Soil interfaces in a changing world

The context of this study is the pollution of soils and water by a persistent organo-chlorinated insecticide, chlordecone, in a tropical environment. The application of chlordecone to control the banana black weevil has led to continuing diffuse pollution of soils, and to its being a source of contamination for cultivated plants, as well as for terrestrial and marine ecosystems. Chlordecone is toxic and stable and is considered to be a persistent organic pesticide. Consequently, the amounts of chlordecone that could migrate through the environment and contaminate agricultural products need to be controlled. We measured the impact of two composts (5% weight) on chlordecone sequestration in andosols. To this end, we first characterized the transfer of chlordecone from soil to water, and then its transfer from soil to plants. After 3 months of maturation, soil-water and soil-plant transfers were reduced by a factor of from 3 to 10. We also showed that adding compost to contaminated soils increases chlordecone sequestration because it leads to changes in soil microstructure in the form of pore collapse and closure of the fractal structure of the allophane content