The European Nitrogen Assessmentassets.cambridge.org/97811070/06126/frontmatter/9781107006126... ·...

The European Nitrogen AssessmentSources, Effects and Policy Perspectives

A century ago, when the world depended on fossil nitrogen and manure recycling, there was insufficient reactive nitrogen to feed the growing human population. With the invention of the Haber–Bosch process, humans found a way to make cheap reactive nitrogen from the almost inexhaustable supply of atmospheric di-nitrogen. What humans did not anticipate was that the massive increase in reactive nitrogen supply, exacerbated by fossil fuel burning, would lead to a web of new environmental problems cutting across all global-change challenges.

The European Nitrogen Assessment presents the first full, continental-scale assessment of reactive nitrogen in the environment and sets the problem in context by providing a multidisciplinary introduction to the key processes in the nitrogen cycle. Issues of up-scaling from field, farm and city to national and continental scales are addressed in detail with emphasis on opportunities for better management at local to global levels. A comprehensive series of maps showing nitrogen pools and fluxes across Europe also highlight the location of the major threats and allow a comparison of national budgets for the first time. Five key societal threats posed by reactive nitrogen are assessed, providing a framework for a set of policies that can be used for joined-up management of the nitrogen cycle in Europe. This includes the first cost–benefit analysis for different reactive nitrogen forms and consideration of future scenarios.

Incorporating a handy technical synopsis and summary for policy makers, this land-mark volume is an essential reference for academic researchers across a wide range of disciplines, as well as for stakeholders and policy makers in Europe and beyond. It is also a valuable tool in helping communicate the key environmental issues and future challenges to the wider public.

Mark Sutton is an environmental physicist investigating human alteration of the nitrogen cycle, with specific attention to ammonia. He is coordinator of the major integrated project ‘NitroEurope’, a 5-year effort, bringing together 64 research institutes to ask how nitrogen is affecting the European greenhouse gas balance. Dr Sutton is vice-chair of the ‘Nitrogen in Europe’ (NinE) programme of the European Science Foundation, the Director of the European Centre of the International Nitrogen Initiative (INI) and co-chair of the Task Force on Reactive Nitrogen of the UN-ECE Convention on Long-range Transboundary Air Pollution.

Clare Howard is currently engaged in a postdoctoral fellowship in knowledge transfer, with an emphasis on research networks which focus on nitrogen. Dr Howard is project coordinator for the European Nitrogen Assessment and for the Task Force on Reactive Nitrogen, which sits beneath the Working Group on Strategies and Review of the Convention on Long Range Transboundary Air Pollution. Her research interests involve the modelling of biogeochemical cycles of nitrogen and carbon and assessing uncertainty in model systems.

Jan Willem Erisman heads the Biomass, Coal and Environmental Research Unit of the Energy Research Centre of the Netherlands (ECN) and is a professor in Integrated Nitrogen studies at Vrije Universiteit, Amsterdam. His research focuses on atmosphere–biosphere exchange of gases and aerosols related to acidification and eutrophication and climate change. He was instrumental in establishing the International Nitrogen Initiative, the Nanjing Declaration on Nitrogen Management, the EU 6th Framework research program NitroEurope and for chairing the European Science Foundation project NinE and the EU COST Action 729.

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Gilles Billen is research director of the Centre National de la Recherche Scientifique (CNRS) at the University Pierre and Marie Curie (Paris) where his research covers many aspects of biogeochemistry, with an emphasis on the nitrogen, phosphorus and silica cycles. His main expertise is on the assessment and modelling of the ecological functioning of hydrosystems, including marine, estuarine and freshwater environments. From 1997 to 2007, he was the Director of the PIREN-Seine programme, a large interdisciplinary research programme on the Seine river watershed.

Albert Bleeker works as a senior scientist at the Energy Research Centre of the Netherlands, in the department of Air Quality and Climate Change. He has almost 20 years of experience in the field of nitrogen, where his main expertise is on the atmospheric emission, transport and deposition of nitrogen at various spatial scales, as well as studies on the effect of nitrogen in the natural environment. Currently, he is the Nitrogen in Europe (NinE) Programme Co-ordinator and a member of the COST 729 Management Committee.

Peringe Grennfelt has a background in atmospheric chemistry. His research includes regional air pollution problems in Europe, in particular acidification, nitrogen deposition and tropospheric ozone. He has coordinated several national and international research programmes including the EU project Network for the support of European Policies on Air Pollution (NEPAP). He is presently leading the Mistra Climate Policy Research Programme (Clipore) and the Swedish Clean Air Research Programme (SCARP).

Hans van Grinsven works at the Netherlands Environmental Assessment Agency where he conducts research and coordinates projects related to agriculture and environment, focusing on nitrogen and phosphorus, and sustainable food production. Dr van Grinsven was responsible for evaluations of national implementation of the EU Nitrates Directive and was also closely involved in the evaluations of the implementation of the EU Water framework Directive and EU NEC directive.

Bruna Grizzetti is a researcher in the field of large scale modelling of nutrient and water transfer. She works on modelling nutrient pressures on water at European scale in support to the implementation of environmental European policies, such as the Water Framework Directive, Nitrates Directive and the Marine Strategy. Since 2007, Dr Grizzetti has been a member of the Coordination Team of the European Nitrogen Assessment process, supported through the European Science Foundation.






TFRN

The European Nitrogen Assessment has been prepared through coordinated action led by the Nitrogen in Europe (NinE) Research Networking Programme of the European Science Foundation, the NitroEurope Integrated Project supported by European Commission’s 6th Framework Programme and the COST Action 729. The Assessment is a con-tribution to the work of the Task Force on Reactive Nitrogen (TFRN), led by the UK and the Netherlands, in support of the long-term goals of the UN-ECE Convention on Long-range Transboundary Air Pollution (CLRTAP). In parallel, the Assessment represents a European contribution to the work of the International Nitrogen Initiative (INI), a joint project of the International Geosphere Biosphere Programme (IGBP) and the Scientific Committee on Problems of the Environment (SCOPE), providing evidence to underpin many United Nations and other multi-lateral agreements. The actual assessment work has been carried out by 200 experts from 21 countries and 89 organizations which kindly provided support for this work.

The ENA has been conducted as a scientifically independent process. The views and conclusions expressed are those of the authors, and do not necessarily reflect policies of the contributing organizations.






Acknowledgements

The European Nitrogen Assessment was prepared by the list of contributors given on page ix, with the support of the NinE Programme of the European Science Foundation, the NitroEurope IP (funded by the European Commission 6th Framework Programme), the COST Action 729, the Task Force on Reactive Nitrogen and the International Nitrogen Initiative. The editors gratefully acknowledge the wider sup-port which the assessment received, in the form of all those attending and hosting the ENA workshops, internal and

external reviewers of chapters and summaries. We particu-larly thank Agnieszka Eljasz of CEH, Susan Francis and Laura Clark of Cambridge University Press, Ellen Degott-v.W.Rekowski and Paola Campus of the European Science Foundation, Peter Coleman of Defra, Anastasios Kentarchos of the European Commission, Matti Johannsson and Tea Aulavuo of the Secretariat to the UN-ECE Convention on Long-range Transboundary Air Pollution for their support through this process.






The European Nitrogen AssessmentSources, Effects and Policy PerspectivesEdited by

Mark A. SuttonNERC Centre for Ecology and Hydrology

Clare M. HowardNERC Centre for Ecology and Hydrology and University of Edinburgh

Jan Willem ErismanEnergy Research Centre of the Netherlands

Gilles BillenCNRS and University of Paris VI

Albert BleekerEnergy Research Centre of the Netherlands

Peringe GrennfeltSwedish Environmental Research Institute (IVL)

Hans van GrinsvenPBL Netherlands Environmental Assessment Agency

Bruna GrizzettiEuropean Commission Joint Research Centre






CAMBRID GE UNIVERSIT Y PRESSCambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo, Delhi, Tokyo, Mexico City

Cambridge University PressThe Edinburgh Building, Cambridge CB2 8RU, UK

Published in the United States of America by Cambridge University Press, New York

www.cambridge.orgInformation on this title: www.cambridge.org/9781107006126

© Cambridge University Press 2011© Editorial contributions by Bruna Grizzetti, European Union 2011© Chapter 17, European Union 2011

This publication is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press.

First published 2011

Printed in the United Kingdom at the University Press, Cambridge

A catalogue record for this publication is available from the British Library

Library of Congress Cataloguing in Publication DataThe European nitrogen assessment : sources, effects, and policy

perspectives / [edited by] Mark A. Sutton ... [et al.]. p. cm.

