienceHere we develop from a long term field experiment an assessment method of interstitial fauna resilience to combined sewer overflows (CSOs) effect. We address the case of small water courses for which the ratio of CSOs to natural flow can be 1 to much more. Biotic material was collected in the benthic and hyporheic layers. Biotic material focussed mainly on oligocheates species whose diversity, species category and abundance are resumed into metrics, called functional traits (FTrs), giving indications on flux dynamics and nutrient bio-assimilation capacity. The biotic resilience is assessed through the analysis of the response time of the biota to CSOs and natural flow characteristics, here called hydrological indices (HIs). In this aim, a series of hydrological indices are defined to reveal varying aspects of the dynamics of CSOs and natural flows. A main result is that CSOs can have both degrading and boosting effects on the biota of a stony stream. Some CSOs characteristics can explain the physical processes supporting these contrasting effects. In particular the geomorphic characteristics of the water course. Management perspectives emerge from the CSOs hydrological indices and resilience of the biota

From Research to Operational Biomonitoring of Freshwaters: A Suggested Conceptual Framework and Practical Solutions

International audienceThe contradictory demands of managers (quick relevant operational responses) and ecologists (need time for in-depth research) involved in freshwater biomonitoring are still relevant today. To contribute to solving this dilemma, we are proposing a novel biomonitoring approach, which among many others, could be used in this field and further developed in the future. Biomonitoring actions are integrated in conceptual schemes, in which hydrology, chemistry, hydrogeology and geomorphology bear as much importance as biology. Among biomonitoring tools, a harmonization system allows end-users to use a set of qualitative indicators (various biotic indices) and integrate the information given by individual biotic indices. Functional traits and calculation of an ecological potential in porous aquatic habitats (surficial coarse sediments and the hyporheic system) are regarded as a basis for assessing ecological functioning of streams and rivers. This last methodology takes into account the dynamics of water exchanges between surface water and groundwater. Objectives of ecological quality, ecological potentials and resilience capacity that need to be preserved or rehabilitated in aquatic habitats are established. In lakes, a similar approach was followed and a general typology of lake functioning was proposed, including that for urban lakes. All those biomonitoring tools are transferred to end-users and subject to further research. The final purpose is to promote practical high-tech tools which are continually and interactively connected with ongoing research

Les nouveaux patrimoines en situation urbaine. De la ville à la station balnéaire ou les logiques d’un processus qui intègre la valorisation touristique

Le mouvement de préservation du patrimoine, commencé au xixe siècle, a pris un essor considérable à la fi n du xxe siècle. Depuis quatre décennies, le champ patrimonial s’enrichit d’éléments du passé jusqu’ici ignorés ou peu considérés : patrimoines matériels naturels, paysager ou végétal ; patrimoine rural, artisanal, industriel, maritime, militaire et hospitalier. Et l’on observe désormais une percée très significative vers les patrimoines culturels immatériels. L’approche de tous ces nouveaux patrimoines est regroupée ici en plusieurs grands thèmes : l’eau, le relief, le rural et l’industrie comme patrimoines ; on y étudie aussi les nouvelles frontières du patrimoine, ainsi que les mutations méthodologiques introduites par la révolution du numérique. Richement illustré et doté de nombreuses cartes inédites, le présent ouvrage s’interroge sur la signification de cette montée des nouveaux patrimoines. Ce processus de patrimonialisation répond à une demande du public, il accompagne une volonté du citoyen, il contribue à la construction identitaire dans un contexte de mondialisation où chacun éprouve le besoin de racines culturelles. Est-ce un repli sur le passé ou bien une garantie pour la construction de notre avenir ? Sans vouloir trancher, on pourra constater que ces nouveaux patrimoines contribuent à promouvoir le respect de la diversité culturelle et la promotion de la créativité humaine. Cette montée des nouveaux patrimoines a aussi généré une réflexion sur l’économie du patrimoine. Qui doit financer ? Les associations, les régions ou l’État, les instances européennes et l’UNESCO ? Tous interviennent pour la valorisation du patrimoine car ils y voient un élément de développement durable des régions. Les Pays de la Loire, riches d’un patrimoine classique autant que de nouveaux patrimoines, se sont engagés dans cette voie d’une façon active et novatrice

Dielectric Properties of Materials Showing Constant-Phase-Element (CPE) Impedance Response

Constant-Phase Elements (CPE) are often used to fit impedance data arising from a broad range of experimental systems. Four approaches were used to interpret CPE parameters associated with the impedance response of human skin and two metal oxides in terms of characteristic frequencies and film thickness. The values obtained with each approach were compared against independent measurements. The power-law model developed recently by Hirschorn et al.1,2 provided the most reliable interpretation for systems with a normal distribution of properties. Readers are cautioned that the CPE parameter Q does not provide an accurate value for capacitance, even when the CPE exponent α is greater than 0.9