We consider an optimal consumption and pollution problem that has two important features. Environmental damages due to economic activities may be irreversible and the level at which the degradation becomes irreversible is unknown. Particular attention is paid to the situation where agents are relatively impatient and/or do not care a lot about the environment and/or Nature regenerates at low rate. We show that the optimal policy of the uncertain problem drives the economy in the long run toward a steady state while, when ignoring irreversibility, the economy follows a balanced growth path accompanied by a perpetual decrease in environmental quality and consumption, both asymptotically converging toward zero. Therefore, accounting for the risk of irreversibility induces more conservative decisions regarding consumption and polluting emissions. In general, however, we cannot rule out situations where the economy will optimally follow an irreversible path and consequently, will also be left, in the long run, with an irreversibly degraded environment.

Lysosomal membrane stability, lipofuscin (LF), malondialdehyde (MDA), neutral lipid (NL) levels, as well as halogenated organic compounds (HOCs), Cr, Cd, Pb and Fe concentrations were analyzed in liver of black-legged kittiwake (BK), herring gull (HG), and northern fulmar (NF) chicks. There were significant species differences in the levels of NL, LF and lysosomal membrane stability. These parameters were not associated with the respective HOC concentrations. LF accumulation was associated with increasing Cr, Cd and Pb concentrations. HG presented the lowest lysosomal membrane stability and the highest. LF and NL levels, which indicated impaired lysosomes in HG compared to NF and BK. Lipid peroxidation was associated with HOC and Fe2+ levels. Specific HOCs showed positive and significant correlations with MDA levels in HG. The study indicates that contaminant exposure can affect lysosomal and lipid associated parameters in seabird chicks even at low exposure levels. These parameters may be suitable markers of contaminant induced stress in arctic seabirds.

This text focuses on the identification, efficiencies, classification and management of landscape features having a potential buffer function regarding diffuse phosphorus, because of their specific structure (vegetation-soil) and of their location at the interface between sources (farm infrastructures, emitting fields…) and surface water bodies. These buffers are very diverse and correspond to natural landscape features (wetlands, riparian areas…) as well as manmade structures (constructed buffer strips or intermediate cases such as field margins, hedgerows). Their role and efficiency depends on the local factors controlling the retention processes (internal organisation and properties of the buffer), on the position within the watershed, and on the landscape context which reciprocally determines the overall buffer capacity of a watershed. On that basis, we recognize the diversity of the buffers in structure and functioning and thus in the way they attenuate the signal, their limitations (sustainability, side effects) and their hierarchic organisation at the watershed scale.

"Could low-level exposure to polluting chemicals be analogous to exercise-a beneficial source of stress that strengthens the body? Some scientists studying the phenomenon of hormesis (beneficial or stimulatory effects caused by low-dose exposure to toxic substances) claim that that this may be the case. IS A LITTLE POLLUTION GOOD FOR YOU? critically examines the current evidence for hormesis. In the process, it highlights the range of methodological and interpretive judgments involved in environmental research: choices about what questions to ask and how to study them, decisions about how to categorize and describe new information, judgments about how to interpret and evaluate ambiguous evidence, and questions about how to formulate public policy in response to debated scientific findings. The book also uncovers the ways that interest groups with deep pockets attempt to influence these scientific judgments for their benefit. Several chapters suggest ways to counter these influences and incorporate a broader array of societal values in environmental research: (1) moving beyond conflict-of-interest policies to develop new ways of safeguarding academic research from potential biases; (2) creating deliberative forums in which multiple stakeholders can discuss the judgments involved in policy-relevant research; and (3) developing ethical guidelines that can assist scientific experts in disseminating debated and controversial phenomena to the public. Kevin C. Elliott illustrates these strategies in the hormesis case, as well as in two additional case studies involving contemporary environmental research: endocrine disruption and multiple chemical sensitivity. This book should be of interest to a wide variety of readers, including scientists, philosophers, policy makers, environmental ethicists and activists, research ethicists, industry leaders, and concerned citizens."--Pub. desc.

