Combined Size and Density Fractionation of Soils for Investigations of Organo-Mineral Interactions

Details

Serval ID
serval:BIB_A00A0B9B5292
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Combined Size and Density Fractionation of Soils for Investigations of Organo-Mineral Interactions
Journal
Journal of Visualized Experiments
Author(s)
Viret Fanny, Grand Stephanie
ISSN
1940-087X
Publication state
Published
Issued date
15/02/2019
Peer-reviewed
Oui
Number
144
Pages
e58927
Language
english
Abstract
Combined size and density fractionation (CSDF) is a method used to physically separate soil into fractions differing in particle size and mineralogy. CSDF relies on sequential density separation and sedimentation steps to isolate (1) the free light fraction (uncomplexed organic matter), (2) the occluded light fraction (uncomplexed organic matter trapped in soil aggregates) and (3) a variable number of heavy fractions (soil minerals and their associated organic matter) differing in composition. Provided that the parameters of the CSDF (dispersion energy, density cut-offs, sedimentation time) are properly selected, the method yields heavy fractions of relatively homogeneous mineral composition. Each of these fractions is expected to have a different complexing ability towards organic matter, rendering this a useful method to isolate and study the nature of organo-mineral interactions. Combining density and particle size separation brings an improved resolution compared to simple size or density fractionation methods, allowing the separation of heavy components according to both mineralogy and size (related to surface area) criteria. As is the case for all physical fractionation methods, it may be considered as less disruptive or aggressive than chemically-based extraction methods. However, CSDF is a time-consuming method and furthermore, the quantity of material obtained in some fractions can be limiting for subsequent analysis. Following CSDF, the fractions may be analyzed for mineralogical composition, soil organic carbon concentration and organic matter chemistry. The method provides quantitative information about organic carbon distribution within a soil sample and brings light to the sorptive capacity of the different, naturally-occurring mineral phases, thus providing mechanistic information about the preferential nature of organo-mineral interactions in soils (i.e., which minerals, what type of organic matter).
Keywords
Soil organic matter, organo-mineral complexes, heavy fraction, occluded fraction, free light fraction, organic carbon stabilization, sodium polytungstate, soil mineralogy, oxides, silicates
Pubmed
Web of science
Create date
15/04/2019 13:48
Last modification date
21/08/2019 6:17
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