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

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)97-105
Number of pages9
JournalWater, Air, and Soil Pollution: Focus
Issue number6
Publication statusPublished - Dec 2004
Externally publishedYes


  • Hillslope hydrology
  • Immobilisation
  • Nitrate leaching zones
  • Nitrogen saturation

ASJC Scopus subject areas

  • Water Science and Technology
  • Pollution
  • Earth-Surface Processes
  • General Earth and Planetary Sciences


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