Brownification on hold: What traditional analyses miss in extended surface water records

Abstract

Widespread increases in organic matter (OM) content of surface waters, as measured by color and organic carbon (OC), are a major issue for aquatic ecosystems. Long-term monitoring programs revealed the issue of "browni-fication", with climate change, land cover changes and recovery from acidification all suspected to be major drivers or contributing factors. While many studies have focused on the impact and drivers, fewer have followed up on whether brownification is continuing. As time-series of OM data lengthen, conventional data-analysis approaches miss important information on when changes occur. To better identify temporal OM patterns during three decades (1990-2020) of systematic monitoring, we used generalized additive models to analyze 164 time-series from watercourses located across Sweden. Increases in OC that were widespread during 1990-2010 ceased a decade ago, and most color increases ceased 20 years ago. These findings highlight the need to reassess the understanding of brownification's spatial and temporal extent, as well as the tools used to analyze lengthening time series.

Keywords

Brownification; Organic matter; Absorbance; Watercourses; Long-term trends; Generalized additive mixed model

Published in

Water Research
2021, volume: 203, article number: 117544
Publisher: PERGAMON-ELSEVIER SCIENCE LTD

SLU Authors

• Eklöf, Karin

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

• von Brömssen, Claudia

  • Department of Energy and Technology, Swedish University of Agricultural Sciences
    

• Amvrosiadi, Nino

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    
  • RISE Research Institutes of Sweden

• Fölster, Jens

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

• Wallin, Marcus

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

• Bishop, Kevin

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

Associated SLU-program

Lakes and watercourses

Global goals (SDG)

SDG14 Life below water

UKÄ Subject classification

Oceanography, Hydrology, Water Resources

Publication identifier

• DOI: https://doi.org/10.1016/j.watres.2021.117544

Permanent link to this page (URI)

https://res.slu.se/id/publ/113761