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11 - Nitrogen flows and fate in rural landscapes
- from Part III - Nitrogen flows and fate at multiple spatial scales
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- By Pierre Cellier, INRA, France, Patrick Durand, INRA, France, Nick Hutchings, University of Aarhus, Ulli Dragosits, Centre for Ecology and Hydrology, Mark Theobald, Technical University of Madrid/Centre for Ecology and Hydrology, Jean-Louis Drouet, INRA, France, Oene Oenema, Wageningen University and Research Centre, Albert Bleeker, Energy Research Centre of the Netherlands, Lutz Breuer, Institute for Landscape Ecology and Resources Management, Tommy Dalgaard, Aarhus University, Sylvia Duretz, INRA, France, Johannes Kros, Alterra, Wageningen University and Research Centre, Benjamin Loubet, UMR Environm & Grandes Cultures, Joergen Eivind Olesen, Aarhus University Department of Agroecology and Environment, Philippe Mérot, INRA, France, Valérie Viaud, INRA, France, Wim de Vries, Wageningen University and Research Centre, Mark A. Sutton, Centre for Ecology and Hydrology
- Edited by Mark A. Sutton, NERC Centre for Ecology and Hydrology, UK, Clare M. Howard, NERC Centre for Ecology and Hydrology, UK, Jan Willem Erisman, Gilles Billen, Albert Bleeker, Peringe Grennfelt, Hans van Grinsven, Bruna Grizzetti
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- Book:
- The European Nitrogen Assessment
- Published online:
- 16 May 2011
- Print publication:
- 14 April 2011, pp 229-248
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Summary
Executive summary
Nature of the problem
The transfer of nitrogen by either farm management activities or natural processes (through the atmosphere and the hydrological network) can feed into the N cascade and lead to indirect and unexpected reactive nitrogen emissions.
This transfer can lead to large N deposition rates and impacts to sensitive ecosystems. It can also promote further N2O emission in areas where conditions are more favourable for denitrification.
In rural landscapes, the relevant scale is the scale where N is managed by farm activities and where environmental measures are applied.
Approaches
Mitigating nitrogen at landscape scale requires consideration of the interactions between natural and anthropogenic (i.e. farm management) processes.
Owing to the complex nature and spatial extent of rural landscapes, experimental assessments of reactive N flows at this scale are difficult and often incomplete. It should include measurement of N flows in the different compartments of the environment and comprehensive datasets on the environment (soils, hydrology, land use, etc.) and on farm management.
Modelling is the preferred tool to investigate the complex relationships between anthropogenic and natural processes at landscape scale although verification by measurements is required. Up to now, no model includes all the components of landscape scale N flows: farm functioning, short range atmospheric transfer, hydrology and ecosystem modelling.
7 - Nitrogen processes in aquatic ecosystems
- from Part II - Nitrogen processing in the biosphere
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- By Patrick Durand, INRA, France, Lutz Breuer, Institute for Landscape Ecology and Resources Management, Penny J. Johnes, University of Reading, Gilles Billen, University Pierre & Marie Curie, Andrea Butturini, University of Barcelona, Gilles Pinay, University of Birmingham, Hans van Grinsven, Netherlands Environmental Assessment Agency, Josette Garnier, UMR Sisyphe UPMC ' CNRS, Michael Rivett, University of Birmingham, David S. Reay, University of Edinburgh, Chris Curtis, University College London Environmental Change Research Centre, Jan Siemens, University of Bonn Institute of Crop Science and Resource Conservation – Soil Sciences, Stephen Maberly, Centre for Ecology and Hydrology, Øyvind Kaste, Norwegian Institute for Water Research, Christoph Humborg, Stockholm University, Roos Loeb, B-ware Research Centre, Jeroen de Klein, Wageningen University and Research Centre, Josef Hejzlar, Institute of Hydrobiology, Nikos Skoulikidis, Pirkko Kortelainen, Finnish Environment Institute, Ahti Lepistö, Finnish Environment Institute, Richard Wright, Norwegian Institute for Water Research
- Edited by Mark A. Sutton, NERC Centre for Ecology and Hydrology, UK, Clare M. Howard, NERC Centre for Ecology and Hydrology, UK, Jan Willem Erisman, Gilles Billen, Albert Bleeker, Peringe Grennfelt, Hans van Grinsven, Bruna Grizzetti
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- Book:
- The European Nitrogen Assessment
- Published online:
- 16 May 2011
- Print publication:
- 14 April 2011, pp 126-146
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- Chapter
- Export citation
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Summary
Executive summary
Nature of the problem
Freshwater ecosystems play a key role in the European nitrogen (N) cycle, both as a reactive agent that transfers, stores and processes N loadings from the atmosphere and terrestrial ecosystems, and as a natural environment severely impacted by the increase of these loadings.
Approaches
This chapter is a review of major processes and factors controlling N transport and transformations for running waters, standing waters, groundwaters and riparian wetlands.
Key findings/state of knowledge
The major factor controlling N processes in freshwater ecosystems is the residence time of water, which varies widely both in space and in time, and which is sensitive to changes in climate, land use and management.
The effects of increased N loadings to European freshwaters include acidification in semi-natural environments, and eutrophication in more disturbed ecosystems, with associated loss of biodiversity in both cases.
An important part of the nitrogen transferred by surface waters is in the form of organic N, as dissolved organic N (DON) and particulate organic N (PON). This part is dominant in semi-natural catchments throughout Europe and remains a significant component of the total N load even in nitrate enriched rivers.
In eutrophicated standing freshwaters N can be a factor limiting or co-limiting biological production, and control of both N and phosphorus (P) loading is often needed in impacted areas, if ecological quality is to be restored.
Solute behaviour and export rates in neotropical montane catchments under different land-uses
- Amelie Bücker, Patricio Crespo, Hans-Georg Frede, Lutz Breuer
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- Journal:
- Journal of Tropical Ecology / Volume 27 / Issue 3 / May 2011
- Published online by Cambridge University Press:
- 10 March 2011, pp. 305-317
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To improve our knowledge of the influence of land-use on solute behaviour and export rates in neotropical montane catchments we investigated total organic carbon (TOC), Ca, Mg, Na, K, NO3 and SO4 concentrations during April 2007–May 2008 at different flow conditions and over time in six forested and pasture-dominated headwaters (0.7–76 km2) in Ecuador. NO3 and SO4 concentrations decreased during the study period, with a continual decrease in NO3 and an abrupt decrease in February 2008 for SO4. We attribute this to changing weather regimes connected to a weakening La Niña event. Stream Na concentration decreased in all catchments, and Mg and Ca concentration decreased in all but the forested catchments during storm flow. Under all land-uses TOC increased at high flows. The differences in solute behaviour during storm flow might be attributed to largely shallow subsurface and surface flow paths in pasture streams on the one hand, and a predominant origin of storm flow from the organic layer in the forested streams on the other hand. Nutrient export rates in the forested streams were comparable to the values found in literature for tropical streams. They amounted to 6–8 kg ha−1 y−1 for Ca, 7–8 kg ha−1 y−1 for K, 4–5 kg ha−1 y−1 for Mg, 11–14 kg ha−1 y−1 for Na, 19–22 kg ha−1 y−1 for NO3 (i.e. 4.3–5.0 kg ha−1 y−1 NO3-N) and 17 kg ha−1 y−1 for SO4. Our data contradict the assumption that nutrient export increases with the loss of forest cover. For NO3 we observed a positive correlation of export value and percentage forest cover.