Includes bibliographical references and index.ISBN 978-1-107-00612-6 (hardback)1. Nitrogen compounds–Environmental aspects–Europe.2. Nitrogen cycle–Europe. 3. Nitrogen fertilizers–Government policy–Europe. I. Sutton, Mark A. TD196.N55E96 2011363.738–dc22 2010051120

ISBN 978-1-107-00612-6 Hardback

Additional resources for this publication at www.cambridge.org/ena

Cambridge University Press has no responsibility for the persistence or accuracy of URLs for external or third-party internet websites referred to in this publication, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate.






vii

Contents

List of contributors page xiForeword xxiiiSummary for policy makers xxivTechnical summary xxxv

1 Assessing our nitrogen inheritance 1Mark A. Sutton, Clare M. Howard, Jan Willem Erisman, Gilles Billen, Albert Bleeker, Peringe Grennfelt, Hans van Grinsven and Bruna Grizzetti

Part I Nitrogen in Europe: the present position2 The European nitrogen problem in a global

perspective 9Jan Willem Erisman, Hans van Grinsven, Bruna Grizzetti, Fayçal Bouraoui, David Powlson, Mark A. Sutton, Albert Bleeker and Stefan Reis

3 Benefits of nitrogen for food, fibre and industrial production 32Lars Stoumann Jensen, Jan K. Schjoerring, Klaas W. van der Hoek, Hanne Damgaard Poulsen, John F. Zevenbergen, Christian Pallière, Joachim Lammel, Frank Brentrup, Age W. Jongbloed, Jaap Willems and Hans van Grinsven

4 Nitrogen in current European policies 62Oene Oenema, Albert Bleeker, Nils Axel Braathen, Michaela Budňáková, Keith Bull, Pavel Čermák, Markus Geupel, Kevin Hicks, Robert Hoft, Natalia Kozlova, Adrian Leip, Till Spranger, Laura Valli, Gerard Velthof and Wilfried Winiwarter

5 The challenge to integrate nitrogen science and policies: the European Nitrogen Assessment approach 82Mark A. Sutton, Clare M. Howard, Jan Willem Erisman, William J. Bealey, Gilles Billen, Albert Bleeker, Alexander F. Bouwman, Peringe Grennfelt, Hans van Grinsven and Bruna Grizzetti

Part II Nitrogen processing in the biosphere6 Nitrogen processes in terrestrial ecosystems 99

Klaus Butterbach-Bahl, Per Gundersen, Per Ambus, Jürgen Augustin, Claus Beier, Pascal Boeckx, Michael

Dannenmann, Benjamin Sanchez Gimeno, Ralf Kiese, Barbara Kitzler, Andreas Ibrom, Robert M. Rees, Keith A. Smith, Carly Stevens, Timo Vesala and Sophie Zechmeister-Boltenstern

7 Nitrogen processes in aquatic ecosystems 126Patrick Durand, Lutz Breuer, Penny J. Johnes, Gilles Billen, Andrea Butturini, Gilles Pinay, Hans van Grinsven, Josette Garnier, Michael Rivett, David S. Reay, Chris Curtis, Jan Siemens, Stephen Maberly, Øyvind Kaste, Christoph Humborg, Roos Loeb, Jeroen de Klein, Josef Hejzlar, Nikos Skoulikidis, Pirkko Kortelainen, Ahti Lepistö and Richard Wright

8 Nitrogen processes in coastal and marine ecosystems 147Maren Voss, Alex Baker, Hermann W. Bange, Daniel Conley, Sarah Cornell, Barbara Deutsch, Anja Engel, Raja Ganeshram, Josette Garnier, Ana-Stiina Heiskanen, Tim Jickells, Christiane Lancelot, Abigail McQuatters-Gollop, Jack Middelburg, Doris Schiedek, Caroline P. Slomp and Daniel P. Conley

9 Nitrogen processes in the atmosphere 177Ole Hertel, Stefan Reis, Carsten Ambelas Skjøth, Albert Bleeker, Roy Harrison, John Neil Cape, David Fowler, Ute Skiba, David Simpson, Tim Jickells, Alex Baker, Markku Kulmala, Steen Gyldenkærne, Lise Lotte Sørensen and Jan Willem Erisman

Part III Nitrogen flows and fate at multiple spatial scales

10 Nitrogen flows in farming systems across Europe 211Steve Jarvis, Nick Hutchings, Frank Brentrup, Jørgen Eivind Olesen and Klaas W. van der Hoek

11 Nitrogen flows and fate in rural landscapes 229Pierre Cellier, Patrick Durand, Nick Hutchings, Ulli Dragosits, Mark Theobald, Jean-Louis Drouet,






Contents

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Oene Oenema, Albert Bleeker, Lutz Breuer, Tommy Dalgaard, Sylvia Duretz, Johannes Kros, Benjamin Loubet, Joergen Eivind Olesen, Philippe Mérot, Valérie Viaud, Wim de Vries and Mark A. Sutton

12 Nitrogen flows and fate in urban landscapes 249Anastasia Svirejeva-Hopkins, Stefan Reis, Jakob Magid, Gabriela B. Nardoto, Sabine Barles, Alexander F. Bouwman, Ipek Erzi, Marina Kousoulidou, Clare M. Howard and Mark A. Sutton

13 Nitrogen flows from European regional watersheds to coastal marine waters 271Gilles Billen, Marie Silvestre, Bruna Grizzetti, Adrian Leip, Josette Garnier, Maren Voss, Robert Howarth, Fayçal Bouraoui, Ahti Lepistö, Pirkko Kortelainen, Penny Johnes, Chris Curtis, Christoph Humborg, Erik Smedberg, Øyvind Kaste, Raja Ganeshram, Arthur Beusen and Christiane Lancelot

14 Atmospheric transport and deposition of reactive nitrogen in Europe 298David Simpson, Wenche Aas, Jerzy Bartnicki, Haldis Berge, Albert Bleeker, Kees Cuvelier, Frank Dentener, Tony Dore, Jan Willem Erisman, Hilde Fagerli, Chris Flechard, Ole Hertel, Hans van Jaarsveld, Mike Jenkin, Martijn Schaap, Valiyaveetil Shamsudheen Semeena, Philippe Thunis, Robert Vautard and Massimo Vieno

15 Geographical variation in terrestrial nitrogen budgets across Europe 317Wim de Vries, Adrian Leip, Gert Jan Reinds, Johannes Kros, Jan Peter Lesschen, Alexander F. Bouwman, Bruna Grizzetti, Fayçal Bouraoui, Klaus Butterbach-Bahl, Peter Bergamaschi and Wilfried Winiwarter

16 Integrating nitrogen fluxes at the European scale 345Adrian Leip, Beat Achermann, Gilles Billen, Albert Bleeker, Alexander F. Bouwman, Wim de Vries, Ulli Dragosits, Ulrike Döring, Dave Fernall, Markus Geupel, Jürg Herolstab, Penny Johnes, Anne-Christine Le Gall, Suvi Monni, Rostislav Nevečeřal, Lorenzo Orlandini, Michel Prud’homme, Hannes I. Reuter, David Simpson, Günther Seufert, Till Spranger, Mark A. Sutton, John van Aardenne, Maren Voß and Wilfried Winiwarter

Part IV Managing nitrogen in relation to key societal threats

17 Nitrogen as a threat to European water quality 379Bruna Grizzetti, Fayçal Bouraoui, Gilles Billen, Hans van Grinsven, Ana Cristina Cardoso, Vincent Thieu, Josette Garnier, Chris Curtis, Robert Howarth and Penny Johnes

18 Nitrogen as a threat to European air quality 405Jana Moldanová, Peringe Grennfelt, Åsa Jonsson, David Simpson, Till Spranger, Wenche Aas, John Munthe and Ari Rabl

19 Nitrogen as a threat to the European greenhouse balance 434Klaus Butterbach-Bahl, Eiko Nemitz, Sönke Zaehle, Gilles Billen, Pascal Boeckx, Jan Willem Erisman, Josette Garnier, Rob Upstill-Goddard, Michael Kreuzer, Oene Oenema, Stefan Reis, Martijn Schaap, David Simpson, Wim de Vries, Wilfried Winiwarter and Mark A. Sutton

20 Nitrogen as a threat to European terrestrial biodiversity 463Nancy B. Dise, Michael Ashmore, Salim Belyazid, Albert Bleeker, Roland Bobbink, Wim de Vries, Jan Willem Erisman, Till Spranger, Carly J. Stevens and Leon van den Berg

