Newbould, R.A. orcid.org/0000-0001-8256-7307, Powell, D.M., Hodges, J. et al. (3 more authors) (2025) Channel geometry controls on chemical behavior in rivers: insights from a comparative field study. ACS ES&T Water. ISSN: 2690-0637
Abstract
Microbially mediated transformations, such as nitrification and biodegradation, play a crucial role in removing pollutants from rivers. Although in-stream removal rate coefficients are often assumed to be spatially and temporally constant, they are likely affected by the channel shape and size because these factors control contact between the water column and fixed biofilms. Here, we test the hypothesis that transformation rate constants are inversely proportional to the hydraulic radius (R: ratio of the channel cross-sectional area to wetted perimeter) in dye tracing experiments conducted in two U.K. rivers with contrasting morphologies: (1) the River Maun (shallow: mean bankfull R = 1.25 m) and (2) the River Calder (deep: mean bankfull R = 3 m). In each case, a slug of rhodamine WT was injected upstream of a wastewater outfall, and samples were collected downstream, staggered by the rhodamine travel time. Rate constants were derived for sucralose, ammonium, caffeine, and linear alkylbenzenesulfonate. Sucralose (persistent, hydrophilic, and exclusively of wastewater origin) was used as a conservative tracer to adjust model fits for dilution. Higher rate coefficients were observed for all biotransformed pollutants in the Maun compared to the Calder, supporting the hypothesis and highlighting the need to consider geomorphology in models of chemical behavior.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2025 The Authors. This publication is licensed under CC-BY 4.0 - https://creativecommons.org/licenses/by/4.0/ |
Keywords: | wastewater; dye tracing; geomorphology; chemical exposure; biodegradation; nitrification |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > School of Mechanical, Aerospace and Civil Engineering |
Funding Information: | Funder Grant number ENGINEERING AND PHYSICAL SCIENCE RESEARCH COUNCIL EP/P012027/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 26 Sep 2025 10:47 |
Last Modified: | 26 Sep 2025 10:47 |
Status: | Published online |
Publisher: | American Chemical Society (ACS) |
Refereed: | Yes |
Identification Number: | 10.1021/acsestwater.4c01203 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:232146 |