Concentrations of POPs in Great skua eggs from Shetland are among the highest in North Atlantic seabirds, with up to 11,600 µg/kg (ww) DDE and up to 17,900 µg/kg ww SumPCB. Concentrations of legacy POPs were significantly lower in 2008 than 1980. Decreases were greatest for least persistent compounds. Median SumPBDEs increased from 99 µg/kg ww in 1980 to 173 µg/kg ww in 2008. There were changes in Great skua breeding season diet, with more adult Herring and Mackerel and less Sandeel. These changes increase exposure to POPs, since Herring and Mackerel accumulate more POPs than Sandeels. In both years, eggs with higher d15N had higher POP concentrations. In 1980, birds feeding more on demersal discard fish from trawl fisheries and less on Sandeels, had higher POP levels in eggs. In 2008, individuals feeding more on Herring and Mackerel, and less on discards, had higher POP levels in eggs.

Dans les bassins versants méditerranéens où les zones cultivées en vigne occupent une part importante de l'espace, les pratiques culturales sont un facteur important d'apparition de risques de pollution diffuse des eaux par les pesticides. Au cours de la thèse, une démarche de modélisation couplée pression-impact a été développée. La question de recherche a porté sur la prise en compte dans le modèle construit de la dynamique des variables d'état du milieu modifiées par les actions culturales. Deux variables ont été identifiées : l'infiltrabilité de la surface du sol et la concentration en matières actives au sol. A l'échelle du bassin versant, pour réaliser l'évaluation des impacts, on s'est appuyé sur l'utilisation du modèle hydrologique distribué MHYDAS qui permet de simuler les flux d'eau et de polluants selon différents scenarii de pratiques et climatiques. Pour représenter la répartition spatio-temporelle des opérations culturales sur chacune des parcelles du bassin versant, le modèle décisionnel DHIVINE a été construit. Il permet de simuler les itinéraires techniques des viticulteurs. Pour chaque exploitation du bassin versant, le modèle est basé sur une représentation de la conduite technique annuelle du vignoble sous forme de plans d'activités. Ces plans mettent en oeuvre des indicateurs d'états de l'agrosystème et prennent en compte les caractéristiques des ressources productives de l'exploitation ainsi que les arbitrages à réaliser entre opérations culturales et parcelles concurrentes. Des modèles biophysiques ont été développés pour simuler les indicateurs de la décision ainsi que l'impact des différentes pratiques sur les états de surface du sol qui conditionnent l'infiltrabilité du sol en surface. Une typologie fonctionnelle des états de surface basée sur leurs propriétés d'infiltrabilité du sol a été utilisée pour développer une démarche visant une modélisation continue dans le temps de l'infiltration. Elle intègre une modélisation parallèle de la dynamique des états de surface du sol nu et du développement de la couverture herbacée par les adventices. Un couplage des modèles a été réalisé sous la plate-forme OpenFLUID. La démarche adoptée ici permet de représenter les dynamiques différentes des variables d'état du milieu en fonction de différentes pratiques culturales et semble adaptée pour l'évaluation des impacts en terme de pollution de l'eau par les pesticides à l'échelle de bassins versants viticoles méditerranéens. | In Mediterranean catchments in which vineyards account for a major share of the area, cropping practices are an important factor with respect to increasing risks of diffuse pesticide pollution of water. This study was about developping an approach for pressure-impact modelling. The research question considered dynamics of agrosystem status variables modified by cropping actions. Two variables were identified : soil surface infiltrability and active material concentration on the soil. On a catchment scale, to assess impacts, we used the distributed hydrological model MHYDAS to simulate water and pollutant flows according to different cropping practice and climatic scenarios. To represent the spatiotemporal distribution of cropping operations on each plot, the decision model DHIVINE was built. It simulates vinegrowers's crop management sequences. For each farm in the catchment, the model is based on a representation of the vineyard annual technical management strategy in the form of activity plans. These plans involve agrosystem status indicators and take into account the characteristics of productive resources on the farm and arbitration between cultivation operations and competing plots. Biophysical models were developped to simulate decision indicators and impacts of cropping practices on soil surface characteristics which are drivers of soil surface infiltrability. A functional typology of soil surface states based on their soil infiltrabilty properties was used to develop an approach for temporally continuous modelling of infiltration. It was based on a parallel modelling of dynamics (i) of soil surface characteristics of bare soil and (ii) of weed cover development. Model coupling was realized with OpenFLUID platform. The approach developped herein allows simulating dynamics of agrosystem status variables as a function of cropping practices. It seems adapted for assessing hydrological impacts at the catchment scale in Mediterranean environments.