Catchment land use effects on fluxes and concentrations of organic and inorganic nitrogen in streams

Vogt, Esther; Braban, Christine F. ORCID: https://orcid.org/0000-0003-4275-0152; Dragosits, Ulrike ORCID: https://orcid.org/0000-0002-9283-6467; Durand, Patrick; Sutton, Mark A. ORCID: https://orcid.org/0000-0002-6263-6341; Theobald, Mark R.; Rees, Robert M.; McDonald, Chris; Murray, Scott; Billett, Michael F.. 2015 Catchment land use effects on fluxes and concentrations of organic and inorganic nitrogen in streams. Agriculture, Ecosystems and Environment, 199. 320-332. 10.1016/j.agee.2014.10.010

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Abstract/Summary

We present annual downstream fluxes and spatial variation in concentrations of dissolved inorganic nitrogen (NH4+ and NO3−) and dissolved organic nitrogen (DON) in two adjacent Scottish catchments with contrasting land use (agricultural grassland vs. semi-natural moorland). Inter- and intra-catchment variation in N species and the relation to spatial differences in agricultural land use were studied by determining catchment N input through agricultural activities at the field scale and atmospheric inputs at a 25 m grid resolution. The average agricultural N input of 52 kg N ha−1 yr−1 to the grassland catchment was more than 4 times higher than the input of 12 kg N ha−1 yr−1 to the moorland catchment, supplemented by 12.3 and 8.2 kg N ha−1 yr−1 through atmospheric deposition, respectively. The grassland catchment was associated with an annual downstream total dissolved nitrogen (TDN) flux of 14.4 kg N ha−1 yr−1, which was 66% higher than the flux of 8.7 kg ha−1 yr−1 from the moorland catchment. This difference was largely due to the NO3− flux being one order of magnitude higher in the grassland catchment. Dissolved organic N fluxes were similar for the two catchments (7.0 kg ha−1 yr−1) with DON contributing 49% to the TDN flux in the grassland compared with 81% in the moorland catchment. The results highlight the importance of diffuse agricultural N inputs to stream NO3− concentrations and the importance of quantifying all the major aquatic N species for developing a better understanding of N transformations and transport in the atmosphere-soil-water system.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1016/j.agee.2014.10.010
UKCEH and CEH Sections/Science Areas:	UKCEH Fellows Dise
ISSN:	0167-8809
Additional Keywords:	nitrogen, organic nitrogen, stream export, catchment flux, land use
NORA Subject Terms:	Ecology and Environment
Date made live:	23 Dec 2014 14:13 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/508727

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