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UTILISATION INTEGREE DE BIOINDICATEURS POUR LA SURVEILLANCE DES SOLS ET DES ECOSYSTEMES TERRESTRES

Abstract : Transfer and effects of 3 metal trace elements (MTEs: Cd, Pb and Zn) in terrestrial food webs were studied over a 40 km2-area polluted by the former smelter Metaleurop Nord (France). The objectives were (i) to identify main factors explaining MTE concentrations in soils and studied animals, to determine scales of action of these variables and whether landscape modulate contaminations; (ii) to measure responses of considered species at various biological organization levels and to investigate relationships between responses of individuals and/or populations. Samplings of soils in woody habitats (suitable habitats for studied species), and several species of land snails and small mammals were performed during 3 consecutive years over two seasons. The spatial distribution analysis of soil contamination shows that variables explaining total soil concentrations (distance from the source, frequency of wind) act at relatively large spatial scales, while local factors (soil characteristics, notably pH) determine CaCl2-extracted soil concentrations (considered as available). Geostatistical methods of spatial interpolation, namely ordinary and universal kriging, allowed to produce soil contamination maps covering the whole study area and to establish a spatial risk assessment for invertebrates and vertebrates of woody habitats (based on US EPA Eco-SSLs). Relationships between MTE concentrations in animals and in soils were studied in sympatric snail species (Cepaea sp and Oxychilus draparnaudi) and small mammal species (the greater white-toothed shrew Crocidura russula and the bank vole Myodes glareolus) having contrasted diet. Internal concentrations increase with soil contamination and are always better explained by total rather than CaCl2-extracted soil MTE concentrations, except in Cepaea sp. Landscape influences accumulated MTE levels and their increase along soil pollution gradient. The spatial scale for which correlation between internal and soil MTE concentrations was at best differed between species and landscape types. Both physiological and ecological factors, such as diet and also habitat preference and habitat exploitation, modulate MTE bioaccumulation. The influence of receptor characteristics (sex, age, diet...) on accumulation and sequestration of MTEs was studied in several sympatric small mammals (wood mouse Apodemus sylvaticus, bank vole, common shrew Sorex araneus and pygmy shrew Sorex minutus). Age more than gender, and species more than trophic level, influence MTE and metallothionein (MT) levels and their relationships. Three patterns of relationships between MTE accumulation abilities and MTs production were identified. Individual health assessments suggest that receptor sensibility to MTEs (shrew < vole < wild mice) decrease when their MT production capability increase. Measure of MTs solely does not constitute a relevant exposure biomarker, however is necessary for interpretation of deleterious effect probability of occurrence. Temporal variability of MTE accumulation was studied in the bank vole, showing inter-annual and inter-seasonal differences. Whereas Pb (liver and kidneys) exhibit inter-seasonal variations (spring < autumn), both Cd and Zn have different patterns among organs, and inter-annual variations without straight seasonal effect. Potential adaptation to pollution in two autochthonous land snail species of study site, common garden snail Cantareus aspersus (formerly Helix aspersa) and grove (or brown-lipped) snail Cepaea nemoralis was investigated: offspring of parents from 2 origins (exposed to MTEs or not) were exposed in in situ microcosms within a cross-transplantation study. Analysis of MTE accumulation (biota-soil accumulation factor, kinetic modelling) does not show adaptation. However, shell characteristics suggest both acclimatization and adaptive processes through Ca metabolism modification. Present work show that analysis of organism responses to environmental pollution must be based on several parameters (bioaccumulation, biomarker, health index, population...), and that understanding the significance of a single measure necessitate to put it in perspective within its global context, moving across perception levels (biological organization level, temporal and spatial contexts). Within ecological risk assessment framework and pollution biomonitoring, our work emphasizes the need of long-term monitoring and the necessity to develop procedures over relevant spatial ranges in respect with ecological processes which participate in observed responses, and taking landscape into account.
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Submitted on : Friday, October 8, 2010 - 9:43:42 AM
Last modification on : Thursday, January 13, 2022 - 11:58:03 AM
Long-term archiving on: : Monday, January 10, 2011 - 11:10:13 AM

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  • HAL Id : tel-00524516, version 1

Citation

Clémentine Fritsch. UTILISATION INTEGREE DE BIOINDICATEURS POUR LA SURVEILLANCE DES SOLS ET DES ECOSYSTEMES TERRESTRES. Ecologie, Environnement. Université de Franche-Comté, 2010. Français. ⟨tel-00524516⟩

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