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Modelling flow and inorganic nitrogen dynamics on the Hampshire Avon: Linking upstream processes to downstream water quality

Modelling flow and inorganic nitrogen dynamics on the Hampshire Avon: Linking upstream processes to downstream water quality
Modelling flow and inorganic nitrogen dynamics on the Hampshire Avon: Linking upstream processes to downstream water quality
Managing diffuse pollution in catchments is a major issue for environmental managers planning to meet water quality standards and comply with the EU Water Framework Directive. A major source of diffuse pollution is from nitrogen, with high nitrate concentrations affecting water supplies and in-stream ecology. A dynamic, process based model of flow, nitrate and ammonium (INCA-N) has been applied to the Hampshire Avon as part of the NERC Macronutrient Cycles Programme to link upstream and downstream measurements of water chemistry. The model has been calibrated and validated against Environment Agency discharge and solute chemistry data, as well as a data set collected from a river site immediately upstream of the estuary tidal limit. Upstream measurements of denitrification at six sites have been used to evaluate nitrate removal rates in vegetated and non-vegetated conditions. Results show that sediments underlying vegetation were associated with significantly higher rates of nitrate removal than un-vegetated sediments (with an average increase of 245%). These data have been used to scale up rates of nitrate loss to the whole catchment scale and have been implemented via the model. The effects of streambed geology and macrophyte cover on catchment-scale nitrogen dynamics are explored and nutrient fluxes entering the estuary are evaluated. The model is used to test a strategy for nitrogen reduction assessed using a nitrate vulnerable zone (NVZ) methodology. It suggests that nitrate and ammonium concentrations could be reduced by 10% in 10 years and much lower nitrogen level can be achieved but only over a long time period
Nitrate, Ammonium, Pollution, Denitrification, Rivers, Estuaries
0048-9697
1496-1506
Jin, Li
fb1eef11-3d16-41c1-b9e5-0ff887270f75
Whitehead, Paul G.
5dfb7549-7f3d-4e18-b99b-db00418fdd5c
Heppell, Catherine M.
43d7b090-cdd8-4467-810c-31a07e5b4450
Lansdown, Katrina
fa9ed0c4-76bb-4f6a-9158-9af2f8176119
Purdie, Duncan
18820b32-185a-467a-8019-01f245191cd8
Trimmer, Mark
c5d8598a-d7a3-411f-a380-80498066d88c
Jin, Li
fb1eef11-3d16-41c1-b9e5-0ff887270f75
Whitehead, Paul G.
5dfb7549-7f3d-4e18-b99b-db00418fdd5c
Heppell, Catherine M.
43d7b090-cdd8-4467-810c-31a07e5b4450
Lansdown, Katrina
fa9ed0c4-76bb-4f6a-9158-9af2f8176119
Purdie, Duncan
18820b32-185a-467a-8019-01f245191cd8
Trimmer, Mark
c5d8598a-d7a3-411f-a380-80498066d88c

Jin, Li, Whitehead, Paul G., Heppell, Catherine M., Lansdown, Katrina, Purdie, Duncan and Trimmer, Mark (2016) Modelling flow and inorganic nitrogen dynamics on the Hampshire Avon: Linking upstream processes to downstream water quality. Science of the Total Environment, 572, 1496-1506. (doi:10.1016/j.scitotenv.2016.02.156).

Record type: Article

Abstract

Managing diffuse pollution in catchments is a major issue for environmental managers planning to meet water quality standards and comply with the EU Water Framework Directive. A major source of diffuse pollution is from nitrogen, with high nitrate concentrations affecting water supplies and in-stream ecology. A dynamic, process based model of flow, nitrate and ammonium (INCA-N) has been applied to the Hampshire Avon as part of the NERC Macronutrient Cycles Programme to link upstream and downstream measurements of water chemistry. The model has been calibrated and validated against Environment Agency discharge and solute chemistry data, as well as a data set collected from a river site immediately upstream of the estuary tidal limit. Upstream measurements of denitrification at six sites have been used to evaluate nitrate removal rates in vegetated and non-vegetated conditions. Results show that sediments underlying vegetation were associated with significantly higher rates of nitrate removal than un-vegetated sediments (with an average increase of 245%). These data have been used to scale up rates of nitrate loss to the whole catchment scale and have been implemented via the model. The effects of streambed geology and macrophyte cover on catchment-scale nitrogen dynamics are explored and nutrient fluxes entering the estuary are evaluated. The model is used to test a strategy for nitrogen reduction assessed using a nitrate vulnerable zone (NVZ) methodology. It suggests that nitrate and ammonium concentrations could be reduced by 10% in 10 years and much lower nitrogen level can be achieved but only over a long time period

Text
2015 Avon INCA N_R1_Clean_newFig3.pdf - Accepted Manuscript
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More information

Accepted/In Press date: 22 February 2016
e-pub ahead of print date: 5 March 2016
Published date: 1 December 2016
Keywords: Nitrate, Ammonium, Pollution, Denitrification, Rivers, Estuaries
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 390070
URI: http://eprints.soton.ac.uk/id/eprint/390070
ISSN: 0048-9697
PURE UUID: cb173076-ebb6-4183-8fd4-b2b56842153d
ORCID for Duncan Purdie: ORCID iD orcid.org/0000-0001-6672-1722

Catalogue record

Date deposited: 18 Mar 2016 09:36
Last modified: 08 Jan 2022 07:08

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Contributors

Author: Li Jin
Author: Paul G. Whitehead
Author: Catherine M. Heppell
Author: Katrina Lansdown
Author: Duncan Purdie ORCID iD
Author: Mark Trimmer

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