21 Nitrogen as a threat to European soil quality 495Gerard Velthof, Sébastien Barot, Jaap Bloem, Klaus Butterbach-Bahl, Wim de Vries, Johannes Kros, Patrick Lavelle, Jørgen Eivind Olesen and Oene Oenema

Part V European nitrogen policies and future challenges

22 Costs and benefits of nitrogen in the environment 513Corjan Brink, Hans van Grinsven, Brian H. Jacobsen, Ari Rabl, Ing-Marie Gren, Mike Holland, Zbigniew Klimont, Kevin Hicks, Roy Brouwer, Roald Dickens, Jaap Willems, Mette Termansen, Gerard Velthof, Rob Alkemade, Mark van Oorschot and Jim Webb

23 Developing integrated approaches to nitrogen management 541Oene Oenema, Joost Salomez, Christina Branquinho, Michaela Budňáková, Pavel Čermák, Markus Geupel, Penny Johnes, Chris Tompkins, Till Spranger, Jan Willem Erisman, Christian Pallière, Luc Maene, Rocio Alonso, Rob Maas, Jacob Magid, Mark A. Sutton and Hans van Grinsven

24 Future scenarios of nitrogen in Europe 551Wilfried Winiwarter, Jean-Paul Hettelingh, Alex F. Bouwman, Wim de Vries, Jan Willem Erisman, James Galloway, Zbigniew Klimont, Allison Leach, Adrian Leip, Christian Pallière, Uwe A. Schneider, Till Spranger, Mark A. Sutton, Anastasia Svirejeva-Hopkins, Klaas W. van der Hoek and Peter Witzke






Contents

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25 Coordinating European nitrogen policies between international conventions and intergovernmental organizations 570Keith Bull, Robert Hoft and Mark A. Sutton

26 Societal choice and communicating the European nitrogen challenge 585David S. Reay, Clare M. Howard, Albert Bleeker, Pete Higgins, Keith Smith, Henk Westhoek, Trudy Rood,

Mark R. Theobald, Alberto Sanz-Cobeña, Robert M. Rees, Dominic Moran, Kate Ravilious and Stefan Reis

Glossary 602Index 607






xi

John van AardenneEuropean Commission Joint Research CenterInstitute for Environment and Sustainabilityvia Enrico Fermi 274921027 Ispra (VA)Italy

Wenche AasNILU, Norwegian Institute for Air ResearchPB 1002027 KjellerNorway

Beat AchermannFederal Office for the EnvironmentAir Pollution Control and NIR DivisionAir Quality Management SectionCH-3003 BernSwitzerland

Rob AlkemadeNetherlands Environmental Assessment AgencyP.O. Box 3033720 AHThe Netherlands

Per AmbusRisø DTU National Laboratory for Sustainable Energy, Technical University of DenmarkBiosystems DivisionFrederiksborgvej 3994000 RoskildeDenmark

Michael AshmoreUniversity of YorkEnvironment DepartmentHeslingonYO10 5DDUnited Kingdom

Juergen AugustinLeibniz-Centre for Agricultural Landscape Research (ZALF)Eberswalder Strasse 84Muencheberg

D-15374Germany

Alex BakerSchool of Environmental SciencesUniversity of East AngliaNorwichNR4 7TJUnited Kingdom

Hermann W. BangeIFM-GEOMAR, Leibniz-Institut für MeereswissenschaftenDüsternbrooker Weg 20KielD-24226Germany

Sabine BarlesUniversité Paris Est – LATTS,Institut Français d’Urbanisme4 rue Alfred Nobel – Cité DescartesChamps-sur-Marne77420France

Sébastien BarotIRD-Bioemco,Bioemco ENS46 rue d’Ulm75230 Paris Cedex 05France

Jerzy BartnickiNorwegian Meteorological InstituteP.O. Box 43OsloNO-0313Norway

Claus BeierRisØ DTU, National Laboratory for Sustainable EnergyEcosystems Research ProgrammeP.O. Box 3584000 RoskildeDenmark

Contributors






List of Contributors

xii

Salim Belyazid Belyazid Consulting and Communication AB, Österportsgatan 5a 21128 Malmö Sweden

Leon J. L. van den Berg Radboud University Nijmegen Heyendaalseweg 135 6525 AJ Nijmegen Th e Netherlands

Peter Bergamaschi European Commission Joint Research Centre Institute for Environment via Enrico Fermi 2749 and Sustainability 21027 290 Ispra (VA) Italy

Haldis Berge Norwegian Meteorological Institute PO 43 Blindern 0313 Oslo Norway

Arthur Beusen Netherlands Environmental Assessment Agency P.O. Box 303 3720 AH Bilthoven Th e Netherlands

Gilles Billen University Pierre & Marie Curie 4 place Jussieu 75005 Paris France

Albert Bleeker Energy Research Centre of the Netherlands P.O. Box 1 1755 ZG Petten Th e Netherlands

Jaap Bloem Alterra Wageningen University and Research Centre Soil Science Centre P.O. Box 47 6700 Wageningen Th e Netherlands

Roland Bobbink B-Ware Research Centre Radboud University P.O. Box 9010 9500 GL Nijmegen Th e Netherlands

Pascal Boeckx Ghent University Faculty of Bioscience Engineering

Coupure 653 9000 Gent Belgium

Fayçal Bouraoui European Commission Joint Research Centre via Enrico Fermi 2749 21027 Ispra (VA) Italy

Lex Bouwman Netherlands Environmental Assessment Agency P.O. Box 303 3720 AH Bilthoven Th e Netherlands

Nils-Axel Braathen OECD 2 rue André-Pascal F-75775 Paris Cedex 16 France

Cristina Branquinho Universidade de Lisboa, Faculdade de Ciências Centro de Biologia Ambiental, Campo Grande, Bloco C2, 5º Piso, sala 37 1749–016 Lisboa Portugal

Frank Brentrup Yara International, Centre for Plant Nutrition and Environmental Research Hanninghof 35 48249 Duelmen Germany

Lutz Breuer Institute for Landscape Ecology and Resources Management Research Centre for BioSystems, Land Use and Nutrition Heinrich-Buff -Ring 26 35392 Giessen Germany

Corjan Brink Netherlands Environmental Assessment Agency P.O. Box 303 3720 AH Bilthoven Th e Netherlands

Roy Brouwer VU University Amsterdam Institute for Environmental Studies De Boelelaan 1085 1081 HV Amsterdam Netherlands

Michaela Budňáková Ministry of Agriculture of the Czech Republic Těšnov 17 117 05 Praha 1 Czech Republic







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Keith R. Bull Centre for Ecology and Hydrology Lancaster Environment Centre Library Avenue Lancaster LA1 4AP United Kingdom

Klaus Butterbach-Bahl Karlsruhe Institute of TechnologyInstitute for Meterology and Climate Research Atmospheric Environmental Research Kreuzeckbahnstrasse 19 82467 Garmisch-Partenkirchen Germany

Andrea Butturini University of Barcelona Department of Ecology Faculty of Biology avd. Diagonal 645 8028 Barcelona Spain

John Neil Cape Centre for Ecology and Hydrology Bush Estate Penicuik EH26 0QB United Kingdom

Ana C. Cardoso European Commission Joint Research CentreInstitute for Environment and Sustainability via Enrico Fermi 2749 21027 Ispra (VA) Italy

Pierre Cellier INRA, UMR EGC 78850 Th iverval-Grignon France

Pavel Čermák Central Institute for Supervising and Testing in Agriculture Hroznová Street 2 656 06 Brno Czech Republic

Daniel J. Conley Lund University Department of Earth and Ecosystem Sciences Sölvegatan 12 223 62 Lund Sweden

Sarah E. Cornell University of Bristol QUEST, School of Earth Sciences

Queens Road Bristol BS8 1RJ United Kingdom

Chris J. Curtis University College LondonEnvironmental Change Research Centre Gower Street London WC1E 6BT United Kingdom

Cornelis Cuvelier European Commission Joint Research Centre P.O. Box 410 21020 Ispra (VA) Italy

Tommy Dalgaard Aarhus UniversityDepartment of Agroecology and Environment P.O. Box 50 8830 Tjele Denmark

Michael Dannenmann University of Freiburg Institute of Forest Botany and Tree Physiology Georges Köhler Allee 53/54 79110 Freiburg Germany

Frank Dentener European Commission Joint Research Centre via Enrico Fermi 2749 21027 Ispra (VA) Italy

