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Reactivity of dissolved organic matter in response to acid deposition

Author:
  • Sara M. Ekström
  • Margareta Sandahl
  • Anders Nilsson
  • Dan B. Kleja
  • Emma S. Kritzberg
Publishing year: 2016-07-01
Language: English
Pages: 463-475
Publication/Series: Aquatic Sciences
Volume: 78
Issue: 3
Document type: Journal article
Publisher: Birkhaüser

Abstract english

Fluvial export of organic matter from the terrestrial catchment to the aquatic system is a large and increasing carbon flux. The successful reduction in sulfuric acid deposition since the 1980s has been shown to enhance the mobility of organic matter in the soil, with more terrestrially derived dissolved organic matter (DOM) reaching aquatic systems. Changes in soil acidity also affect the quality of the DOM. In this study we explore the consequences this may have on the reactivity and turnover of the terrestrially derived DOM as it reaches the aquatic system. DOM of different quality (estimated by absorbance, fluorescence and size exclusion chromatography) was produced through extraction of boreal forest O-horizon soils from podzol at two sulfuric acid concentrations corresponding to natural throughfall in spruce forest in Southern Sweden around 1980 and today. Extraction was done using two different methods, i.e. field leaching and laboratory extraction. The DOM extracts were used to assess if differences in acidity generate DOM of different reactivity. Three reactivity experiments were performed: photodegradation by UV exposure, biodegradation by bacteria, and biodegradation after UV exposure. Reactivity was assessed by measuring loss of dissolved organic carbon and absorbance, change in fluorescence and molecular weight, and bacterial production. DOM extracted at lower sulfuric acid concentration was more susceptible to photooxidation, and less susceptible to bacterial degradation, than DOM extracted at a higher sulfuric acid concentration. Thus the relative importance of these two turnover processes may be altered with changes in acid deposition.

Keywords

  • Oceanography, Hydrology, Water Resources
  • Biodegradation
  • Carbon cycling
  • Decreasing acidification
  • DOM quality
  • Photooxidation

Other

Published
  • ISSN: 1015-1621
Anders Nilsson
E-mail: anders [dot] nilsson [at] biol [dot] lu [dot] se

Professor

Aquatic ecology

+46 46 222 83 65

+46 70 346 25 66

E-D130

50

Research group

Aquatic Ecology

Projects

Doctoral students and postdocs

Main supervisor

Varpu Pärssinen

Assistant supervisor

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