Change search
ReferencesLink to record
Permanent link

Direct link
Photochemical and microbial processing of stream and soilwater dissolved organic matter in a boreal forested catchment in northern Sweden
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
2002 (English)In: Aquatic Sciences, ISSN 1015-1621, E-ISSN 1420-9055, Vol. 64, no 3, 269-281 p.Article in journal (Refereed) Published
Abstract [en]

Natural organic matter (NOM) from stream and soil water in a humic-rich headwater catchment in northern Sweden (initial total organic carbon (TOC) concentrations 10-40 mg C L-1) was rapidly degraded by light and microbial activity in an incubation experiment. Concentration losses were 33-50% after 12 days of exposure to 69 W m(-2) artificial PAR and 16 W m(-2) UV radiation. Natural, unshaded mid-day solar radiation in the region (68degreesN 18degreesE) during the month of june is 159 W m(-2) for PAR. In contrast to microbial organic carbon removal, TOC exponentially decreased upon radiation, which suggests that TOC is more rapidly oxidized by light than by ambient microbes. Further, rapid decline in TOC concentration implies the presence of a dominant pool of photo-labile compounds (p > 95%). A measured mass balance for carbon identified 50-75% of the degraded TOC as carbon dioxide after 12 days of exposure to light. The observed conversion of organic to inorganic carbon was accompanied by increases in pH and alkalinity, suggesting that photo-degradation of NOM potentially contributes to in-stream buffering capacity. The remaining refractory TOC changed in chemical character, including an altered molecular weight distribution with decreased average weight and a change in the proportions of humics as evidenced by absorbance ratios (A(254)/A(420)). Extrapolation of the experiment to natural headwater conditions show that photo-degradation is an important in-stream process that should be considered in calculations of carbon turnover in surface waters because of its influence on both TOC amount and character.

Place, publisher, year, edition, pages
2002. Vol. 64, no 3, 269-281 p.
Keyword [en]
photo-degradation, natural organic matter (NOM), headwaters, carbon dioxide, dissolved organic matter (DOM)
URN: urn:nbn:se:umu:diva-50731DOI: 10.1007/s00027-002-8071-zISI: 000179471200004OAI: diva2:467915
Available from: 2011-12-20 Created: 2011-12-20 Last updated: 2011-12-20

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Jonsson, A
By organisation
Department of Ecology and Environmental Sciences
In the same journal
Aquatic Sciences

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

Altmetric score

Total: 18 hits
ReferencesLink to record
Permanent link

Direct link