Publication Date:
2014-11-04
Description:
The temporal variability in nitrogen (N) transport in the Corbeira agroforestry catchment (NW Spain) was analyzed from October 2004 to September 2008. Nitrate (NO 3 -N) and total Kjeldahl nitrogen (TKN) loads and concentrations were determined at various time scales (annual, seasonal and event). The results revealed a strong intra- and inter-annual variability in N transport influenced by weather patterns, and consequently by the hydrological regime. Mean annual export of total N in the catchment was 5.5 kg ha -1 yr -1 , with NO 3 -N being the dominant form. Runoff events comprised 10% of the study period, but contributed 40% and 61% of the total NO 3 -N and TKN loads, respectively. The NO 3 -N and TKN concentrations were higher during runoff events than under baseflow conditions, pointing to diffuse sources of N. The mobilization of TKN during runoff events was attributed to surface runoff, while NO 3 -N might be related to subsurface and groundwater flow. Runoff events were characterized by high variability in N loads and concentrations. Higher variability was observed in N loads than in N concentrations, indicating that event magnitude plays an important role in N transport in this catchment; event magnitude explained approximately 96% of the NO 3 -N load. However, a combination of variables related to runoff-event intensity (rainfall, discharge increase and kinetic energy) explained only 66% of the TKN load. This article is protected by copyright. All rights reserved.
Print ISSN:
0885-6087
Electronic ISSN:
1099-1085
Topics:
Architecture, Civil Engineering, Surveying
,
Geography
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