Barbara Deutsch Stockholm University Department of Applied Environmental Science Svanthe Arrheniusväg 8 11418 Stockholm Sweden

Roald Dickens Department for the Environment Food and Rural Aff airs 17 Smith Square London SW1P 3JR United Kingdom

Nancy B. Dise Manchester Metropolitan University Department of Environmental and Geographical Sciences John Dalton East Building, Chester Street Manchester M1 5GD United Kingdom







xiv

Ulrike M. Doering European Commission Joint Research Centre Institute for Environment and Sustainability P.O. Box 290 21020 Ispra (Va) Italy

Anthony Dore Centre for Ecology and Hydrology Bush Estate Penicuik EH26 9HF United Kingdom

Ulrike Dragosits Centre for Ecology and Hydrology Bush Estate Penicuik EH26 0QB United Kingdom

Jean-Louis Drouet INRA UMR INRA/AgroParisTech Environment and Arable Crops 78850 Th iverval-Grignon France

Patrick Durand INRA UMR 1069 SAS 35000 Rennes France

Sylvia Duretz INRA UMR EGC 78850 Th iverval-Grignon France

Anja Engel Alfred Wegener Institute for Polar and Marine Research Am Handelshafen 12 27515 Bremerhaven Germany

Jan Willem Erisman Energy Research Centre of the Netherlands P.O. Box 1 1755 ZG Petten the Netherlands

Ipek Erzi TUBITAK Marmara Research Centre Environment Institute P.O. Box 21 41470 Gebze Kocaeli Turkey

Hilde Fagerli Norwegian Meteorological Institute P.O. Box 43 0313 Blindern Norway

David Fernall Department for Environment, Food and Rural Aff airs Kingspool, Peasholme Green York YO1 2PX United Kingdom

Chris R. Flechard Soils, Agro-hydro systems and Spatialization 65 rue de St-Brieuc 35042 Rennes France

David Fowler Centre for Ecology and Hydrology Bush Estate Penicuik EH26 0QB United Kingdom

James Galloway University of Virginia P.O. Box 400772 Charlottesville VA 22901 United States of America

Raja S. Ganeshram University of Edinburgh School of GeoSciences Grant Institute West Mains Road Edinburgh EH16 5NW United Kingdom

Josette Garnier UMR Sisyphe UPMC & CNRS, , 4 place Jussieu 75005 Paris France

Markus Geupel Federal Environment Agency, Germany Wörlitzer Platz 1 6844 Dessau Germany

Ing-Marie Gren Swedish University of Agricultural Sciences Department of Economics 750 07 Uppsala Sweden







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Peringe GrennfeltIVL Swedish Environmental Research Institute LtdAschebergsgatan 44P.O. Box 5302400 14 GothenburgSweden

Hans van GrinsvenNetherlands Environmental Assessment AgencyP.O. Box 303 3720 AH BilthovenThe Netherlands

Bruna GrizzettiEuropean Commission Joint Research Centrevia Enrico Fermi 274921027 Ispra (VA)Italy

Per GundersenUniversity of CopenhagenForest and Landscape DenmarkRolighedsvej 231958 FrederiksbergDenmark

Steen GyldenkærneAfdeling for SystemanalyseDanmarks MiljøundersøgelserFrederiksborgvej 3994000 RoskildeDenmark

Roy M. HarrisonUniversity of BirminghamSchool of Geography, Earth and Environmental Sci.EdgbastonBirminghamB15 2TTUnited Kingdom

Anna-Stiina HeiskanenFinnish Environment InstituteP.O. Box 140 251 HelsinkiFinland

Josef HejzlarInstitute of HydrobiologyBiology Centre AS CRNa Sadkach 7370 05 Ceske BudejoviceCzech Republic

Ole HertelUniversity of AarhusNational Environmental Research InstituteP.O. Box 3584000 RoskildeDenmark

Jean-Paul HettelinghNational Institute for Public Health and the EnvironmentCoordination Centre for EffectsP.O. Box 13720 BA BilthovenThe Netherlands

Kevin HicksUniversity of YorkStockholm Environment InstituteGrimston HouseHeslingtonYO10 5DDUnited Kingdom

Peter HigginsUniversity of EdinburghHolyrood RoadEdinburghEH8 8AQUnited Kingdom

Klaas W. van Der HoekNational Institute for Public Health and the EnvironmentP.O. Box 13720 BA BilthovenThe Netherlands

Robert HoftConvention on Biological Diversity413, Saint Jacques Street, suite 800MontrealQC H2Y 1N9Canada

Mike HollandUniversity of ReadingEMRCWhitchurch HillReadingRG8 7PWUnited Kingdom

Clare M. HowardCentre for Ecology and HydrologyBush EstatePenicuikEH23 4RBUnited Kingdom

Robert W. HowarthCornell UniversityDepartment of Ecology and Evolutionary BiologyCorson HallIthacaNY 14853United States of America

Christoph HumborgStockholm University







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Department of Applied Environmental Science Svanthe Arrheniusväg 8 10691 Stockholm Sweden

Nicholas J. Hutchings University of Aarhus Research Centre Foulum 8830 Tjele Denmark

Andreas Ibrom Risø National Laboratory for Sustainable Energy Frederiksborgvej 399 4000 Roskilde Denmark

Hans van Jaarsveld Netherlands Environmental Assessment Agency P.O. Box 303 3720 AH Bilthoven Th e Netherlands

Brian H. Jacobsen University of Copenhagen Institute of Food and Resource Economics Rolighedsvej 25 1958 Frederiksberg Denmark

Steve Jarvis Th e European Journal of Soil Science Centre for Rural Policy Research University of Exeter Amory Building, Rennes Drive Exeter EX4 4RJ United Kingdom

Michael E. Jenkin Atmospheric Chemistry Services Okehampton EX20 1FB United Kingdom

Lars Stoumann Jensen University of Copenhagen Faculty of Life Sciences Department of Agriculture and Ecology Th orvaldsensvej 40 1871 Frederiksberg C Denmark

Timothy Jickells University of East Anglia School of Environmental Sciences Norwich NR4 7TJ United Kingdom

Penny Johnes University of Reading Aquatic Environments Research Centre Whiteknights Reading RG6 6DW United Kingdom

Age W. Jongbloed Wageningen UR Livestock Research Edelhertweg 15 8219 PH Lelystad Th e Netherlands

Åsa Jonsson IVL Swedish Environmental Research Institute P.O. Box 5302 400 14 Göteborg Sweden

Øyvind Kaste Norwegian Institute for Water Research Jon Lilletuns vei 3 4879 Grimstad Norway

Ralf Kiese Karlsruhe Institute for TechnologyInstitute for meteorology and Climate ResearchAtmospheric Environmental Research Kreuzeckbahnstrasse 19 82467 Garmisch-Partenkirchen Germany

Barbara Kitzler Federal Research and Training Centre for Forests, Natural Hazardo and Landscape Seckendorff -Gudent-Weg 8 1130 Vienna Austria

Jeroen de Klein Wageningen University and Research Centre Aquatic Ecology and Water Quality Management Group P.O. Box 47 6700 AA Wageningen Th e Netherlands

Zbigniew Klimont International Institute for Applied Systems Analysis Schlossplatz 1 2361 Laxenburg Austria

Pirkko Kortelainen Finnish Environment Institute (SYKE) P.O. Box 140 00251 Helsinki Finland







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Marina KousoulidouAristotle University of ThessalonikiDepartment of Mechanical EngineeringLaboratory of Applied Thermodynamics54124 ThessalonikiGreece

Natalia KozlovaNorth-West Research Institute of Agricultural Engineering and Electrification (SZNIIMESH)P.O.Tiarlevo, Filtrovskoje shosse, 3196625 Saint-Petersburg-PavlovskRussian Federation

Michael KreuzerETH ZurichInstitute of Plant, Animal and Agroecosystem ScienceUniversitätstrasse 28092 ZurichSwitzerland

Johannes KrosAlterra, Wageningen University and Research CentreP.O. Box 476700 AA WageningenThe Netherlands

Markku KulmalaUniversity of HelsinkiDepartment of PhysicsP.O. Box 6414 HelsinkiFinland

Joachim LammelYara InternationalCentre for Plant Nutrition and Environmental ResearchHanninghof 3548249 DuelmenGermany

Christiane LancelotUniversité Libre de BruxellesEcologie des Systèmes Aquatiques ESA, CP 221Boulevard du Triomphe1050 BruxellesBelgium

Patrick LavelleCIATKm 17, Recta Cali-PalmiraApartado Aéreo6713 CaliColombia

Anne-Christine Le GallINERISEconomics and Decision for the Environment, Chronic Risks DivisionParc Technologique Alata, BP260550 Verneuil en HalatteFrance

Allison LeachUniversity of VirginiaP.O. Box 400123CharlottesvilleVA 22904United States of America

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Addressing the grand challenges of society depends funda-mentally on firm scientific evidence. Today, Europe faces sev-eral of these challenges, as outlined in the Europe 2020 strategy adopted by the Commission on 3 March 2010, including cli-mate change, energy and food security, health and an ageing population. Research and innovation are crucial to address these challenges effectively. For that reason, the Commission launched the ‘Innovation Union’ flagship initiative, with the aim to re-focus research and development as well as innovation policy on these grand societal challenges.

