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Binding of metals to macromolecular organic acids in natural waters

does organic matter?

van Schaik, Joris W. J. (2008). Binding of metals to macromolecular organic acids in natural waters. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880 ; 2008:72
ISBN 978-91-86195-05-2
[Doctoral thesis]

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Abstract

Trace metal speciation and bioavailability have become keys to current day toxicity and risk assessments. For many metals, macromolecular organic acids constitute the major ligand in fresh water and soil solution. Therefore, understanding their characteristics and behaviour is necessary for understanding trace metal behaviour. This study comprises investigations of the proton- and copper-binding properties of hydrophobic and hydrophilic dissolved organic matter fractions, and competition effects of iron(III) and aluminium. The solutions studied were a forest floor solution and a municipal solid waste incinerator bottom ash leachate. Two geochemical models (SHM and NICA-Donnan) were tested and calibrated against the experimental data. A structural analysis of the binding mode of iron(III) to fulvic acid in acid aqueous solutions was made using extended X-ray absorption fine structure (EXAFS) spectroscopy. Dissolved organic carbon (DOC) in the bottom ash leachate had fulvic acid-like properties and was dominated by the hydrophilic acid fraction. Three organic fractions (hydrophobic, transphilic and hydrophilic) were isolated from the forest floor solution using an XAD-8/XAD-4 tandem. All fractions were characterised by distinct but differing proton-binding properties, suggesting a more acidic character than 'generic' fulvic acid. The copper-binding isotherms were very similar for all three fractions and suggested strong copper binding to a small number of sites. In general, both models tested could be adjusted to obtain good fits to data on both proton- and copper-binding, but iron(III) and aluminium competition was better predicted by the SHM than the NICA-Donnan model. Only mononuclear iron(III) complexes were included in the model calculations, as the EXAFS study showed that these ¬dominated in the aqueous phase. Studies on untreated soil solution indicated that the three isolated fractions were the only contributors to the observed copper binding and together constitute the 'active' DOC fraction. Thus, combination of Leenheer fractionation data with the model parameters derived in this study is recommended for improved predictions of trace metal speciation in soil solutions. However, further studies along this research line, including other samples and trace metals, are highly recommended.

Authors/Creators:van Schaik, Joris W. J.
Title:Binding of metals to macromolecular organic acids in natural waters
Subtitle:does organic matter?
Year of publishing :2008
Volume:2008:72
Number of Pages:72
Papers/manuscripts:
NumberReferences
ALLI. van Schaik, J.W.J., Persson, I., Kleja, D.B., Gustafsson, J.P. (2008). EXAFS study on the reactions between iron and fulvic acid in acid aqueous solutions. Environmental Science & Technology 42(7), 2367-2373. II. Olsson, S., van Schaik, J.W.J., Gustafsson, J.P., Kleja, D.B., van Hees, P.A.W. (2007). Copper(II) binding to dissolved organic matter fractions in municipal solid waste incinerator bottom ash leachate. Environmental Science & Technology 41(12), 4286-4291. III. van Schaik, J.W.J., Kleja, D.B., Gustafsson, J.P. Acid-Base and copper-binding properties of three organic matter fractions isolated from a forest floor soil solution (manuscript). IV. van Schaik, J.W.J., Olsson, S., Kleja, D.B., Gustafsson, J.P. Copper- binding properties of total and hydrophilic organic matter in a forest floor soil solution (manuscript).
Place of Publication:Uppsala
ISBN for printed version:978-91-86195-05-2
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:metallic elements, trace elements, copper, heavy metals, toxicity, organic acids, soil ph, water resources, humus, models
Keywords:trace metal, humic substance, DOC, EXAFS, copper, heavy metal, hydrophobic, hydrophilic, MSWI, metal toxicity
URN:NBN:urn:nbn:se:slu:epsilon-2516
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-2516
ID Code:1818
Department:(NL, NJ) > Dept. of Soil and Environment
(S) > Dept. of Soil and Environment
Deposited By: Joris van Schaik
Deposited On:19 Sep 2008 00:00
Metadata Last Modified:02 Dec 2014 10:14

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