title: Prediction of the adsorption of ionizable pesticides in soils.
abstract: Adsorption of six acidic and four basic pesticides was measured in nine temperate soils. In general, sorption of acids was weak as compared to bases and followed the order dicamba<metsulfuron-methyl<fluazifop-P<metribuzin<2,4-D<flupyrsulfuron-methyl<fluroxypyr<terbutryn<pirimicarb<fenpropimorph. Adsorption was negatively correlated with soil pH and positively correlated with organic carbon content. Statistical analysis against a wide range of soil and pesticide descriptors was used to identify the best combination of properties that describes the variation in adsorption. A regression equation including Log D (lipophilicity corrected for pH), the soil organic carbon content, and a pesticide descriptor (related to the van der Waals volume) was selected to predict the adsorption of acids (r2=72.1% on an independent dataset). The behavior of bases was more complex, and approaches specific to each compound seem to be required.
authors.affiliation: Environment Department, University of York, Heslington, York, YO10 5DD, United Kingdom. m.kah@csl.gov.uk
authors.forename: Melanie
authors.initials: M
authors.lastname: Kah
authors.forename: Colin D
authors.initials: CD
authors.lastname: Brown
mesh_terms: D000143:Acids / Q000737:chemistry; D000327:Adsorption; D000704:Analysis of Variance; D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000737:chemistry; D010575:Pesticides / Q000737:chemistry*; D012987:Soil / Q000032:analysis*
chemical_list: D000143:Acids; D007477:Ions; D010575:Pesticides; D012987:Soil