In this framework we very much welcome the European Nitrogen Assessment. It is fair to say that nitrogen will be a new story for many people. Yet we can here clearly identify a case of science at its best: innovative thinking that enables the development of connections from evidence-based policies to evidence-tested decisions.

The Assessment highlights how human production of react-ive nitrogen has literally changed the world. Since the invention of the Haber-Bosch process a century ago, humans have been able to double the world’s circulation of nitrogen compounds, resulting in nitrogen fertilizers sustaining around 3 billion peo-ple, almost half of the world population. It is therefore obvious that nitrogen is essential, not only to meeting the challenge for food security, but, with the increasing importance of biofuels, also for energy security.

Yet with this achievement, originating from European innovation a century ago, has also come an inheritance of envir-onmental effects that cuts across all global ecosystems. As the Assessment reveals, excess reactive nitrogen contributes to cli-mate change; it adversely affects water, air and soil quality, and is putting unsustainable pressure on ecosystems and biodiver-sity in Europe. Moreover, the surplus of nitrogen compounds leaking into air and water may lead to a substantial health risk for vulnerable human populations.

The Assessment highlights how nitrogen is related to each of the great challenges that European society faces, and the need to develop joined up approaches to address them. In this respect the European Nitrogen Assessment is an important step, building scientific and institutional bridges and sharing different perspectives. It is rewarding to see different environ-mental disciplines being brought together, and scientists pro-actively seeking to engage European industry, policy makers and the public.

These significant commitments also emphasize the import-ance of critical mass in the European Research Area. The Assessment is a key output from a large amount of ongoing research in Europe and elsewhere, but in particular from the NitroEurope Integrated Project supported by the European Commission’s 6th Framework Programme and the Nitrogen in Europe (NinE) Research Networking Programme of the European Science Foundation. With the involvement of Action 729 of the COST Programme, the necessary expertise has been gathered to drive the Assessment.

The message of 200 leading European experts from differ-ent disciplines and perspectives is surely that we need to take steps forward. Only by joining forces to face the societal chal-lenges will European research provide the scientific basis and the evidence needed for solutions. If European innovation has handed us down a nitrogen inheritance, threatening the envir-onment as a price for a solution to nourish the growing world population, it is only right that European science should lead the way in responding to the challenge.

Robert-Jan SmitsDirector General for Research,

European CommissionProfessor Marja Makarow

Chief Executive, European Science Foundation

Foreword






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Main messages

Too much nitrogen harms the environment and the economy

Over the past century humans have caused unprecedented changes to the global nitrogen cycle, converting atmospheric di-nitrogen (N2) into many reactive nitrogen (Nr) forms, doubling the total fixation of Nr globally and more than tripling it in Europe.The increased use of Nr as fertilizer allows a growing world population, but has considerable adverse effects on the environment and human health. Five key societal threats of Nr can be identified: to water quality, air quality, greenhouse balance, ecosystems and biodiversity, and soil quality.Cost–benefit analysis highlights how the overall environ-mental costs of all Nr losses in Europe (estimated at €70–€320 billion per year at current rates) outweigh the dir-ect economic benefits of Nr in agriculture. The highest soci-etal costs are associated with loss of air quality and water quality, linked to impacts on ecosystems and especially on human health.

Nitrogen cascade and budgetsThe different forms of Nr inter-convert through the environment, so that one atom of Nr may take part in many environmental effects, until it is immobilized or eventually denitrified back to N2. The fate of anthropogenic Nr can therefore be seen as a cascade of Nr forms and effects. The cascade highlights how policy responses to different Nr forms and issues are inter-related, and that a holistic approach is needed, maximizing the abatement synergies and minimizing the trade-offs.Nitrogen budgets form the basis for the development and selection of measures to reduce emissions and their effects in all environmental compartments. For instance, the

European nitrogen budget highlights the role of livestock in driving the European nitrogen cycle.

Policies and managementExisting policies related to Nr have been largely established in a fragmented way, separating Nr forms, media and sectors. Despite the efforts made over many years to reduce Nr inputs into the environment, most of the Nr-related environmental quality objectives and environmental action targets have not been achieved to date.The five societal threats and N budgets are starting points for a more-holistic management of Nr. The Assessment identifies a package of 7 key actions for overall management of the European nitrogen cycle. These key actions relate to: Agriculture (3 actions), Transport and Industry (1 action), Waste water treatment (1 action) and Societal consumption patterns (2 actions).The key actions provide an integrated package to develop and apply policy instruments. The need for such a package is emphasized by cost–benefit analysis that highlights the role of several Nr forms especially nitrogen oxides (NOx),ammonia (NH3) and Nr loss to water, in addition to nitrous oxide (N2O), in the long term.

International cooperation and communicationTackling Nr necessitates international cooperation. There are various options to implement multi-lateral environmental agreements; a possible inter-convention agreement on nitrogen needs to be further explored.Communication tools for behavioural change should be extended to nitrogen, such as calculating nitrogen ‘food-prints’. Messages should emphasize the potential health co-benefits of reducing the consumption of animal products to avoid excess above recommended dietary guidelines.

Summary for policy makers

Lead authors: Mark A. Sutton and Hans van Grinsven

Contributing authors: Gilles Billen, Albert Bleeker, Alexander F. Bouwman, Keith Bull, Jan Willem Erisman, Peringe Grennfelt, Bruna Grizzetti, Clare M. Howard, Oene Oenema, Till Spranger and Wilfried Winiwarter







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1. Why nitrogen? Concerns and the need for new solutions1. Nitrogen is an abundant element on earth, making up nearly 80% of the earth’s atmosphere. However, as atmospheric di-nitrogen (N2), it is unreactive and cannot be assimilated by most organisms. By contrast there are many reactive nitrogen (Nr)forms that are essential for life, but are naturally in very short supply. These include ammonia, nitrates, amino acids, proteins and many other forms. Until the mid nineteenth century, lim-ited availability of these Nr compounds in Europe severely con-strained both agricultural and industrial productivity [1.1, 2.1].1

2. With increasing population in the late nineteenth century, rates of biological nitrogen fixation were not sufficient for crop needs and Europe became increasingly dependent on limited sources of mined Nr (guano, saltpetre, coal). At the start of the twentieth century, several industrial processes were developed to fix N2 into Nr, the most successful being the Haber–Bosch proc-ess to produce ammonia (NH3) [1.1, 2.1].

3. Since the 1950s, Nr production has greatly increased, representing perhaps the greatest single experiment in global geoengineering [1.1]. Europe’s fertilizer needs have been met, as well as its military and industrial needs for Nr [3.2, 3.5]. In addition, high temperature combustion processes have sub-stantially increased the formation and release of nitrogen oxides (NOx) [2.4]. While the Nr shortage of the past has been solved, Europe has stored up a nitrogen inheritance of unex-pected environmental effects [1.1].

4. Europe remains a major source region for Nr produc-tion, with many of the environmental impacts being clearly visible and well studied. There is a wealth of evidence on sources, fate and impacts of Nr. However, the complexity and extent of the interactions mean that scientific understanding has become scattered and focused on individual sectors. A parallel fragmentation can be seen in environmental policies related to nitrogen, which are typically separated by media (air, land, water, etc.), by issue (climate, biodiversity, waste etc) and by Nr form [4.4, 5.3].

5. While this specialization has advanced understanding, European science and policies related to nitrogen have to a sig-nificant degree lost sight of the bigger picture. The occurrence of Nr in many different Nr forms and media, means that each com-ponent should not be considered in isolation. A more compre-hensive understanding of the nitrogen cycle is therefore needed to minimize the adverse effects of Nr in the environment, while optimizing food production and energy use [5.3].

2. Role and approach of the European Nitrogen Assessment6. A key challenge is to synthesize the science and understand-ing of nitrogen into a form that is useful to governments and society. This involves bringing the different Nr forms, discip-lines and stakeholders together.

