The adsorption and degradation of chlorpyriphos-methyl, pendimethalin and metalaxyl in solid urban waste compost

To evaluate the feasibility of using compost to prepare substrates for the disposal of pesticide residues, adsorption and degradationstudies were carried out on three widely used agricultural pesticides: chlorpyriphos-methyl, pendimethalin and metalaxyl. Obtainedfrom solid urban waste, this compost has been shown to be able to adsorb high levels of chlorpyriphos-methyl and pendimethalin (85%, 100 %) whereas metalaxyl was only adsorbed at a level of 37 %. However, adding smectite to the compost increased the adsorptionof metalaxyl by 117 %. Chlorpyriphos-methyl and pendimethalin degraded quickly with half-lives of 1.7 and 14.5 days, respectively,whereas metalaxyl proved more persistent (a half-life of 84 days). Adding ammonium nitrate to the compost accelerated metalaxyldegradation to a half-life of 15 days.