title: Validation of predicted exponential concentration profiles of chemicals in soils.
abstract: Multimedia mass balance models assume well-mixed homogeneous compartments. Particularly for soils, this does not correspond to reality, which results in potentially large uncertainties in estimates of transport fluxes from soils. A theoretically expected exponential decrease model of chemical concentrations with depth has been proposed, but hardly tested against empirical data. In this paper, we explored the correspondence between theoretically predicted soil concentration profiles and 84 field measured profiles. In most cases, chemical concentrations in soils appear to decline exponentially with depth, and values for the chemical specific soil penetration depth (d(p)) are predicted within one order of magnitude. Over all, the reliability of multimedia models will improve when they account for depth-dependent soil concentrations, so we recommend to take into account the described theoretical exponential decrease model of chemical concentrations with depth in chemical fate studies. In this model the d(p)-values should estimated be either based on local conditions or on a fixed d(p)-value, which we recommend to be 10cm for chemicals with a log K(ow)>3.
authors.affiliation: Department of Environmental Science, Radboud University Nijmegen, Toernooiveld 1, Nijmegen, The Netherlands. a.hollander@science.ru.nl
authors.forename: Anne
authors.initials: A
authors.lastname: Hollander
authors.forename: Iris
authors.initials: I
authors.lastname: Baijens
authors.forename: Ad
authors.initials: A
authors.lastname: Ragas
authors.forename: Mark
authors.initials: M
authors.lastname: Huijbregts
authors.forename: Dik
authors.initials: D
authors.lastname: van de Meent
mesh_terms: D004784:Environmental Monitoring; D008956:Models, Chemical; D012987:Soil / Q000032:analysis; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry; D035501:Uncertainty
chemical_list: D012987:Soil; D012989:Soil Pollutants