7. The European Nitrogen Assessment (ENA) was estab-lished in response to these needs. It was coordinated by the Nitrogen in Europe (NinE) programme of the European Science Foundation, drawing on underpinning research from across Europe, but especially the NitroEurope Integrated Project co-funded by the European Commission, with input from the COST Action 729. The Assessment provides a European contribution to the International Nitrogen Initiative (INI) [1.3].

8. The lead policy audience for the Assessment is the Geneva Convention on Long-range Transboundary Air Pollution (CLRTAP), established under the auspices of the United Nations Economic Commission for Europe (UNECE). Through its Task Force on Reactive Nitrogen, the Convention has formally adopted the Assessment as a contributing activity to its work [1.3].

9. In addition to supporting CLRTAP, the Assessment is tar-geted to provide scientific and policy support to the European Union and its Member States, as well as other multi-lateral environmental agreements, including the Global Partnership on Nutrient Management facilitated by UNEP [1.5].

10. Recognizing these needs, the goal of the European Nitrogen Assessment was established: to review current scien-tific understanding of nitrogen sources, impacts and interactions across Europe, taking account of current policies and the eco-nomic costs and benefits, as a basis to inform the development of future policies at local to global scales [1.4].

11. The Assessment process was conducted through a ser-ies of five open scientific workshops between 2007 and 2009. Draft chapters were submitted to internal and external peer review [1.3].

3. Disruption of the European nitrogen cycle

Fertilizers, energy and transport: drivers for increased nitrogen inputs12. Production of Nr is a key input for agriculture and indus-try, and a persistent side-effect of combustion for energy and transport. Industrial production in Europe of Nr in 2008 was about 34 Tg per year (where 1 Tg = 1 million tonnes) of which 75% is for fertilizer and 25% for chemical industry (produc-tion of rubbers, plastics, and use in electronic, metals and oil industry) [3.5]. The trend in mineral fertilizer represents the largest change in overall Nr inputs to Europe over the past cen-tury (Figure SPM.1).

13. The combustion of fossil fuels has allowed a substantial increase in industrial production and transportation, reflected in the greatly increased emission of nitrogen oxides, which only over the last 20 years have partly been controlled. By contrast, the total contribution of crop biological nitrogen fixation has decreased significantly.

14. The provision of Nr from the Haber–Bosch process removed a major limiting factor on society, permitting sub-stantial population growth and improving human welfare.

1 References in this summary (e.g., [1.1, 11.1]) refer to chapter and section numbers of the European Nitrogen Assessment.







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However, accounting for natural sources, humans have more than doubled the supply of Nr into the environment globally [1.1], and more than tripled this supply in Europe (Figure SPM.3) [16, supplementary material].

15. As of the year 2000, Europe creates about 19 Tg per year of Nr, of which 11 Tg per year is from chemical fertiliz-ers, 3.4 Tg per year from combustion sources, 3.5 Tg per year from food and feed import and 1 Tg per year by crop biological N-fixation (BNF) (Figure SPM.3).

The nitrogen cascade16. Human production of Nr from N2 causes a cascade of intended and unintended consequences. The intended cas-cade is that each molecule of Nr contributes to soil fertility and increased yields of crops, subsequently feeding livestock and humans, allowing the formation of amino acids, proteins and

DNA. In a well managed system, the intention is for the Nr in manures and sewage to be fully recycled back through the agri-cultural system (blue arrows in Figure SPM.2).

17. Reactive nitrogen, is however, extremely mobile, with emissions from agriculture, combustion and industry lead-ing to an unintended cascade of Nr losses into the natural environment (Figure SPM.2). Once released, Nr cascades through the different media, exchanging between differ-ent Nr forms and contributing to a range of environmental effects, until it is finally denitrified back into N2. An import-ant consequence of the cascade is that the environmental impacts of Nr eventually become independent of the sources, so that nitrogen management requires a holistic approach. This is important, both to minimize ‘pollution swapping’ between different Nr forms and threats, and to maximize the potential for synergies in mitigation and adaptation strat-egies [2.6, 5.2].

Figure SPM.1 Estimated trend of anthropogenic reactive nitrogen inputs to the European Union (EU-27) [5.1] (1 Tg equals 1 million tonnes).

Figure SPM.2 Simplified view of the N-cascade, highlighting the capture of atmospheric di-nitrogen (N2) to form reactive nitrogen (Nr) by the Haber–Bosch process – the largest source of Nr in Europe. The main pollutant forms of Nr

(orange boxes) and five environmental concerns (blue boxes) are summarized. Blue arrows represent intended anthropogenic Nr flows; all the other arrows are unintended flows [1.2]. For fuller description including other Nr sources, see [5.2].







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A new nitrogen budget for Europe18. One of the tasks addressed in the European Nitrogen Assessment has been to construct a comprehensive nitrogen budget for Europe (EU-27 for the year 2000), considering each of the major flows in the nitrogen cascade [16.4]. In parallel, the estimates have also been compared with 1900 [16, supple-mentary material]. By combining all the nitrogen flows, such budgets provide improved perspective on the major drivers and the most effective control options.

19. Figure SPM.3 summarizes the European nitrogen budget in its simplest form [derived from 16.4]. The budget for 2000 shows that overall human perturbation of the nitrogen cycle is driven primarily by agricultural activities. Although the atmospheric emissions of NOx from traffic and industry contribute to many environmental effects, these emissions are dwarfed by the agricultural Nr flows.

20. It is important to note the magnitude of the European Nr flow in crop production, which is mainly supported by Nr

fertilizers. The primary use of the Nr in crops, however, is not directly to feed people: 80% of the Nr harvest in European crops provides feeds to support livestock (8.7 Tg per year plus 3.1 Tg per year in imported feeds, giving a total of 11.8 Tg per year). By comparison, human consumption of Nr is much smaller, amounting to only 2 Tg per year in crops and 2.3 Tg per year in animal products. Human use of livestock in Europe, and the consequent need for large amounts of animal feed, is there-fore the dominant human driver altering the nitrogen cycle in Europe [16.4].

21. These major intended alterations in Nr flows cause many additional unintended Nr flows (Figure SPM.3). Overall, NH3 from agriculture (3.2 Tg per year) contributes a similar

amount to emissions of Nr to the atmosphere as NOx (3.4 Tg per year). Agriculture also accounts for 70% of nitrous oxide (N2O) emissions in Europe, with total N2O emissions of 1 Tg per year. The food chain also dominates Nr losses to ground and surface waters, mainly as nitrates (NO3), with a gross load of 9.7 Tg resulting mainly from losses due to agriculture (60%) and discharges from sewage and water treatment sys-tems (40%) [16.4].

22. The comparison between 1900 and 2000 shows how each of these flows have increased, including denitrification back to N2. Denitrification is the largest and most uncertain loss, as it occurs at many different stages during the con-tinuum from soils to freshwaters and coastal seas. Although emissions of N2 are environmentally benign, they represent a waste of the substantial amounts of energy put into human production of Nr, thereby contributing indirectly to climate change and air pollution. This is in addition to the impact on climate change of N2O formed especially as a byproduct of denitrification.

Achievements and limitations of current policies23. Peak production of Nr in Europe occurred in the 1980s, which was linked to agricultural over-production and lack of emissions regulations. Since that time, the introduction of policies and other changes affecting agriculture (including the Common Agricultural Policy, Nitrates Directive and the restructuring of Eastern Europe after 1989), as well as strin-gent emission controls, e.g., for large combustion plants (EC Large Combustion Plants Directive, UNECE Sofia Protocol and Gothenburg Protocol, etc.) and the EURO standards for

Soils

Livestock& humannutrition

atmospheric N2 pool

atmosph.deposition

9.6

4

cropN2 fix

Fertilizers

0.21.9

gaseouslosses

N2 fixindustry &

traffic

0.6

Europe (EU27), around 1900.N fluxes in TgN/yr

Export byrivers tothe sea

2.1

2.1

atmosph. NH3NOxN2O

cropproduction

Losses towater

1.9

2.34

Soils

Livestock& humannutrition

atmospheric N2 pool

17.6

1

cropN2 fix

11.23.8

gaseouslosses

Europe (EU27), around 2000.N fluxes in TgN/yr

Export byrivers tothe sea

cropproduction

Losses towater

3.8

4.513.5

3.4

9.7

Net atmosphericexport2.4

3.5 Net import offood & feed

atmosph. NH3NOxN2O

atmosph.deposition

N2 fixindustry& traffic Fertilizers

Figure SPM.3 Simplified comparison of the European nitrogen cycle (EU-27) between 1900 and 2000. Blue arrows show intended anthropogenic nitrogen flows; orange arrows show unintended nitrogen flows; green arrows represent the nearly closed nitrogen cycle of natural terrestrial systems [16.4 and 16 supplementary material].







xxviii

road transport vehicles, have led to decreases in the emissions (Figure SPM.4) [4.4].

