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Exploring how organic matter controls structural transformations in natural aquatic nanocolloidal dispersions

King, Stephen M.; Jarvie, Helen P.. 2012 Exploring how organic matter controls structural transformations in natural aquatic nanocolloidal dispersions. Environmental Science & Technology, 46 (13). 6959-6967. 10.1021/es2034087

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Abstract/Summary

The response of the dispersion nanostructure of surface river bed sediment to the controlled removal and readdition of natural organic matter (NOM), in the absence and presence of background electrolyte, was examined using the technique of small-angle neutron scattering (SANS). Partial NOM removal induced aggregation of the mineral particles, but more extensive NOM removal restored colloidal stability. When peat humic acid (PHA) was added to a NOMdeficient sediment concentration-related structural transformations were observed: at 255 mg/L PHA aggregation of the nanocolloid was actually enhanced, but at 380 mg/L PHA disaggregation and colloidal stability were promoted. The addition of 2 mM CaCl2 induced mild aggregation in the native sediment but not in sediments with added PHA, suggesting that the native NOM and the PHA respond differently to changes in ionic strength. A first attempt at using SANS to directly characterize the thickness and coverage of anadsorbed PHA layer in a natural nanocolloid is also presented. The results are discussed in the context of a hierarchical aquatic colloidal nanostructure, and the implications for contemporary studies of the role of dissolved organic carbon (DOC) in sustaining the transport of colloidal iron in upland catchments.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1021/es2034087
Programmes: CEH Topics & Objectives 2009 onwards > Water
CEH Sections: Acreman
ISSN: 0013-936X
Additional Information. Not used in RCUK Gateway to Research.: This document is the author’s final manuscript version of the journal article, incorporating any revisions agreed during the peer review process. Some differences between this and the publisher’s version remain. You are advised to consult the publisher’s version if you wish to cite from this article. The definitive version is available at www.acs.org
Additional Keywords: organic matter, aquatic, nanocolloidal, NOM, natural organic matter, SANS, small-angle neutron scattering
NORA Subject Terms: Chemistry
Date made live: 10 Oct 2012 15:02
URI: http://nora.nerc.ac.uk/id/eprint/19852

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