TY - JOUR

T1 - Parameterization and regionalization of Cd sorption characteristics of sandy soils. II. Regionalization

T2 - Freundlich k estimates by pedotransfer functions

AU - Springob, Günther

AU - Böttcher, Jürgen

N1 - Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 1998

Y1 - 1998

N2 - 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).

AB - 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).

KW - Cadmium

KW - Freundlich

KW - Multiple regression

KW - Sorption

UR - http://www.scopus.com/inward/record.url?scp=0005752782&partnerID=8YFLogxK

U2 - 10.1002/jpln.1998.3581610613

DO - 10.1002/jpln.1998.3581610613

M3 - Article

AN - SCOPUS:0005752782

VL - 161

SP - 689

EP - 696

JO - Journal of Plant Nutrition and Soil Science

JF - Journal of Plant Nutrition and Soil Science

SN - 1436-8730

IS - 6

ER -