International audience | Estimates of standing biomass and fluxes of biomass in a mixed-deciduous woodland were derived, and used with results for concentrations of seven polycyclic aromatic hydrocarbons (PAHs) in different compartments of the woodland system to quantitatively assess some of the key fluxes and burdens of PAHs in this complex system. We quantified PAH burdens in air, in leaves of three deciduous tree species, in leaf litter and in soil, and uptake of PAHs by the tree leaves; PAH fluxes in litterfall, and deposition to the litter layer on the woodland floor during winter were calculated from these data. Air burdens exhibited marked seasonal variations for all compounds, with lowest values in summer when combustion-related emissions were low. Leaves did not accumulate large burdens of PAHs while on the trees and consequently, litterfall-associated fluxes of PAHs were small, representing only a fraction of the burdens in the litter layer to which they were deposited. Higher PAH burdens in air in winter, combined with the organic-matter-rich nature of the litter layer, are thought to be responsible for fluxes of PAHs to the litter layer in winter being 20–170 times the peak litterfall fluxes. The soil compartment was calculated to contain 25 years' worth of deposition of benzo[ghi]perylene, the most recalcitrant PAH in this study. Storage quotients for fluoranthene, pyrene, benzo[k]fluoranthene and benzo[a]pyrene burdens in soil represented 7–10 years' worth of deposition, while fluorene and phenanthrene storage in soil approached unity with inputs (1 and 3 years' worth of deposition, respectively). The relative importance of storage and loss processes was therefore closely related to the physico-chemical properties of the PAH, and is discussed in relation to the cycling of carbon in the woodland.

Rising concern about agricultural non-print water pollution has led to the proposal of many regulatory measures. Agri-environmental programmes have been implemented in the different EU Member States according to the Commission regulation 2078/92. Best management practices, one of the most popular tools, have rarely been assessed in a fully satisfying way. Therefore, the main objective of this project is to provide planners in charge of the implementation of BMPs in the field of combating diffusion pollution either at a national or local scale, with both a guideline allowing the definition of critical areas on which efforts should be place in priority, and a selection grid permitting the assessment of BMPs in a three-dimensional space defined by environmental effectiveness, associated economic costs and social acceptability by farmers and land managers. Expectedd results should contribute to help Member States choosing the most appropriate measures and ways for an efficient implementation of BMPs, with the support of scientifically validated technical and economic recommendations. | Le principal objectif de ce projet est de procurer aux acteurs responsables de la lutte contre la pollution diffuse grâce aux meilleures pratiques de gestion une échelle nationale ou locale qui indique les zones prioritaires et l'évaluation des méthodes par l'efficacité environnementale, les coûts économiques associés et l'acceptation sociale de la part des agriculteurs et des gestionnaires des terres.