**2.4. Influence of allophane on the decontamination process**

Soil features influence pollutant availability and hence natural decontamination of the soil. In the case of CLD and other organochlorine pesticides, natural decontamination is very slow, and pollution management and remediation have to take into account any soil proper‐ ties that could influence the efficiency of the treatment considered [1].

Although different strategies are proposed in the literature to remediate diffuse pollution of CLD including phytoextraction [29] and microbial degradation [30, 31], to date, these ap‐ proaches have not been very successful. Recently "In situ chemical reduction" was tested for the reduction of the pesticide in the soil [32], but the technique was clearly less efficient in soils containing allophane clay. Six months of in situ chemical reduction resulted in an 88% decrease in CLD content in halloysite soils but only in a 47% decrease in allophanic soils. The efficiency of the in situ chemical reduction technique was probably affected by poor ac‐ cessibility to the allophane clusters. Trapping thus likely reduces the degradation of pesti‐ cides in andosols. Whatever the soil decontamination process used to desorb or degrade the CLD, the confining structure of the clay has to be taken into account to ensure the process is effective.
