@article{fdi:010092285,
  title = {{T}ransport and sorption of 2,4-dichlorophenoxyacetic acid in allophanic soils},
  author = {{M}ueller, {K}. and {D}uwig, {C}{\'e}line},
  editor = {},
  language = {{ENG}},
  abstract = {{F}ield applications of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-{D}) are commonly formulated as esters, amine salts, or alkali, but studies on the environmental impact focus on the 2,4-{D} acid form. {W}e hypothesized that the formulation would affect its transport. {T}o better understand 2,4-{D} transport through allophanic soils, leaching experiments with 2,4-{D} acetic acid, 2,4-{D} ethylhexyl ester, and tritium were conducted in 100 mm of repacked soil columns. {T}hree of the four silt loam soils were allophanic. {T}he 2,4-{D} sorption isotherms and kinetics of sorption were determined from batch experiments. {T}he symmetrical tritium breakthrough curves ({BTC}s) showed that water transport was in physical equilibrium, and these were used to estimate the dispersivity of the soils. {T}ritium was not inert in the allophanic soils. {T}he {BTC}s of both 2,4-{D} formulations were shifted to the right of tritium and showed extended tailing characteristic typical for sorption nonequilibrium. {T}he 2,4-{D} {BTC}s were successfully fit with a two-site chemical nonequilibrium model. {B}atch and leaching experiments showed the sorption of 2,4-{D} ethylhexyl ester to be higher and characterized by stronger nonequilibrium than 2,4-{D} acetic acid sorption in all soils. {T}he sorption coefficient values derived from the {BTC}s were higher than those from 24-h batch experiments. {F}or the two allophanic topsoils, the predicted ester {BTC}s were significantly worse when using the independently derived {K}-d compared with the {BTC}s using the fitted {K}-d. 2,4-{D} sorption was correlated to p{H} and organic matter content. {T}ransport of 2,4-{D} was slower than expected in the allophanic soils and was attributed to retention of dissociated 2,4-{D} by positively charged soil surfaces.},
  keywords = {2,4 {D} ; nonequilibrium transport ; tritium ; allophanic soil},
  booktitle = {},
  journal = {{S}oil {S}cience},
  volume = {172},
  numero = {5},
  pages = {333--348},
  ISSN = {0038-075{X}},
  year = {2007},
  DOI = {10.1097/{SS}.0b013e31803bbb85},
  URL = {https://www.documentation.ird.fr/hor/fdi:010092285},
}