Predicting the transfer of contaminants in soils is often hampered by lacking validation of mathematical models. Here, we applied Hydrus-2D software to three agricultural soils for simulating the 1900–2005 changes of zinc and lead concentration profiles derived from industrial atmospheric deposition, to validate the tested models with plausible assumptions on past metal inputs to reach the 2005 situation. The models were set with data from previous studies on the geochemical background, estimated temporal metal deposition, and the 2005 metal distributions. Different hypotheses of chemical reactions of metals with the soil solution were examined: 100% equilibrium or partial equilibrium, parameterized following kinetic chemical extractions. Finally, a two-site model with kinetic constant values adjusted at 1% of EDTA extraction parameters satisfactory predicted changes in metal concentration profiles for two arable soils. For a grassland soil however, this model showed limited applicability by ignoring the role of earthworm activity in metal incorporation.

Non-point source pollution is a cause of major concern within the European Union. This is reflected in increasing public and political focus on a more sustainable use of pesticides, as well as a reduction in diffuse pollution. Climate change will likely to lead to an even more intensive use of pesticides in the future, affecting agriculture in many ways. At the same time, the Water Framework Directive (WFD) and associated EU policies called for a “good” ecological and chemical status to be achieved for water bodies by the end of 2015, currently delayed to 2021–2027 due to a lack of efficiency in policies and timescale of resilience for hydrosystems, especially groundwater systems. Water managers need appropriate and user-friendly tools to design agro-environmental policies. These tools should help them to evaluate the potential impacts of mitigation measures on water resources, more clearly define protected areas, and more efficiently distribute financial incentives to farmers who agree to implement alternative practices. At present, a number of reports point out that water managers do not use appropriate information from monitoring or models to make decisions and set environmental action plans. In this paper, we propose an integrated and collaborative approach to analyzing changes in land use, farming systems, and practices and to assess their effects on agricultural pressure and pesticide transfers to waters. The integrated modeling of agricultural scenario (IMAS) framework draws on a range of data and expert knowledge available within areas where a pesticide action plan can be defined to restore the water quality, French “Grenelle law” catchment areas, French Water Development and Management Plan areas, etc. A so-called “reference scenario” represents the actual soil occupation and pesticide-spraying practices used in both conventional and organic farming. A number of alternative scenarios are then defined in cooperation with stakeholders, including socio-economi

Predicting the transfer of contaminants in soils is often hampered by lacking validation of mathematical models. Here, we applied Hydrus-2D software to three agricultural soils for simulating the 1900–2005 changes of zinc and lead concentration profiles derived from industrial atmospheric deposition, to validate the tested models with plausible assumptions on past metal inputs to reach the 2005 situation. The models were set with data from previous studies on the geochemical background, estimated temporal metal deposition, and the 2005 metal distributions. Different hypotheses of chemical reactions of metals with the soil solution were examined: 100% equilibrium or partial equilibrium, parameterized following kinetic chemical extractions. Finally, a two-site model with kinetic constant values adjusted at 1% of EDTA extraction parameters satisfactory predicted changes in metal concentration profiles for two arable soils. For a grassland soil however, this model showed limited applicability by ignoring the role of earthworm activity in metal incorporation.

The paper presents theoretical model of the pollutant density changes in water environment. Spreading of the pollutant is modeled by strong pointed force on the pollution system in the water. This force appears as a strong short term pressure in certain point of the system after which it starts to move in one direction. Results of applying of this model shows that density of the pollution depends on mass of the pollution and the speed of the spreading of the pollutant in the aquatic system. One dimensional result of the pollutant density that is received, i.e. pointed direction of the pollutant stands only in the cases of precisely fixed conditions defined by modeling. For any other values that exceed these values the pollutant density value is equivalent zero value.

Le cycle de l’azote est aujourd’hui, à l’échelle de la planète, le plus profondément perturbé des grands cycles biogéochimiques. L’azote qui entre à 80 % dans la composition de l’atmosphère se transforme en nitrates dans les sols. Une partie de ces nitrates est ensuite entraînée vers les eaux de surface et souterraines. Ce phénomène – absolument naturel – a été fortement amplifié par l’utilisation d’engrais de synthèse depuis le milieu du XXe siècle. Cinquante ans plus tard, la pollution croissante de nos ressources en eaux est devenue un souci majeur et pas seulement parce que la France est menacée de lourdes sanctions par la Commission européenne. Le bassin de la Seine est particulièrement exposé à la pollution par les nitrates, les cultures céréalières et industrielles y étant très développées. Or le bassin compte de nombreux aquifères qui alimentent une large population. Avant même de penser à satisfaire en 2015 la Directive cadre européenne en atteignant le bon état écologique des eaux, il faudrait réussir à stopper l’aggravation de la pollution nitrique. C’est bien sûr l’objectif des décideurs du bassin qui ont néanmoins besoin de savoir comment agir efficacement. Là interviennent les chercheurs. En étudiant de façon aussi fine que possible la diffusion de l’azote et des nitrates vers les aquifères (par l’observation de terrain et l’utilisation de modèles informatiques), ceux-ci contribuent à mesurer l’évolution de la pollution et à proposer des stratégies pour la limiter. Des scénarios sont ensuite testés. La « directive nitrates » de 1991 a abouti à la distinction entre zones dites « normales » et zones « vulnérables ». En « zones vulnérables », le non respect des prescriptions légales du code « de bonnes pratiques agricoles » est passible de sanctions financières. Encore faut-il que les mesures préconisées, fertilisation raisonnée, mise en place de bandes enherbées et d’inter-cultures de type CIPAN (cultures intermédiaires pièges à nitrates), soient efficaces. Les recherches permettent à la fois de le vérifier et de les optimiser. Reste que la propagation des nitrates dans le sol et les aquifères est par essence très lente… Des mesures d’urgence s’imposent en sachant que l’on n’a que trop tardé à les mettre en place et que leur effet sera long à se faire sentir