Change search
ReferencesLink to record
Permanent link

Direct link
Depth-dependent molecular composition and photo-reactivity of dissolved organic matter in a boreal lake under winter and summer conditions
University of Maryland, MD 20688 USA .
German Research Centre Environm Heatlh, Germany .
Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
2013 (English)In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 10, no 11, 6945-6956 p.Article in journal (Refereed) Published
Abstract [en]

Transformations of dissolved organic matter (DOM) in boreal lakes lead to large greenhouse gas emissions as well as substantial carbon storage in sediments. Using novel molecular characterization approaches and photochemical degradation experiments we studied how seasonal patterns in water column stratification affected the DOM in a Swedish lake under early spring and summer conditions. Dissolved organic carbon (DOC) concentrations were consistently higher above the sediment when compared to surface waters throughout the sampling periods. Photobleaching alone could not explain this difference in DOC because the lake was covered by 40 cm-thick ice during late winter sampling and still showed the same DOC trend. The differences in the molecular diversity between surface DOM in winter and summer were consistent with ongoing photobleaching/ decarboxylation and a possible bacterial consumption of photo-products. Additional photo-degradation experiments using simulated sunlight showed a production of highly oxidized organic molecules and low molecular weight compounds in all late winter samples and also in the deep water sample in summer. In the surface summer DOM sample, few such molecules were produced during the photo-degradation experiments, confirming that DOM was already photobleached prior to the experiments. This study suggests that photobleaching, and therefore also the ice cover during winter, plays a central role in surface DOM transformation, with important differences in the molecular composition of DOM between surface and deep boreal lake waters. The release of DOC from boreal lake sediments also contribute to this pattern. Photochemical degradation of DOM may be more extensive following ice-out and water column turnover when non-light exposed and thereby photosensitive DOM is photo-mineralized. Hence, the yearly DOM photo-mineralization may be greater than inferred from studies of recently light-exposed DOM.

Place, publisher, year, edition, pages
European Geosciences Union (EGU) / Copernicus Publications , 2013. Vol. 10, no 11, 6945-6956 p.
National Category
Earth and Related Environmental Sciences
URN: urn:nbn:se:liu:diva-102793DOI: 10.5194/bg-10-6945-2013ISI: 000327814700013OAI: diva2:683850

Funding Agencies|Linkoping University||Swedish research councils VR and Formas||

Available from: 2014-01-07 Created: 2013-12-26 Last updated: 2015-03-12

Open Access in DiVA

fulltext(4527 kB)107 downloads
File information
File name FULLTEXT01.pdfFile size 4527 kBChecksum SHA-512
Type fulltextMimetype application/pdf

Other links

Publisher's full text

Search in DiVA

By author/editor
Bastviken, David
By organisation
Department of Water and Environmental StudiesFaculty of Arts and Sciences
In the same journal
Earth and Related Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar
Total: 107 downloads
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

Altmetric score

Total: 193 hits
ReferencesLink to record
Permanent link

Direct link