24. Overall, emissions of combustion NOx have reduced by ~30% since 1990, but much greater NOx reductions per unit out-put have been achieved. These have been offset by an increase in traffic and energy consumption. The net emission reduction is therefore a clear example of decoupling, as emissions would have increased by over 30% if no measures had been imple-mented. The extent of success of the technical measures can be in part attributed to the involvement of a small number of play-ers (e.g., electricity supply industry, vehicle manufacturers) and the fact that the costs of these measures could be easily trans-ferred to consumers [4.5].

25. Agricultural measures have resulted in only a mod-est reduction in total agricultural Nr inputs for the EU-27 of ~15% (Figure SPM.1). This small overall reduction is reflected in the trends in NH3 emissions (Figure SPM.4). Most of the reductions that have been achieved to date can be attributed to reductions in fertilizer use and livestock numbers, especially in Eastern Europe after 1989. Although management improve-ments will have contributed to reduced emissions (e.g., nitrate leaching and loss to marine areas), there has as yet been little quantitative achievement of measures to reduce N2O and NH3

emissions from agriculture on a European scale. The fact that current Nr emission reduction policies in agriculture (e.g., Nitrates Directive, Oslo and Paris Commission for the protec-tion of the North East Atlantic, UNECE Gothenburg Protocol and National Emissions Ceilings Directive) have only made lim-ited progress can be linked in part to the large number of diverse actors (including many small farms), the diffuse nature of the Nr emission sources, and the challenge of passing any perceived costs onto consumers [4.5]. As a consequence, agriculture is the sector with the largest remaining emission reduction potential.

26. Several instances of pollution swapping in Nr control have been observed. These include the introduction of three way catalysts in vehicles, which increased NH3 and N2O emis-sions (although overall Nr emissions were still greatly reduced), and the implementation of the Nitrates Directive, prohibiting wintertime manure spreading, which has led to a new peak in springtime NH3 emisssions [9.2].

4. The benefits and efficiency of nitrogen in agriculture

Nitrogen fertilizers feed Europe27. There is no doubt that human production of Nr has greatly contributed to the increase in productivity of agricultural land. Without anthropogenic Nr, a hectare of good agricultural land in Europe, with no other growth limitations, can produce about 2 tonne per ha of cereal annually. With typical additional inputs from biological nitrogen fixation (BNF), it can produce about 4–6 tonne per ha, and with addition of chemical fertil-izer about 8–10 tonne per ha. Synthetic Nr fertilizer has been estimated to sustain nearly 50% of the world’s population, and is essential for the EU to be largely self-sufficient in cereals. For pork, poultry and egg production, Europe strongly depends on soybean imports from America [3.1].

28. Agronomic efficiency provides an indicator of the Nr-benefit to the farmer (kg crop production per kg applied N). Typically, fertilizer rates in the eastern EU Member States are up to four times lower than in the 15 ‘old’ Member States, but agronomic efficiencies are comparable (Figure SPM.5). The use of Nr is profitable as there is a robust financial return of €2–5 on every euro invested in Nr fertilizer, depending on the market price of cereals and fertilizer [3.6].

Grain and meat production considerably differ in their Nr losses to the environment29. The nitrogen recovery (kg N taken up by a crop per kg applied N) provides a measure of environmental N-loss in crop production. For cereals it varies 30%–60% across Europe, indi-cating that 40%–70% of the fertilizer Nr applied is lost to the atmosphere or the hydrosphere [3.2].

30. The nitrogen recovery in animal farming is inherently lower than in crops, with only 10–50% of Nr in feed being retained in liveweight and 5%–40% in the edible weight (Figure SPM.6). Accounting for the additional Nr losses in feed production, the overall efficiency of Nr use for meat production is around half these values. For this reason, the full chain of animal protein production

Figure SPM.4 Estimated trends in European reactive nitrogen emissions between 1900 and 2000 (EU-27) [5.1].







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generates much more losses to the environment than plant protein production.

31. About one third (7.1 Tg per year in 2000) of the total farm input of Nr to soil comes from animal manures. This rep-resents about two thirds of the Nr from animal feeds, while the fraction of Nr in animal manures that is lost to the environment is typically double that of mineral Nr fertilizer, highlighting the importance of proper measures to maximize the effectiveness of manure reuse [3.2].

Variation in nitrogen use efficiency highlights the potential for solutions32. The overall efficiency of European agriculture (ratio of N in food produced to the sum of synthetic N fertilizer used plus food and feed imports) is about 30% since 2000 [derived from 16.4, see Figure SPM.3]. The wide variety in N application rates and nitrogen use efficiency across Europe indicates that there is a huge scope to improve resource efficiency and reduce envir-onmental effects (Figure SPM.5).

33. In the EU, protein consumption exceeds recommended intake by 70% [26.3] and the share of animal proteins in this total is increasing. Even a minor change in human diet, with less animal protein consumption (or protein from more effi-cient animals), would significantly affect the European nitro-gen cycle.

5. The key societal threats of excess nitrogen34. From a longer list of around 20 concerns, the Assessment identifies five key societal threats associated with excess Nr in the environment: Water quality, Air quality, Greenhouse bal-ance, Ecosystems and biodiversity, and Soil quality. Together, these threats can be easily remembered by an acronym as the ‘WAGES’ of excess nitrogen, and visualized by analogy to the four ‘elements’ (water, air, fire, earth) and quintessence of clas-sical Greek cosmology (Figure SPM.7). These five threats pro-vide a framework that incorporates almost all issues related to the longer list of concerns associated with excess Nr [5.4].

Nitrogen as a threat to European water quality35. Water pollution by Nr causes eutrophication and acidifica-tion in fresh waters [7.4, 8.8]. Estuaries, their adjacent coast-lines and (near) inland seas are also affected by eutrophication from Nr with inputs to the coastal zone being four times the natural background [13.7]. Biodiversity loss, toxic algal blooms and dead zones (fish kill) are examples of effects [8.8]. Nitrate levels in freshwaters across most of Europe greatly exceed a threshold of 1.5 to 2 mg Nr per litre, above which waterbodies may suffer biodiversity loss [7.5, 17.3].

36. High nitrate concentrations in drinking water are con-sidered dangerous for human health, as they might cause can-cers and (albeit rarely) infant methaemoglobinaemia. About 3% of the population in EU-15 is potentially exposed to levels exceeding the standard for drinking water of 50 mg NO3 per litre (11.2 mg Nr per litre) and 6% exceeding 25 mg NO3 per litre [17.3]. This may cause 3% increase of incidence of colon cancer, but nitrate is also considered to be beneficial to cardio-vascular health [22.3].

37. Although aquatic eutrophication has decreased to some extent since the 1980s, agreed international policies have not been fully implemented. In addition, increasing nitrate in groundwaters threatens the long-term quality of the resource, due to long residence times in aquifers [7.5, 17.2]. Achieving substantial progress at the European scale requires integration of sectoral policies, reducing overall inputs of Nr to watersheds [4.5, 13.7, 17.5].

Nitrogen as a threat to European air quality38. Air pollution by nitrogen oxides (NOx) and ammonia (NH3) causes formation of secondary particulate matter (PM), while emissions of NOx also increase levels of nitrogen dioxide

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Figure SPM.5 Variation of nitrogen fertilizer use on winter wheat across the European Union (EU 15: blue, EU 12: red) around the year 2000. The variation indicates that there is substantial scope to increase performance and reduce environmental effects [3.2].

Figure SPM.6 Range of Nr recovery efficiencies in farm animal production in Europe (kg N in edible weight per kg N in animal feed) [3.4, 10.4, 26.3], see also supplementary material for Chapter 3. A higher recovery efficiency is indicative of a smaller nitrogen footprint. Accounting for the full chain from fertilizer application to Nr in edible produce, overall nitrogen use efficiency in animal production for the EU-27 is around 15%–17% [3, 10, supplementary material]. While intensive systems tend to have a higher Nr recovery, they also tend to have larger Nr losses per ha unless efforts are taken to reduce emissions [10.4].







