Abstract
The contaminant attenuation in soils is a complex physical, chemical and biological process, which requires an experimental approach for its understanding. Batch experiments were carried out on samples of andisols taken between August and September 2016 from a coffee plantation in Poas de Alajuela to obtain the kF (mg/L) Freundlich constant and the kFoc normalized constant by 0,12 (mode of the existent organic matter fraction), for the substances (kF-kFoc): ametryn 62 - 517; atrazine 18 - 150; bromacil 5.3 - 44; carbaryl 36 - 300; chlorothalonil 45 - 375; hexazinone 3.2 - 27; simazine 5.2 - 43; and terbutryn 60 - 500. The results indicate that between 75 % and 95 % of the mass of the substances is withdrawn from the supernatant aqueous solution and suggest that these soils could reduce a pollutant mass that drags the recharge water by preventing it from reaching the groundwater.