uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Preferential sequestration of allochthonous organic matter in boreal lake sediments
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
Manuscript (Other academic)
URN: urn:nbn:se:uu:diva-97916OAI: oai:DiVA.org:uu-97916DiVA: diva2:173033
Available from: 2008-12-17 Created: 2008-12-17 Last updated: 2016-03-05Bibliographically approved
In thesis
1. Flocculation of Allochthonous Dissolved Organic Matter – a Significant Pathway of Sedimentation and Carbon Burial in Lakes
Open this publication in new window or tab >>Flocculation of Allochthonous Dissolved Organic Matter – a Significant Pathway of Sedimentation and Carbon Burial in Lakes
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Inland waters receive substantial amounts of organic carbon from adjacent watersheds. Only about half of the carbon exported from inland waters reaches the oceans, while the remainder is lost en route. This thesis identifies flocculation as an important and significant fate of carbon in the boreal landscape. Flocculation reallocates organic carbon from the dissolved state into particles which are prone to settle. Thus, flocculation relocates organic carbon from the water column to the sediment.

The dissolved organic carbon (DOC), mainly originating from terrestrial sources, in a set of Swedish lakes was found to determine the extent of sedimentation of particulate organic carbon. A major fraction of the settling particles were of allochthonous origin. This implies that allochthonous DOC was the precursor of the settling matter in these lakes. The gross sedimentation was of the same magnitude as the evasion of carbon dioxide to the atmosphere.

Sunlight, especially in the photosynthetically active region, stimulated flocculation of DOC. The effect of light appeared to involve a direct photochemical reaction. Iron was involved in the flocculation but it could not be unravelled whether the iron catalyzes the flocculation or just co-precipitates with the settling matter. Microbial activity was identified as the main regulator of the flocculation rates. Accordingly, alteration of temperature, oxygen concentration and pH did not affect flocculation only indirectly, via their effects on microbial metabolism.

A comparison of fluorescence characteristics of organic matter collected in sediment trap and in the sediment surface layer revealed that autochthonous organic carbon was preferentially lost in the sediments while allochthonous matter increased. The recalcitrant nature of the flocculated matter could favour sequestration of this matter in the lake sediment. Hence, the lakes will act as sinks of organic carbon due to a slower mineralization of the flocculated matter in the sediments.

Place, publisher, year, edition, pages
Uppsala: Universitetsbiblioteket, 2008. 42 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 586
flocculation, dissolved organic carbon, allochthonous, carbon sequestration, carbon cycle, boreal lakes
National Category
urn:nbn:se:uu:diva-9500 (URN)978-91-554-7374-7 (ISBN)
Public defence
2009-01-21, Ekmansalen, Kärnhuset, EBC, Norbyvägen 18, Uppsala, 10:00
Available from: 2008-12-17 Created: 2008-12-17 Last updated: 2016-04-28Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Tranvik, Lars
By organisation
Department of Ecology and Evolution

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 147 hits
ReferencesLink to record
Permanent link

Direct link