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Related to ancient industrial activities and growing recycling of residual organic products from urban origin, persistent organic compounds among which Polycyclic Aromatic Hydrocarbons (PAH) are found in soils. A better management of polluted sites and an evaluation of the risks associated with PAH in the environment both require a better knowledge of their fate in the soil : transport, retention, dissipation. Flexible models incorporating the processes known to control the behaviour of the PAH in the soil are required for (1) evaluation against data sets and (2) for carrying out long term simulations to evaluate the fate of PAH. Our study proposes the development and the use of an interdisciplinary model applicable in the field and coupling the various processes determining the fate of PAH in soils. This model was developed with the VSoil modelling platform of INRA (/The-Project). The model uses modules already developed for water flow, heat transport, solute transport and organic matter decomposition. New modules were developed for the adsorption, and degradation of the PAH. The model was calibrated in the field using parameters obtained in laboratory experiments and on a specific short experiment in the field. Next, the model was tested and validated against data obtained in the field on a long period. Last, the model was used to test various scenario corresponding to climate change, frequency of organic products application, and various hypothesis of PAH availability. Our results show that the model is able to reproduce the observations for a wide range of conditions ranging from highly contaminated industrial sites to agricultural fields receiving organic residual products and with low level of contamination.

Thesis defended May 5, 2017