title: Effect of Time-Dependent Sorption on the Dissipation of Water-Extractable Pesticides in Soils.
abstract: The dissipation behavior of water-extractable pesticides in soils is important when assessing the phytoavailability of pesticides in soils. This process is less understood than pesticide extraction with organic solvents. To elucidate the dissipation behavior of water-extractable pesticides in soils, we conducted an incubation study using 27 pesticides and five Japanese soils. The rate of decrease of the level of pesticides in water extracts was faster in soils than that of total extracts (water extracts and acetone extracts). This suggests that time-dependent sorption contributed to the difference in the dissipation between the pesticides in water and total extracts from soils. Increased apparent sorption coefficients (Kd,app) with time were positively and significantly correlated with Kd,app values of a 0 day incubation [Kd,app(t0)]. This empirical relationship suggests that Kd,app(t0) values can predict the time-dependent increase in Kd,app and the dissipation of water-extractable pesticides in soils.
authors.affiliation: National Institute for Agro-Environmental Sciences , 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Motoki
authors.affiliation: Food and Agricultural Materials Inspection Center , Agricultural Chemicals Inspection Station, 2-772 Suzuki-cho, Kodaira, Tokyo 187-0011, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Iwafune
authors.affiliation: National Institute for Agro-Environmental Sciences , 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan.
authors.forename: Nobuyasu
authors.initials: N
authors.lastname: Seike
authors.affiliation: National Institute for Agro-Environmental Sciences , 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan.
authors.forename: Keiya
authors.initials: K
authors.lastname: Inao
authors.affiliation: National Institute for Agro-Environmental Sciences , 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Otani
mesh_terms: D000327:Adsorption; D007564:Japan; D007700:Kinetics; D010575:Pesticides / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D010575:Pesticides; D012987:Soil; D012989:Soil Pollutants; D014867:Water
keywords: aging; fate; pesticides; phytoavailability; soil; time-dependent sorption; water extraction