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(NO2) and tropospheric ozone (O3). All of these are causes for respiratory problems and cancers for humans, while ozone causes damage to crops and other vegetation, as well as to buildings and other cultural heritage [18.2, 18.5].

39. Models estimate that PM contributes to 300–400 thou-sand premature deaths annually in Europe leading to a reduc-tion in life expectancy due to PM of 6–12 months across most of central Europe. Nr contributes up to 30%–70% of the PM by mass [18.3, 18.5]. However, the individual contributions of NOx- and Nr-containing aerosol to human health effects of air pollution remain uncertain [18.2].

40. Although NOx emission decreases have reduced peak O3 concentrations, background tropospheric O3 concentrations continue to increase. By comparison to the limited progress in reducing NOx emissions, there has been even less success in controlling agricultural NH3 emissions, which therefore con-tribute to an increasing share of the European air pollution burden [4.5, 18.6].

Nitrogen as a threat to European greenhouse balance41. Reactive nitrogen emissions have both warming and cool-ing effects on climate. The main warming components are increasing concentrations of nitrous oxide (N2O) and tropo-spheric ozone, which are both greenhouse gases. The main cool-ing effects are atmospheric Nr deposition presently increasing CO2 removal from the atmosphere by forests, and the forma-tion of Nr containing aerosol, which scatter light and encourage cloud formation [19].

42. Overall, European Nr emissions are estimated to have a net cooling effect on climate of −16 mW per m2, with the uncertainty bounds ranging from substantial cooling to a small net warming (−47 to +15 mW per m2). The largest uncertain-ties concern the aerosol and Nr fertilization effects, and the esti-mation of the European contributions within the global context [19.6]. The estimate of the Intergovernmental Panel on Climate Change (IPCC) for indirect N2O emissions from Nr deposition is considered to be an underestimate by at least a factor of 2 [6.6, 19.6].

43. There are many opportunities for ‘smart management’, increasing the net cooling effect of Nr by reducing warming effects at the same time as other threats, e.g., by linking N and C cycles to mitigate greenhouse gas emissions through improved nitrogen use efficiency [19.6].

Nitrogen as a threat to European terrestrial ecosystems and biodiversity44. Atmospheric Nr deposition encourages plants favouring high Nr supply or more acidic conditions to out-compete a larger number of sensitive species, threatening biodiversity across Europe. The most vulnerable habitats are those with species adapted to low nutrient levels or poorly buffered against acidification. In addition to eutrophication, atmos-pheric Nr causes direct foliar damage, acidification and increased susceptibility to pathogens [20.3].

45. Although there are uncertainties in the relative effects of atmospheric nitrate (NO3

−) versus ammonium (NH4+), gas-

eous ammonia (NH3) can be particularly harmful to vegetation, causing foliar damage especially to lower plants [20.3]. This emphasizes the threat to semi-natural habitats occurring in agricultural landscapes [9.6, 11.5]. While uncertain, Nr depos-ition is expected to act synergistically with climate change and ground-level ozone [20.2].

46. Thresholds for atmospheric concentrations and depos-ition of Nr components to semi-natural habitats are exceeded across much of Europe, and will continue to be exceeded under current projections of Nr emissions. In order to achieve ecosys-tem recovery, further reductions of NH3 and NOx emissions are needed [20.5]. Due to cumulative effects of Nr inputs and long time-lags, rates of ecosystem recovery are expected to be slow, and in some cases may require active management interven-tion in the affected habitats [20.5].

Nitrogen as a threat to European soil quality47. Soil integrates many of the other Nr effects, highlighting their interlinked nature. The major Nr threats on soil quality are soil acidification, changes in soil organic matter content and loss of soil biodiversity. Soil acidification can occur from the deposition of both oxidized and reduced Nr, resulting from NOx and NH3 emissions, reducing forest growth and leading to leaching of heavy metals [21.3]. High levels of Nr deposition to natural peatlands risk losing carbon stocks through interac-tions with plant species changes, although this effect is poorly quantified [6.6, 19.4].

Figure SPM.7 Summary of the five key societal threats of excess reactive nitrogen, drawn in analogy to the ‘elements’ of classical Greek cosmology. The main chemical forms associated with each threat are shown [5.4]. Photo sources: Shutterstock.com and garysmithphotography.co.uk.







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48. Addition of Nr typically has a beneficial effect in agri-cultural soils, enhancing fertility and soil organic matter [6.4 , 21.3]. However, Nr losses increase, while some soil fungi and N-fixing bacteria are reduced by high N availability. The inter-actions between Nr and soil biodiversity, soil fertility and Nr

emissions are not well understood [21.3].49. European forest soils are projected to become less

acidic within a few decades, mainly as a result of reduced SO2

and NOx emissions. Ammonia emissions have only decreased slightly and NHx is increasingly dominating soil acidification effects over large parts of Europe [20.3, 21.4].

6. The economics of nitrogen in the environment

Estimated loss of welfare due to nitrogen emissions in Europe50. The social costs of the adverse impacts of Nr in the European environment are estimated. Expressed as € per kg of Nr emission, the highest values are associated with air pollution effects of NOx on human health (€10–€30 per kg), followed by the effects of Nr loss to water on aquatic ecosystems (€5–€20 per kg) and the effects of NH3 on human health through par-ticulate matter (€2–€20 per kg). The smallest values are esti-mated for the effects of nitrates in drinking water on human health (€0–€4 per kg) and the effect of N2O on human health by depleting stratospheric ozone (€1–€3 per kg) [22.6].

51. Combining these costs with the total amount of emis-sions for each main Nr form, provides a first estimate of the annual Nr-related damage in EU-27 (Figure SPM.8). The overall costs are estimated at €70–€320 billion per year, of which 75% is related to air pollution effects and 60% to human health. The total damage cost equates to €150–€750 per person, or 1–4% of the average European income [22.6] and is about twice as high as the present ‘Willingness to Pay’ to control global warming by carbon emissions trading [22.6].

52. Environmental damage related to Nr effects from agri-culture in the EU-27 was estimated at €20–€150 billion per year. This can be compared with a benefit of N-fertilizer for farmers of €10–€100 billion per year, with considerable uncer-tainty about long-term N-benefits for crop yield [22.6].

53. Apart from the uncertainties inherent in valuing the environment, including the use of ‘willingness to pay’ approaches for ecosystem services, the main uncertainties in these estimates concern the relative share of Nr in PM to human health effects and of Nr to freshwater eutrophication effects [22.6].

Future European nitrogen mitigation and scenarios54. Internalizing the environmental costs for N-intensive agri-culture in North Western Europe provides economically opti-mal annual Nr application rates that are about 50 kg per ha (30%) lower than the private economic optimum rate for the

farmer. This highlights the importance of increasing nitrogen use efficiency and accounting for external effects on the envir-onment in providing N-recommendations to farmers [22.6].

55. The results also highlight the small overall cost due to N2O emissions compared with NOx, NH3 emissions and Nr

losses to water (Figure SPM.8). Although unit costs of N2O, at €6–€18 per kg Nr emitted, are similar to the other issues, N2Oemissions are much smaller (para. 21), so that total European damage costs due to N2O are much less than from the other Nr

forms. Based on the ‘willingness to pay’ approach and current values, this indicates that the highest policy priority be put on controlling European NOx and NH3 emissions to air and Nr

losses to water, as compared with the control of N2O emissions. It is important to target measures that have maximum synergy, reducing emissions of all Nr forms and impacts simultaneously. However, where some measures involve limited trade-offs between Nr (‘pollutant swapping’), Figure SPM.8 indicates that further control of NOx, NH3 and Nr to water would be justified economically even if a proportionate percentage increase in N2O emission were to occur.

56. Estimated costs of technical measures to reduce emis-sions of NOx, NH3 and N2O are available in the IIASA GAINS model. Based on these estimates, future scenarios up to 2030 compare current reduction plans with maximum feasible reduc-tion and a cost optimization approach. This comparison indi-cates substantial scope for further reductions in NOx and NH3

emissions, supporting the case for revision of the Gothenburg Protocol [24.6]. Although not assessed here, preliminary indi-cations suggest that costs of NH3 abatement measures (€ per kg Nr) are cheaper than previously estimated, being the subject of ongoing review.2

Figure SPM.8 Estimated environmental costs due to reactive nitrogen emissions to air and to water in the EU-27 [22.6].

2 United Nations Economic Commission for Europe (2010), Options for Revising the 1999 Gothenburg Protocol to Abate Acidification, Eutrophication and Ground-level Ozone: Reactive Nitrogen (ECE/EB.AIR/WG.5/2010/13).






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