title: Adsorption-desorption studies of alachlor, metolachlor, EPTC, chlorothalonil and pirimiphos-methyl in contrasting soils.
abstract: Five soils with different organic matter contents ranging from 0.48 to 10.4% were used to study the adsorption and desorption of alachlor, metolachor, EPTC, chlorothalonil and pirimiphos-methyl in batch experiments. The isotherm shapes according to Giles classification were S-type for alachlor, metolachlor and chlorothalonil, changing to L-type for the latter as the level of soil organic matter increased, and L-type for EPTC and pirimiphos-methyl. The adsorption isotherms fitted the Freundlich equation x/m = KfCe1/n. The Kf values increased with the increase of organic matter content. The amounts of pesticides adsorbed over a range of concentrations of 0.1-20 mg litre-1 reached 63.1% for alachlor, 69.2% for metolachlor, 89.3% for EPTC, 98.4% for chlorothalonil and 96.3% for pirimiphos-methyl. The increase of the amounts desorbed with acetone indicated that the sorption of organic compounds onto organic matter occurred principally via weak London-type induction forces, or dispersion forces which are characteristics of the physical adsorption process.
authors.affiliation: Department of Chemistry, University of Ioannina, Ioannina 45110, Greece.
authors.forename: Georgios
authors.initials: G
authors.lastname: Patakioutas
authors.forename: Triantafyllos A
authors.initials: TA
authors.lastname: Albanis
mesh_terms: D000081:Acetamides / Q000378:metabolism; D000096:Acetone / Q000494:pharmacology; D000327:Adsorption / Q000187:drug effects; D000465:Algorithms; D006115:Greece; D007700:Kinetics; D009570:Nitriles / Q000378:metabolism; D009946:Organothiophosphorus Compounds / Q000378:metabolism; D010575:Pesticides / Q000378:metabolism*; D012987:Soil / Q000032:analysis; D012989:Soil Pollutants / Q000378:metabolism*; D013859:Thiocarbamates / Q000378:metabolism
chemical_list: D000081:Acetamides; D009570:Nitriles; D009946:Organothiophosphorus Compounds; D010575:Pesticides; D012987:Soil; D012989:Soil Pollutants; D013859:Thiocarbamates; D000096:Acetone; C000188:alachlor; C014153:pirimiphos methyl; C005806:tetrachloroisophthalonitrile; C036251:EPTC; C051786:metolachlor