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Metal sorption to Spodosol Bs horizons: Organic matter complexes predominate

Tiberg, Charlotta and Sjöstedt, Carin and Gustafsson, Jon Petter (2018). Metal sorption to Spodosol Bs horizons: Organic matter complexes predominate. Chemosphere. 196, 556-565
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Official URL: https://doi.org/10.1016/j.chemosphere.2018.01.004

Abstract

While metal sorption mechanisms have been studied extensively for soil surface horizons, little information exists for subsoils, for example Spodosol Bs horizons. Here the sorption of cadmium(10, copper(II) and lead(II) to seven Bs horizons from five sites was studied. Extended X-ray absorption fine structure (EXAFS) spectroscopy showed that cadmium(II) and lead(II) were bound as inner-sphere complexes to organic matter. Addition of o-phosphate (to 1 mu mol l(-1)) did not result in any significant enhancement of metal sorption, nor did it influence EXAFS speciation. An assemblage model using the SHM and CD-MUSIC models overestimated metal sorption for six out of seven soil samples. To agree with experimental results, substantial decreases (up to 8-fold) had to be made for the fraction 'active organic matter', f(Hs), while the point-of-zero charge (PZC) of ferrihydrite had to be increased. The largest decreases of f(HS) were found for the soils with the lowest ratio of pyrophosphate-to oxalate-extractable Al (Al-pyp/Al-ox), suggesting that in these soils, humic and fulvic acids were to a large extent inaccessible for metal sorption. The low reactivity of ferrihydrite towards lead(II) can be explained by potential spillover effects from co-existing allophane, but other factors such as ferrihydrite crystallisation could not be ruled out. In conclusion, organic matter was the predominant sorbent for cadmium(II), copper(II) and lead(II). However, for lead(II) the optimised model suggests additional, but minor, contributions from Fe (hydr) oxide surface complexes. These results will be important to correctly model metal sorption in spodic materials.

Authors/Creators:Tiberg, Charlotta and Sjöstedt, Carin and Gustafsson, Jon Petter
Title:Metal sorption to Spodosol Bs horizons: Organic matter complexes predominate
Series/Journal:Chemosphere (0045-6535)
Year of publishing :2018
Volume:196
Page range:556-565
Number of Pages:10
Publisher:Elsevier
ISSN:0045-6535
Language:English
Publication Type:Journal article
Refereed:Yes
Article category:Scientific peer reviewed
Version:Published version
Full Text Status:Public
Agris subject categories.:P Natural resources > P30 Soil science and management
X Agricola extesions > X50 Chemistry
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Soil Science
Keywords:Cadmium, Copper, Lead, Soil, EXAFS, Assemblage model
URN:NBN:urn:nbn:se:slu:epsilon-e-4800
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-4800
ID Code:15351
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Dept. of Soil and Environment
(S) > Dept. of Soil and Environment
Deposited By: SLUpub Connector
Deposited On:12 Mar 2018 07:21
Metadata Last Modified:12 Mar 2018 07:21

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