Determining patterns in the composition of dissolved organic matter in fresh waters according to land use and management

Christopher A Yates*, Penny J Johnes, F.L. Brailsford, Chris D. Evans, Richard P Evershed, H.C. Glanville, Davey Jones, Charlotte E M Lloyd, Miles Marshall, Alun T Owen

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

2 Citations (Scopus)
82 Downloads (Pure)

Abstract

In freshwaters, the origins of dissolved organic matter (DOM) have been found to exert a fundamental control on its reactivity, and ultimately, its ecosystem functional role. A detailed understanding of landscape scale factors that control the export of DOM to aquatic ecosystems is, therefore, pivotal if the effects of DOM flux to freshwaters are to be fully understood. In this study we present data from a national sampling campaign across the United Kingdom in which we explore the variability in DOM composition in three broad landscape types defined by similar precipitation, geology, land use and management, hydrology, and nutrient enrichment status. We characterised samples from fifty-one sites, grouping them into one of three major underlying classifications: circumneutral streams underlain by clay and mudstone (referred to as ‘clay’), alkaline streams underlain by Cretaceous Chalk or by Carboniferous or Jurassic Limestone (‘limestone’), and acidic streams in peatland catchments underlain by a range of low permeability lithologies (‘peat’). DOM composition was assessed through organic matter stoichiometry (organic carbon: organic nitrogen; organic carbon: organic phosphorus; C/N(P)DOM) and metrics derived from ultra-violet (UV)/ visible spectroscopic analysis of DOM such as specific UV absorption (a254 nm; SUVA254). We found similar SUVA254, C/NDOM and DOM/a254 relationships within classifications, demonstrating that despite a large degree of heterogeneity within environments, catchments with shared environmental character and anthropogenic disturbance export DOM with a similar composition and character. Improving our understanding of DOM characterisation is important for helping predict shifts in stream ecosystem function, and ecological responses to enrichment or mitigation efforts and how these may result in species composition shifts and biodiversity loss in freshwater ecosystems.
Original languageEnglish
JournalBiogeochemistry
Early online date29 Aug 2022
DOIs
Publication statusE-pub ahead of print - 29 Aug 2022

Bibliographical note

Funding Information:
This study was supported by Natural Environment Research Council (Grant No. NE/K010689/1).

Publisher Copyright:
© 2022, The Author(s).

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