Parameterization and regionalization of Cd sorption characteristics of sandy soils. II. Regionalization

Freundlich k estimates by pedotransfer functions

verfasst von: Günther Springob, Jürgen Böttcher
Abstract: The aim was to describe Cd sorption in spatially variable sandy soils of the 'Fuhrberger Feld' catchment area as a prerequisite for prognosis of Cd transport in soil and of the threat of groundwater pollution. Thus, the possibility is evaluated to derive a generalized Freundlich equation based on multiple regressions relating the retention parameters k and M (from isotherm data of part I of this study) to basic soil properties (pedotransfer functions). For the parameter M (exponent), the correlation 'measured vs estimated' was weak (r² < 0.5) whereas k was well predictable by pedotransfer functions. The best regression was obtained if organic carbon (OC), clay content and H⁺ activity were combined as independent variables (r² up to 0.96). The obtained k values were much higher than those from comparable literature models, probably due to lower ionic strength and different composition of our background solutions used for the isotherms. As a critical evaluation, the estimates for k were used to derive solute Cd concentrations (C_est) which then were compared to measured data (range 0.1-3 μg L^-1). The best but still unsatisfactory- r² was 0.77, obtained if C_est was compared to Cd in 0.01 M_c Ca(NO₃)₂ equilibria (Cd₀). Cd in fresh soil solution (Cd_z) showed no significant correlation with C_est, except for one relationship where OC had been excluded from the preceding multiple regression of k. Generally, the role of the variable OC remained unclear. Direct multiple regressions of measured solute Cd vs soil properties (bypassing k, no sorbed fraction) yielded much closer correlations, with r² = 0.9 for Cd₀ vs OC, H⁺ activity, clay (log data, OC decreases C) and r² = 0.7 for Cd₂ vs OC, H⁺ activity, clay (log data, OC enhances C).
Organisationseinheit(en): Institut für Bodenkunde
AG Bodenbiophysik
Typ: Artikel
Journal: Journal of Plant Nutrition and Soil Science
Band: 161
Seiten: 689-696
Anzahl der Seiten: 8
ISSN: 1436-8730
Publikationsdatum: 1998
Publikationsstatus: Veröffentlicht
Peer-reviewed: Ja
ASJC Scopus Sachgebiete: Bodenkunde, Pflanzenkunde
Elektronische Version(en): https://doi.org/10.1002/jpln.1998.3581610613 (Zugang: Unbekannt)

BibTeX

@article{fd3cf4ff65404fb484fb2854b8628758,
title = "Parameterization and regionalization of Cd sorption characteristics of sandy soils. II. Regionalization: Freundlich k estimates by pedotransfer functions",
abstract = "The aim was to describe Cd sorption in spatially variable sandy soils of the 'Fuhrberger Feld' catchment area as a prerequisite for prognosis of Cd transport in soil and of the threat of groundwater pollution. Thus, the possibility is evaluated to derive a generalized Freundlich equation based on multiple regressions relating the retention parameters k and M (from isotherm data of part I of this study) to basic soil properties (pedotransfer functions). For the parameter M (exponent), the correlation 'measured vs estimated' was weak (r2 < 0.5) whereas k was well predictable by pedotransfer functions. The best regression was obtained if organic carbon (OC), clay content and H+ activity were combined as independent variables (r2 up to 0.96). The obtained k values were much higher than those from comparable literature models, probably due to lower ionic strength and different composition of our background solutions used for the isotherms. As a critical evaluation, the estimates for k were used to derive solute Cd concentrations (Cest) which then were compared to measured data (range 0.1-3 μg L-1). The best but still unsatisfactory- r2 was 0.77, obtained if Cest was compared to Cd in 0.01 Mc Ca(NO3)2 equilibria (Cd0). Cd in fresh soil solution (Cdz) showed no significant correlation with Cest, except for one relationship where OC had been excluded from the preceding multiple regression of k. Generally, the role of the variable OC remained unclear. Direct multiple regressions of measured solute Cd vs soil properties (bypassing k, no sorbed fraction) yielded much closer correlations, with r2 = 0.9 for Cd0 vs OC, H+ activity, clay (log data, OC decreases C) and r2 = 0.7 for Cd2 vs OC, H+ activity, clay (log data, OC enhances C).",
keywords = "Cadmium, Freundlich, Multiple regression, Sorption",
author = "G{\"u}nther Springob and J{\"u}rgen B{\"o}ttcher",
note = "Copyright: Copyright 2020 Elsevier B.V., All rights reserved.",
year = "1998",
doi = "10.1002/jpln.1998.3581610613",
language = "English",
volume = "161",
pages = "689--696",
journal = "Journal of Plant Nutrition and Soil Science",
issn = "1436-8730",
publisher = "Wiley-VCH Verlag",
number = "6",
}