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Drought Offsets the Controls on Colored Dissolved Organic Matter in Lakes

Al-Kharusi, Enass Said LU ; Hensgens, Geert LU ; Abdi, Abdulhakim M. LU orcid ; Kutser, Tiit ; Karlsson, Jan ; Tenenbaum, David E. LU and Berggren, Martin LU (2024) In Remote Sensing 16(8).
Abstract

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... (More)

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.

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author
; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
boreal lakes, coloured dissolved organic matter (CDOM), drought, Palmer drought index (PDI), remote sensing data, spatial variables
in
Remote Sensing
volume
16
issue
8
article number
1345
publisher
MDPI AG
external identifiers
  • scopus:85191368488
ISSN
2072-4292
DOI
10.3390/rs16081345
language
English
LU publication?
yes
id
03b0ea9f-a551-4049-a59d-896ce433ff4b
date added to LUP
2024-05-07 14:50:05
date last changed
2024-05-08 02:17:05
@article{03b0ea9f-a551-4049-a59d-896ce433ff4b,
  abstract     = {{<p>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.</p>}},
  author       = {{Al-Kharusi, Enass Said and Hensgens, Geert and Abdi, Abdulhakim M. and Kutser, Tiit and Karlsson, Jan and Tenenbaum, David E. and Berggren, Martin}},
  issn         = {{2072-4292}},
  keywords     = {{boreal lakes; coloured dissolved organic matter (CDOM); drought; Palmer drought index (PDI); remote sensing data; spatial variables}},
  language     = {{eng}},
  number       = {{8}},
  publisher    = {{MDPI AG}},
  series       = {{Remote Sensing}},
  title        = {{Drought Offsets the Controls on Colored Dissolved Organic Matter in Lakes}},
  url          = {{http://dx.doi.org/10.3390/rs16081345}},
  doi          = {{10.3390/rs16081345}},
  volume       = {{16}},
  year         = {{2024}},
}