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The relative contribution of sewage and diffuse phosphorus sources in the River Avon catchment, southern England: Implications for nutrient management

The relative contribution of sewage and diffuse phosphorus sources in the River Avon catchment, southern England: Implications for nutrient management
The relative contribution of sewage and diffuse phosphorus sources in the River Avon catchment, southern England: Implications for nutrient management

In order to effectively manage nutrient river load reductions and target remediation strategies, it is important to determine the relative contributions of diffuse and point sources across the river catchment. This study used a geographical information system (GIS) to apply phosphorus (P) export coefficients (obtained from the literature) to 58 water quality monitoring sites across a large, urbanised, mixed land use catchment, typical of southern lowland England (the River Avon, Warwickshire, UK). These coefficients were used to estimate the annual P load at each monitoring site, and also the relative contribution of point source (from sewage treatment works (STW)) and diffuse input (from both livestock and agricultural land use). The estimated annual P loads showed very close agreement (r2=0.98) with the measured total phosphorus (TP) loads. Sites with the highest proportion of P derived from STW had the highest TP concentrations and loads, and also had greater variations between seasons, with elevated P concentrations occurring during the summer months. The GIS model was re-run to determine the effect of an 80% reduction in P output from STW serving over 10 000 people, thereby assessing the effect of implementing the European Union's Urban Waste Water Treatment Directive (UWWTD). The exported TP load was reduced by 52%, but the sites with the highest TP concentrations were still those with the highest proportion of P derived from STW. The GIS model was re-run to estimate the impact of 80% P reductions at a further 11 STW of varying sizes. This reduced the total TP load by only 29 tonnes year-1, but greatly reduced the P concentrations in many highly nutrient contaminated tributaries. The number of sites with P concentrations greater than 1 mg l-1 was cut from 15 (before UWWTD implementation) to 2. These findings suggest that after UWWTD implementation, resources should focus on introducing tertiary sewage treatment at the remaining large STW, before targeting diffuse inputs. This conclusion is also likely to apply to other lowland river catchments in southern England, most of which have similar population densities to the River Avon.

Export coefficients, GIS, Nitrogen, Nutrient reduction, Phosphorus, Urban Waste Water Treatment Directive
0048-9697
67-81
Bowes, Michael J.
9da246ca-0f05-4027-bb4f-dffa5f0debc7
Hilton, John
afa149ac-c1a8-4275-99df-28b1e2d067c9
Irons, Gordon P.
1241ce3c-c418-47a1-958f-c830923014cb
Hornby, Duncan D.
75cfaf57-72c1-4392-a78c-89b4b1033dca
Bowes, Michael J.
9da246ca-0f05-4027-bb4f-dffa5f0debc7
Hilton, John
afa149ac-c1a8-4275-99df-28b1e2d067c9
Irons, Gordon P.
1241ce3c-c418-47a1-958f-c830923014cb
Hornby, Duncan D.
75cfaf57-72c1-4392-a78c-89b4b1033dca

Bowes, Michael J., Hilton, John, Irons, Gordon P. and Hornby, Duncan D. (2005) The relative contribution of sewage and diffuse phosphorus sources in the River Avon catchment, southern England: Implications for nutrient management. Science of the Total Environment, 344 (1-3 SPEC. ISS.), 67-81. (doi:10.1016/j.scitotenv.2005.02.006).

Record type: Article

Abstract

In order to effectively manage nutrient river load reductions and target remediation strategies, it is important to determine the relative contributions of diffuse and point sources across the river catchment. This study used a geographical information system (GIS) to apply phosphorus (P) export coefficients (obtained from the literature) to 58 water quality monitoring sites across a large, urbanised, mixed land use catchment, typical of southern lowland England (the River Avon, Warwickshire, UK). These coefficients were used to estimate the annual P load at each monitoring site, and also the relative contribution of point source (from sewage treatment works (STW)) and diffuse input (from both livestock and agricultural land use). The estimated annual P loads showed very close agreement (r2=0.98) with the measured total phosphorus (TP) loads. Sites with the highest proportion of P derived from STW had the highest TP concentrations and loads, and also had greater variations between seasons, with elevated P concentrations occurring during the summer months. The GIS model was re-run to determine the effect of an 80% reduction in P output from STW serving over 10 000 people, thereby assessing the effect of implementing the European Union's Urban Waste Water Treatment Directive (UWWTD). The exported TP load was reduced by 52%, but the sites with the highest TP concentrations were still those with the highest proportion of P derived from STW. The GIS model was re-run to estimate the impact of 80% P reductions at a further 11 STW of varying sizes. This reduced the total TP load by only 29 tonnes year-1, but greatly reduced the P concentrations in many highly nutrient contaminated tributaries. The number of sites with P concentrations greater than 1 mg l-1 was cut from 15 (before UWWTD implementation) to 2. These findings suggest that after UWWTD implementation, resources should focus on introducing tertiary sewage treatment at the remaining large STW, before targeting diffuse inputs. This conclusion is also likely to apply to other lowland river catchments in southern England, most of which have similar population densities to the River Avon.

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More information

e-pub ahead of print date: 17 March 2005
Published date: 15 May 2005
Keywords: Export coefficients, GIS, Nitrogen, Nutrient reduction, Phosphorus, Urban Waste Water Treatment Directive

Identifiers

Local EPrints ID: 433386
URI: http://eprints.soton.ac.uk/id/eprint/433386
ISSN: 0048-9697
PURE UUID: 645418ac-75ae-4799-87ec-e5c7574ea2c9
ORCID for Duncan D. Hornby: ORCID iD orcid.org/0000-0001-6295-1360

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Date deposited: 15 Aug 2019 16:30
Last modified: 12 Nov 2019 01:48

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Contributors

Author: Michael J. Bowes
Author: John Hilton
Author: Gordon P. Irons

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