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Molybdenum binding to soil constituents in acid soils

an XAS and modelling study

Gustafsson, Jon-Petter and Tiberg, Charlotta (2015). Molybdenum binding to soil constituents in acid soils. Chemical Geology. 417, 279-288
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Official URL: http://dx.doi.org/10.1016/j.chemgeo.2015.10.016

Abstract

Despite its importance as a trace element, the binding mechanisms of molybdenum in soils are not well known. In this study, we studied the binding of molybdenum onto selected soil samples, and we used X-ray absorption spectroscopy (XAS) to characterize the coordination of molybdenum on three important environmental sorbents: ferrihydrite (Fh), amorphous aluminium hydroxide (Al(OH)(3)) and fulvic acid. The X-ray near-edge structure (XANES) data showed that the added molybdenum(VI) was not reduced, although for the organic samples the coordination shifted from tetrahedral to octahedral. The EXAFS (extended X-ray absorption fine structure) analysis showed that molybdenum(VI) on Fh and Al(OH)(3) was dominated by edge-sharing bidentate complexes with Mo center dot center dot center dot Fe and Mo center dot center dot center dot Al distances of 2.80 and 2.62 angstrom, respectively. For ferrihydrite, there was a minor contribution from a corner-sharing bidentate complex at 3.55 angstrom. Further, geochemical modelling suggested an additional role of an outer-sphere complex at high pH. A sample from a spodic Bs horizon had XANES and EXAFS features similar to those of Mo sorbed to Al(OH)(3), highlighting the importance of Al(OH)(3)-type sorbents in this soil. However, in the studied organic samples molybdenum(VI) was present in a distorted octahedral configuration as an organic complex. The results were used to improve molybdenum binding reaction equilibrium constants in the CD-MUSIC model for ferrihydrite and in the Stockholm Humic Model. Collectively the results show that acid soils may contain sorbents able to bind molybdenum efficiently, and thus prevent its leaching to waters. (C) 2015 Elsevier B.V. All rights reserved.

Authors/Creators:Gustafsson, Jon-Petter and Tiberg, Charlotta
Title:Molybdenum binding to soil constituents in acid soils
Subtitle:an XAS and modelling study
Series/Journal:Chemical Geology (0009-2541)
Year of publishing :2015
Depositing date:17 December 2015
Volume:417
Page range:279-288
Number of Pages:10
Publisher:Elsevier
ISSN:0009-2541
Language:English
Publication Type:Journal article
Refereed:Yes
Article category:Scientific peer reviewed
Version:Accepted version
Full Text Status:Public
Agris subject categories.:P Natural resources > P33 Soil chemistry and physics
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Geochemistry
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Soil Science
Agrovoc terms:molybdenum, soil chemicophysical properties, sorption
Keywords:Molybdate, Ferrihydrite, Aluminium hydroxide, Soils, Organic, Matter, Complexation
URN:NBN:urn:nbn:se:slu:epsilon-e-3140
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-3140
Additional ID:
Type of IDID
Web of Science (WoS)000365098800023
DOI10.1016/j.chemgeo.2015.10.016
ID Code:12910
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:17 Dec 2015 15:06
Metadata Last Modified:09 Oct 2017 23:15

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