We describe the transfer mechanisms of pesticides in hygroscopic soils. The work consisted in using Henry’s constants of five pesticides to study the transfer mechanisms. The numerical work consisted to make a soil sample of height h with initial water content w0 and initial pesticide concentration C0 placing it in an ambient atmosphere
where the temperature and relative humidity are controlled and assumed to be constants. The profiles of concentration as a function of the Henry’s constant of the pesticide for various initial water contents
w0 have been obtained. The results show that for an exposure time of 5 days 18 hours 53 minutes and 20 seconds, the maximum concentration profiles of the pesticide, compared to the initial concentration, represent 0.76% of C0 for trifluralin, 6.4% of C0 for endosulfan, 35.8% of C0 for dichlorvos, 41.2% of C0 for methylparathion and 78.2% of C0 for alachlor. Concerned with those results, we can see that there is a significant increase in transfer mechanisms for high KH and a significant decrease in transfers for low KH . Those results plead in favor of an increased persistence of
pesticides in hygroscopic soils because of their low KH .

hygroscopic soil, transfer mechanisms, pesticides, profiles of concentration