Dissolved Organic Matter from a colloidal perspective
(2023)- Abstract
- Dissolved organic matter (DOM) is considered the most bioavailable fraction of soil, and thus play a key role in the cycling of carbon. Because of its mobility, DOM also forms the connection between terrestrial and aquatic systems, and constitutes an important vector for nutrients and contaminants. DOM is in this thesis operationally defined as the organic matter in an aqueous solution which is not retained upon filtration using a pore size of 0.2μm. This means that DOM is a heterogeneous mixture of different chemical components, ranging in size from small molecules up to colloidal particles of a few hundred nanometres.
In this thesis, we have characterised DOM from the molecular to colloidal length scale, using a combination of... (More) - Dissolved organic matter (DOM) is considered the most bioavailable fraction of soil, and thus play a key role in the cycling of carbon. Because of its mobility, DOM also forms the connection between terrestrial and aquatic systems, and constitutes an important vector for nutrients and contaminants. DOM is in this thesis operationally defined as the organic matter in an aqueous solution which is not retained upon filtration using a pore size of 0.2μm. This means that DOM is a heterogeneous mixture of different chemical components, ranging in size from small molecules up to colloidal particles of a few hundred nanometres.
In this thesis, we have characterised DOM from the molecular to colloidal length scale, using a combination of spectroscopy, microscopy and scattering techniques. The DOM was obtained by extraction of soil from the organic
layer of a boreal spruce forest. We found that the dominant chemical component of DOM was carbohydrates, and that about half of the organic carbon was present in colloidal form. The structure of the DOM colloids depended on the extraction procedure used. Large dense aggregates observed at room temperature and below could be dispersed into smaller components by increasing the temperature or pH. Additionally, we studied the bacterial decomposition of DOM and found that the colloidal fraction remained intact, while small molecules were readily decomposed. We have also assessed interactions between DOM and hematite nanoparticles, using neutron scattering. Here, we found that the low molecular weight fraction of DOM induces charge reversal and aggregation of the hematite particles. Our combined results show that the colloidal fraction of DOM needs to be considered when assessing DOM bioavailability and mobility. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/1b325e56-e48b-425a-b9c4-9967b236440e
- author
- Andersson, Erika LU
- supervisor
-
- Ulf Olsson LU
- Per Persson LU
- Anders Tunlid LU
- opponent
-
- Professor Richtering, Walter, Aachen University
- organization
- publishing date
- 2023-05
- type
- Thesis
- publication status
- published
- subject
- keywords
- dissolved organic matter, colloids, Microbial decomposition, hematite nanoparticles, soil, small angle scattering, light scattering, 1H NMR
- pages
- 221 pages
- publisher
- Lund University, Faculty of Science
- defense location
- KC:A, Kemicentrum hörsal A.
- defense date
- 2023-06-09 09:15:00
- ISBN
- 978-91-7422-956-1
- 978-91-7422-957-8
- project
- Structure and Dynamics of Natural Colloids
- language
- English
- LU publication?
- yes
- id
- 1b325e56-e48b-425a-b9c4-9967b236440e
- date added to LUP
- 2023-05-02 11:30:31
- date last changed
- 2023-09-01 17:10:15
@phdthesis{1b325e56-e48b-425a-b9c4-9967b236440e,
abstract = {{Dissolved organic matter (DOM) is considered the most bioavailable fraction of soil, and thus play a key role in the cycling of carbon. Because of its mobility, DOM also forms the connection between terrestrial and aquatic systems, and constitutes an important vector for nutrients and contaminants. DOM is in this thesis operationally defined as the organic matter in an aqueous solution which is not retained upon filtration using a pore size of 0.2μm. This means that DOM is a heterogeneous mixture of different chemical components, ranging in size from small molecules up to colloidal particles of a few hundred nanometres.<br/><br/>In this thesis, we have characterised DOM from the molecular to colloidal length scale, using a combination of spectroscopy, microscopy and scattering techniques. The DOM was obtained by extraction of soil from the organic<br/>layer of a boreal spruce forest. We found that the dominant chemical component of DOM was carbohydrates, and that about half of the organic carbon was present in colloidal form. The structure of the DOM colloids depended on the extraction procedure used. Large dense aggregates observed at room temperature and below could be dispersed into smaller components by increasing the temperature or pH. Additionally, we studied the bacterial decomposition of DOM and found that the colloidal fraction remained intact, while small molecules were readily decomposed. We have also assessed interactions between DOM and hematite nanoparticles, using neutron scattering. Here, we found that the low molecular weight fraction of DOM induces charge reversal and aggregation of the hematite particles. Our combined results show that the colloidal fraction of DOM needs to be considered when assessing DOM bioavailability and mobility.}},
author = {{Andersson, Erika}},
isbn = {{978-91-7422-956-1}},
keywords = {{dissolved organic matter; colloids; Microbial decomposition; hematite nanoparticles; soil; small angle scattering; light scattering; 1H NMR}},
language = {{eng}},
publisher = {{Lund University, Faculty of Science}},
school = {{Lund University}},
title = {{Dissolved Organic Matter from a colloidal perspective}},
url = {{https://lup.lub.lu.se/search/files/145657510/ErikaAndersson_kappa.pdf}},
year = {{2023}},
}