Water, Air, & Soil Pollution: Focus

, Volume 4, Issue 6, pp 97–105

A conceptual model of spatially heterogeneous nitrogen leaching from a welsh moorland catchment

  • C. D. Evans
  • B. Reynolds
  • C. J. Curtis
  • H. D. Crook
  • D. Norris
  • S. A. Brittain
Article

DOI: 10.1007/s11267-005-3019-7

Cite this article as:
Evans, C.D., Reynolds, B., Curtis, C.J. et al. Water Air Soil Pollut: Focus (2005) 4: 97. doi:10.1007/s11267-005-3019-7
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Abstract

Soil- and stream-water data from the Plynlimon research area, mid-Wales, have been used to develop a conceptual model of spatial variations in nitrogen (N) leaching within moorland catchments. Extensive peats, in both hilltop and valley locations, are considered near-complete sinks for inorganic N, but leach the most dissolved organic nitrogen (DON). Peaty mineral soils on hillslopes also retain inorganic N within upper organic horizons, but a proportion percolates into mineral horizons as nitrate (NO3), either through incomplete immobilisation in the organic layer, or in water bypassing the organic soil matrix via macropores. This NO3 reaches the stream where mineral soilwaters discharge (via matrix throughflow or pipeflow) directly to the drainage network, or via small N-enriched flush wetlands. NO3 in hillslope waters discharging into larger valley wetlands will be removed before reaching the stream. A concept of catchment ‘nitrate leaching zones’ is proposed, whereby most stream NO3 derives from localised areas of mineral soil hillslope draining directly to the stream; the extent of these zones within a catchment may thus determine its overall susceptibility to elevated surface water NO3 concentrations.

Keywords

hillslope hydrology immobilisation nitrate leaching zones nitrogen saturation 

Copyright information

© Kluwer Academic Publishers 2004

Authors and Affiliations

  • C. D. Evans
    • 1
  • B. Reynolds
    • 1
  • C. J. Curtis
    • 2
  • H. D. Crook
    • 1
    • 3
  • D. Norris
    • 1
  • S. A. Brittain
    • 1
  1. 1.Centre for Ecology and HydrologyBangorUK
  2. 2.ECRC, University College LondonLondonUK
  3. 3.Department of Geography, School of Human and Environmental SciencesUniversity of ReadingWhiteknights, ReadingUK

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