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Rapid immobilisation and leaching of wet-deposited nitrate in upland organic soils

Evans, Chris D.; Norris, Dave; Ostle, Nick; Grant, Helen; Rowe, Edwin C.; Curtis, Chris J.; Reynolds, Brian. 2008 Rapid immobilisation and leaching of wet-deposited nitrate in upland organic soils. Environmental Pollution, 156 (3). 636-643. 10.1016/j.envpol.2008.06.019

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Abstract/Summary

Nitrate (NO3−) is often observed in surface waters draining terrestrial ecosystems that remain strongly nitrogen (N) limited. It has been suggested that this occurs due to hydrological bypassing of soil or vegetation N retention, particularly during high flows. To test this hypothesis, artificial rain events were applied to 12 replicate soil blocks on a Welsh podzolic acid grassland hillslope, labelled with 15N-enriched NO3− and a conservative bromide (Br−) tracer. On average, 31% of tracer-labelled water was recovered within 4 h, mostly as mineral horizon lateral flow, indicating rapid vertical water transfer through the organic horizon via preferential flowpaths. However, on average only 6% of 15N-labelled NO3− was recovered. Around 80% of added NO3− was thus rapidly immobilised, probably by microbial communities present on the surfaces of preferential flowpaths. Transitory exceedance of microbial N-uptake capacity during periods of high water and N flux may therefore provide a mechanism for NO3− leaching. Nitrate retention occurs rapidly in organic soils along preferential flowpaths.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1016/j.envpol.2008.06.019
Programmes: CEH Programmes pre-2009 publications > Biogeochemistry
CEH Sections: Shore
Emmett
ISSN: 0269-7491
Additional Keywords: Nitrate, Atmospheric deposition, Nitrogen saturation, 15N tracer, Immobilisation
NORA Subject Terms: Agriculture and Soil Science
Ecology and Environment
Date made live: 02 Dec 2008 10:36
URI: http://nora.nerc.ac.uk/id/eprint/4444

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