A Conceptual Model of Spatially Heterogeneous Nitrogen Leaching from a Welsh Moorland Catchment |
| |
Authors: | C D Evans B Reynolds C J Curtis H D Crook D Norris and S A Brittain |
| |
Institution: | (1) Centre for Ecology and Hydrology, Orton Building, LL57 2UP Bangor, UK;(2) ECRC, University College London, 26 Bedford Way, WC1H 0AP London, UK;(3) Department of Geography, School of Human and Environmental Sciences, University of Reading, RG6 6AB Whiteknights, Reading, UK |
| |
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 (NO
3
–
), either through incomplete immobilisation in the organic layer, or in water bypassing the organic soil matrix via macropores. This NO
3
–
reaches the stream where mineral soilwaters discharge (via matrix throughflow or pipeflow) directly to the drainage network, or via small N-enriched flush wetlands. NO
3
–
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 NO
3
–
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 NO
3
–
concentrations. |
| |
Keywords: | hillslope hydrology immobilisation nitrate leaching zones nitrogen saturation |
本文献已被 SpringerLink 等数据库收录! |
|