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Hakim Abdi. Photo.

Hakim Abdi

Researcher

Hakim Abdi. Photo.

Drought Offsets the Controls on Colored Dissolved Organic Matter in Lakes

Author

  • Enass Said Al-Kharusi
  • Geert Hensgens
  • Abdulhakim M. Abdi
  • Tiit Kutser
  • Jan Karlsson
  • David E. Tenenbaum
  • Martin Berggren

Summary, in English

The concentration of colored dissolved organic matter (CDOM) in lakes is strongly influenced by climate, land cover, and topographic settings, but it is not known how drought may affect the relative importance of these controls. Here, we evaluate the controls of CDOM during two summers with strongly contrasting values of the Palmer drought index (PDI), indicating wet vs. dry conditions. We hypothesized that lake CDOM during a wet summer season is regulated mainly by the surrounding land cover to which the lakes are hydrologically connected, while, during drought, the lakes are disconnected from the catchment and CDOM is regulated by climatic and morphometric factors that govern the internal turnover of CDOM in the lakes. A suite of climate, land cover, and morphometric variables was assembled and used to explain remotely sensed CDOM values for 255 boreal lakes distributed across broad environmental and geographic gradients in Sweden and Norway. We found that PDI explained the variability in CDOM among lakes in a dry year, but not in a wet year, and that severe drought strongly decreased CDOM during the dry year. Large lakes, especially, with a presumed high degree of catchment uncoupling, showed low CDOM during the dry year. However, in disagreement with our hypothesis, climate, land cover, and morphometry all showed a stronger impact on lake CDOM in wet vs. dry years. Thus, drought systematically weakened the predictability of CDOM variations at the same time as CDOM was offset toward lower values. Our results show that drought not only has a direct effect on CDOM, but also acts indirectly by changing the spatial regulation of CDOM in boreal lakes.

Department/s

  • Dept of Physical Geography and Ecosystem Science
  • Centre for Environmental and Climate Science (CEC)
  • BECC: Biodiversity and Ecosystem services in a Changing Climate
  • Biodiversity and Conservation Science
  • MECW: The Middle East in the Contemporary World
  • Centre for Advanced Middle Eastern Studies (CMES)
  • LU Profile Area: Nature-based future solutions

Publishing year

2024

Language

English

Publication/Series

Remote Sensing

Volume

16

Issue

8

Document type

Journal article

Publisher

MDPI AG

Topic

  • Environmental Sciences

Keywords

  • boreal lakes
  • coloured dissolved organic matter (CDOM)
  • drought
  • Palmer drought index (PDI)
  • remote sensing data
  • spatial variables

Status

Published

Research group

  • Biodiversity and Conservation Science

ISBN/ISSN/Other

  • ISSN: 2072-4292