**Acknowledgements**

practices explain the diffusion of pollution from the soil reservoir: tillage accounts for the vertical distribution of the pollutant, i.e. dilution of the pollutant in the soil profile, and or‐ ganic matter amendments account partially for the availability of the pollutant. In this way, current practices modify the level and volume of polluted soil and the environmental state of the field (surface conditions, OM content, soil profile, etc.), which in turn, influence the fate of the pollutant in the environment. Variability among and within farms also needs to be taken into account by building a farm typology including the general orientations and

Finally, at the regional scale, all these factors combine to determine soil pollution. In the case of CLD, in agreement with the results of physical analyses, andosols, which contain allo‐ phanic clay and have high organic matter content, are the most polluted. In addition, the ef‐ fect of agricultural practices was evidenced by a strong farm effect and an effect of how long

These two aspects (agricultural practices and soil physical properties) proved to be effective in the diagnosis of CLD pollution and in management analysis and could make sense for other forms of agricultural pollution, especially in the case of persistent pesticides. To illus‐ trate this point, the WISORCH model, which accounts for agricultural loads as well as soil and climate characteristics, can simulate changes in soil pollution over time. In the case of CLD contamination, simulation results showed that soils will remain contaminated for six

Wide use of chlorinated pesticides such as chlordecone has led to severe contamination of the environment in the French West Indies. Chlordecone is an organochlorine insecticide that was regularly applied to banana crops more than 20 years ago and is now on the list of POPs prohibited by the Stockholm Convention. Chlordecone is a hydrophobic, non-biode‐ gradable pesticide that is strongly bound to the organic soil matrix which is why soils are still contaminated today. The level of soil pollution and the fate of the pollutant in the eco‐ systems depend on two main determinants at two different scales: agricultural practices and

Obviously, the history of agricultural practices (land-use changes and the intensity of pesti‐ cide use) partly explains soil contamination. The stocks of pesticide still present in soil are important indicators, which calls for the reinforcement of databases on agricultural practi‐ ces, especially on pesticide use. However, soil type mainly explains the concentration of pol‐ lutant in the soil. Our experimental data showed that clay microstructure controls the accumulation of pollutants in the soil and their release into the environment. In the case of andosols, this study revealed the importance of the fractal microstructure and the associated tortuous porosity in trapping the pollutant. Moreover, as chlordecone tends to bind with soil organic matter, the high organic content of tropical volcanic soils also favors its reten‐

hundred years, with andosols decontaminating at a slower rate than other soils.

strategies of the farm and farm practices.

630 Environmental Risk Assessment of Soil Contamination

the land was used for banana cultivation.

the soil physical properties, i.e. the clay microstructure.

**5. Conclusion**

tion.

Funding was provided by the French Chlordecone National Plan ("JAFA" project), the French National Research Agency ("Chlordexco" project) and the French Ministry for Overseas development (MOM).
