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Sci Total Environ. 2014 Aug 15;490:405-15. doi: 10.1016/j.scitotenv.2014.04.122. Epub 2014 May 24.

Evaluating the critical source area concept of phosphorus loss from soils to water-bodies in agricultural catchments.

Author information

1
Agricultural Catchments Programme, Teagasc, Wexford, Ireland; School of Environmental & Biological Sciences, University College Dublin, Dublin, Ireland. Electronic address: mairead.shore@teagasc.ie.
2
School of Environmental Sciences, University of Ulster, Coleraine, N. Ireland, United Kingdom. Electronic address: P.Jordan@ulster.ac.uk.
3
Agricultural Catchments Programme, Teagasc, Wexford, Ireland. Electronic address: per-erik.mellander@teagasc.ie.
4
School of Environmental & Biological Sciences, University College Dublin, Dublin, Ireland. Electronic address: mary.kelly-quinn@ucd.ie.
5
Environmental Research Centre, Teagasc, Wexford, Ireland. Electronic address: david.wall@teagasc.ie.
6
School of Agriculture and Food Science, University College Dublin, Dublin, Ireland. Electronic address: paul.murphy@ucd.ie.
7
National Centre for Engineering in Agriculture, University of Southern Queensland, Toowoomba, Australia. Electronic address: alice.melland@usq.edu.au.

Abstract

Using data collected from six basins located across two hydrologically contrasting agricultural catchments, this study investigated whether transport metrics alone provide better estimates of storm phosphorus (P) loss from basins than critical source area (CSA) metrics which combine source factors as well. Concentrations and loads of P in quickflow (QF) were measured at basin outlets during four storm events and were compared with dynamic (QF magnitude) and static (extent of highly-connected, poorly-drained soils) transport metrics and a CSA metric (extent of highly-connected, poorly-drained soils with excess plant-available P). Pairwise comparisons between basins with similar CSA risks but contrasting QF magnitudes showed that QF flow-weighted mean TRP (total molybdate-reactive P) concentrations and loads were frequently (at least 11 of 14 comparisons) more than 40% higher in basins with the highest QF magnitudes. Furthermore, static transport metrics reliably discerned relative QF magnitudes between these basins. However, particulate P (PP) concentrations were often (6 of 14 comparisons) higher in basins with the lowest QF magnitudes, most likely due to soil-management activities (e.g. ploughing), in these predominantly arable basins at these times. Pairwise comparisons between basins with contrasting CSA risks and similar QF magnitudes showed that TRP and PP concentrations and loads did not reflect trends in CSA risk or QF magnitude. Static transport metrics did not discern relative QF magnitudes between these basins. In basins with contrasting transport risks, storm TRP concentrations and loads were well differentiated by dynamic or static transport metrics alone, regardless of differences in soil P. In basins with similar transport risks, dynamic transport metrics and P source information additional to soil P may be required to predict relative storm TRP concentrations and loads. Regardless of differences in transport risk, information on land use and management, may be required to predict relative differences in storm PP concentrations between these agricultural basins.

KEYWORDS:

Basin; Critical source area; Hydrology; Quickflow; Soil; Transport risk

PMID:
24863139
DOI:
10.1016/j.scitotenv.2014.04.122
[Indexed for MEDLINE]
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