title: Differences in sorption behavior of the herbicide 4-chloro-2-methylphenoxyacetic acid on artificial soils as a function of soil pre-aging.
abstract: OBJECTIVE
  The sorption behavior of the herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA) to three different artificial soil mixtures was investigated. Artificial soils serve as model systems for improving understanding of sorption phenomena.
  
  
  METHODS
  The soils consisted of quartz, ferrihydrite, illite, montmorillonite, and charcoal. In a previous study, several selected mixtures had been inoculated with organic matter, and microbial aging (incubation) had been performed for different periods of time (3, 12, and 18 months) before conducting the sorption experiments. The effect of this pre-incubation time on the sorption behavior was determined. Interaction of MCPA with soil surfaces was monitored by aqueous phase sorption experiments, using high-performance liquid chromatography/ultraviolet and in selected cases Fourier-transformed infrared spectroscopy.
  
  
  CONCLUSIONS
  The sorption behavior showed large differences between differently aged soils; Freundlich and linear sorption model fits (with sorption constantsKf, 1/nexponents, andKdvalues, respectively) were given for pH = 3 and the unbuffered pH of ∼7. The largest extent of sorption from diluted solutions was found on the surfaces with a pre-incubation time of 3 months. Sorption increased at acidic pH values.
  
  
  CONCLUSIONS
  Regarding the influence of aging of artificial soils, the following conclusions were drawn: young artificial soils exhibit stronger sorption at lower concentrations, with a largerKfvalue than aged soils. A correlation with organic carbon content was not confirmed. Thus, the sorption characteristics of the soils are more influenced by the aging of the organic carbon than by the organic carbon content itself.
authors.affiliation: Health and Environment Department, AIT Austrian Institute of Technology GmbH, Konrad-Lorenz-Strasse 24, 3430 Tulln, Austria.
authors.forename: Georg
authors.initials: G
authors.lastname: Waldner
authors.affiliation: Health and Environment Department, AIT Austrian Institute of Technology GmbH, Konrad-Lorenz-Strasse 24, 3430 Tulln, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Friesl-Hanl
authors.affiliation: Institute of Soil Research, University of Natural Resources and Life Sciences, Peter-Jordan-Strasse 82, 1190 Vienna, Austria.
authors.forename: Georg
authors.initials: G
authors.lastname: Haberhauer
authors.affiliation: Institute of Soil Research, University of Natural Resources and Life Sciences, Peter-Jordan-Strasse 82, 1190 Vienna, Austria.
authors.forename: Martin H
authors.initials: MH
authors.lastname: Gerzabek
keywords: Artificial soils; FTIR; Incubation time; MCPA; Soil components; Sorption