title: Biodegradation, sorption, and transport of 2,4-dichlorophenoxyacetic acid in saturated and unsaturated soils.
abstract: The fate of an organic contaminant in soil depends on many factors, including sorption, biodegradation, and transport. The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) was used as a model compound to illustrate the impact of these interacting factors on the fate of an organic contaminant. Batch and column experiments performed with a sandy loam soil mixture under saturated and unsaturated conditions were used to determine the effects of sorption and biodegradation on the fate and transport of 2,4-D. Sorption of 2,4-D was found to have a slight but significant effect on transport of 2,4-D under saturated conditions (retardation factor, 1.8) and unsaturated conditions (retardation factor, 3.4). Biodegradation of 2,4-D was extensive under both batch and column conditions and was found to have a significant impact on 2,4-D transport in column experiments. In batch experiments, complete mineralization of 2,4-D (100 mg kg-1) occurred over a 4-day period following a 3-day lag phase under both saturated and unsaturated conditions. The biodegradation rate parameters calculated for batch experiments were found to be significantly different from those estimated for column experiments.
authors.affiliation: Department of Soil and Water Science, University of Arizona, Tucson 85721.
authors.forename: M R
authors.initials: MR
authors.lastname: Estrella
authors.forename: M L
authors.initials: ML
authors.lastname: Brusseau
authors.forename: R S
authors.initials: RS
authors.lastname: Maier
authors.forename: I L
authors.initials: IL
authors.lastname: Pepper
authors.forename: P J
authors.initials: PJ
authors.lastname: Wierenga
authors.forename: R M
authors.initials: RM
authors.lastname: Miller
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000378:metabolism* / Q000493:pharmacokinetics; D000327:Adsorption; D001673:Biodegradation, Environmental; D001692:Biological Transport; D012987:Soil; D012988:Soil Microbiology
chemical_list: D012987:Soil; D015084:2,4-Dichlorophenoxyacetic Acid