UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

Influence of Pleistocene glacial deposits on the transport of agricultural nitrate in the river Wensum catchment, UK

Hiscock, Kevin M; Cooper, Richard J; Lewis, Melinda A; Gooddy, Daren C; Howson, Thomas J; Wexler, Sarah K; (2024) Influence of Pleistocene glacial deposits on the transport of agricultural nitrate in the river Wensum catchment, UK. Journal of Hydrology , 633 , Article 130982. 10.1016/j.jhydrol.2024.130982. Green open access

[thumbnail of Hiscock et al_JoH_2024.pdf]
Preview
Text
Hiscock et al_JoH_2024.pdf - Published Version

Download (7MB) | Preview

Abstract

Mitigating NO3− pollution requires an understanding of the hydrological processes controlling contaminant mobilisation and transport, particularly in agricultural catchments underlain by Pleistocene glacial deposits. Focusing on the Wensum catchment in East Anglia, UK, precipitation (n = 20), stream water (n = 50), field drainage (n = 22) and groundwater (n = 84) samples collected between February–March 2011 and April–September 2012 were variously analysed for water stable isotopes (δ2HH2O and δ18OH2O), the dual-isotopes of NO3− (δ15NNO3 and δ18ONO3), groundwater residence time indicators (CFCs and SF6) and hydrochemical parameters. The residence time indicators suggested a component of modern (post-1960) groundwater throughout the sequence of glacial deposits that corresponds with the penetration of agricultural NO3−. Denitrification and lower NO3− concentrations (<8 mg L−1) are observed in the glacial tills, compared with higher NO3− concentrations (<90 mg L−1) observed under more oxidising conditions in the glacial sands and gravels. Storm hydrograph separation for two storms in April and September 2012 using two- and three-component mixing models showed a faster response with field drainage (36–38 %) and baseflow (5–37 %) contributing to the total stream discharge in areas of clay loam soils over glacial tills. In these areas, the dual stable isotopes of NO3− (δ15NNO3 = +11.8 ‰ and δ18ONO3 = +7.1 ‰) indicated a denitrified source of nitrogen from field drainage and groundwater. In comparison, a dampened response and a higher percentage of baseflow (29–80 %) was observed in areas of sandy clay loam soils over glacial sands and gravels. In these areas, mean NO3− isotopic signatures (δ15NNO3 = +7.8 ‰ and δ18ONO3 = +5.0 ‰) indicated a source of nitrified NH4+. In conclusion, understanding hydrological processes in catchments underlain by variable glacial deposits can inform nutrient management plans and cultivation practices to reduce the risk of agricultural NO3− contamination.

Type: Article
Title: Influence of Pleistocene glacial deposits on the transport of agricultural nitrate in the river Wensum catchment, UK
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.jhydrol.2024.130982
Publisher version: http://dx.doi.org/10.1016/j.jhydrol.2024.130982
Language: English
Additional information: Copyright © 2024 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Keywords: Pleistocene glacial deposits; Agriculture; Groundwater nitrate; Stable isotopes; Groundwater residence time indicators; Storm hydrograph separation
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL SLASH
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS > Institute of Archaeology
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS > Institute of Archaeology > Institute of Archaeology Gordon Square
URI: https://discovery.ucl.ac.uk/id/eprint/10189291
Downloads since deposit
3Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item