The water budget of soil, the uptake in plants and the leaching to groundwater of cadmium (Cd) and lead (Pb) were simulated simultaneously using a physiological plant uptake model and a tipping buckets water and solute transport model for soil. Simulations were compared to results from a ten-year experimental field study, where four organic amendments were applied every second year. Predicted concentrations slightly decreased (Cd) or stagnated (Pb) in control soils, but increased in amended soils by about 10% (Cd) and 6% to 18% (Pb). Estimated plant uptake was lower in amended plots, due to an increase of Kd (dry soil to water partition coefficient). Predicted concentrations in plants were close to measured levels in plant residues (straw), but higher than measured concentrations in grains. Initially, Pb was mainly predicted to deposit from air into plants (82% in 1998); the next years, uptake from soil became dominating (30% from air in 2006), because of decreasing levels in air. For Cd, predicted uptake from air into plants was negligible (1–5%).
La formation, sous l'action d'un champ magnétique quantifiant, d'un état lié à un centre donneur dans un semiconducteur dopé constitue un bon exemple de transition isolant-métal dans lequel les corrélations électroniques et le désordre jouent à la fois un rôle important dans le mécanisme de conduction. L'utilisation d'une méthode variationnelle (énergie de l'état lié) permet de calculer la variation de la concentration en porteurs libres en fonction du champ magnétique et de la température et de la comparer aux résultats expérimentaux. En particulier, il est possible de calculer les conditions d'apparition du régime d'énergie d'activation de conductivité (concentration en impuretés, champ magnétique)
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