Brailsford, FL, Glanville, HC ORCID: https://orcid.org/0000-0002-8192-6678, Marshall, MR, Yates, CA, Owen, AT, Golyshin, PN, Johnes, PJ and Jones, DL (2021) Land cover and nutrient enrichment regulates low-molecular weight dissolved organic matter turnover in freshwater ecosystems. Limnology and Oceanography.

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Abstract

Dissolved organic matter (DOM) is a complex mixture of carbon-containing compounds. The low-molecular weight (LMW) fraction constitutes thousands of different compounds and represents a substantial proportion of DOM in aquatic ecosystems. The turnover rates of this LMW DOM can be extremely high. Due to the challenges of measuring this pool at a molecular scale, comparatively little is known of the fate of LMW DOM compounds in lotic systems. This study addresses this knowledge gap, investigating the microbial processing of LMW DOM across 45 sites representing a range of physicochemical gradients and dominant land covers in the United Kingdom. Radioisotope tracers representing LMW dissolved organic carbon (DOC) (glucose), dissolved organic nitrogen (DON) (amino acid mixture), dissolved organic phosphorus (DOP) (glucose-6-phosphate), and soluble reactive phosphorus (SRP, measured as orthophosphate) were used to measure the microbial uptake of different DOM compounds in river waters. The amount of DOM biodegradation varied between different components (DON ≥ DOC > DOP), with the rate of turnover of all three increasing along a gradient of N and P enrichment across the range of sites. Conversely, the uptake of SRP decreased along this same gradient. This was ascribed to preferential utilization of DOP over SRP. Dominant land cover had a significant effect on DOM use as a resource, due to its control of nutrient enrichment within the catchments. We conclude that nutrient enrichment of river waters will lead to further DOM removal from the water column, increased microbial growth, and a decrease in stream oxygen saturation, exacerbating the effects of eutrophication in rivers.

Item Type: Article
Additional Information: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Uncontrolled Keywords: freshwater; ecosystems
Subjects: G Geography. Anthropology. Recreation > G Geography (General)
Divisions: Faculty of Natural Sciences > School of Geography, Geology and the Environment
Related URLs:
Depositing User: Symplectic
Date Deposited: 02 Jul 2021 07:48
Last Modified: 14 Jul 2021 13:43
URI: https://eprints.keele.ac.uk/id/eprint/9775

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