Nitrogen deposition in Spain: Modeled patterns and threatened habitats within the Natura 2000 network H. García-Gómez a, ⁎, J.L. Garrido a , M.G. Vivanco a , L. Lassaletta b , I. Rábago a , A. Àvila c , S. Tsyro d , G. Sánchez e , A. González Ortiz f , I. González-Fernández a , R. Alonso a a Atmospheric Pollution Division, CIEMAT, Av. Complutense 40, Madrid 28040, Spain b CNRS/Université Pierre et Marie Curie, UMR Sisyphe, 4 Place Jussieu, Paris 75005, France c CREAF (Center for Ecological Research and Forestry Applications), Universitat Autònoma de Barcelona, Bellaterra 08193, Spain d MSC-W of EMEP, Norwegian Meteorological Institute, Henrik Mohns plass 1, Oslo 0313, Norway e Spanish Ministry of Agriculture, Food and Environment (ICP Forests), c/Ríos Rosas 24-6°, Madrid 28003, Spain f Spanish Ministry of Agriculture, Food and Environment (Air Quality and Industrial Environment), Pza. S. Juan de la Cruz, s/n, Madrid 28071, Spain HIGHLIGHTS • CHIMERE and EMEP models acceptably estimate atmospheric N wet deposition in Spain. • Total (wet + dry) atmospheric N deposition in Spain in 2008 was up to 19–23 kg N ha -1 . • Natural grasslands are the habitats most threatened by N deposition. • Biodiversity conservation in 3–7% of the assessed area could be threatened by N deposition. • Habitats in mountain areas are particularly threatened by N deposition. abstract article info Article history: Received 20 December 2013 Received in revised form 13 March 2014 Accepted 23 March 2014 Available online xxxx Editor: Charlotte Poschenrieder Keywords: Nitrogen deposition Air quality model Monitoring network Critical load exceedance Natura 2000 network Alpine grasslands The Mediterranean Basin presents an extraordinary biological richness but very little information is available on the threat that air pollution, and in particular reactive nitrogen (N), can pose to biodiversity and ecosystem functioning. This study represents the first approach to assess the risk of N enrichment effects on Spanish ecosystems. The suit- ability of EMEP and CHIMERE air quality model systems as tools to identify those areas where effects of atmospheric N deposition could be occurring was tested. For this analysis, wet deposition of NO 3 - and NH 4 + estimated with EMEP and CHIMERE model systems were compared with measured data for the period 2005–2008 obtained from differ- ent monitoring networks in Spain. Wet N deposition was acceptably predicted by both models, showing better re- sults for oxidized than for reduced nitrogen, particularly when using CHIMERE. Both models estimated higher wet deposition values in northern and northeastern Spain, and decreasing along a NE–SW axis. Total (wet + dry) nitro- gen deposition in 2008 reached maxima values of 19.4 and 23.0 kg N ha -1 year -1 using EMEP and CHIMERE models respectively. Total N deposition was used to estimate the exceedance of N empirical critical loads in the Natura 2000 network. Grassland habitats proved to be the most threatened group, particularly in the northern al- pine area, pointing out that biodiversity conservation in these protected areas could be endangered by N deposition. Other valuable mountain ecosystems can be also threatened, indicating the need to extend atmospheric deposition monitoring networks to higher altitudes in Spain. © 2014 Elsevier B.V. All rights reserved. 1. Introduction The global biogeochemical cycle of nitrogen (N) has been deeply altered by human activities to the extent that the planetary boundary for human safe operating has long been crossed (Rockström et al., 2009). Anthropogenic reactive nitrogen (N r ) circulates across different compartments (atmosphere, hydrosphere and terrestrial ecosystems) inducing a cascade of environmental effects, such as tropospheric ozone Science of the Total Environment 485–486 (2014) 450–460 ⁎ Corresponding author. Tel.: +34 913466556; fax: +34 913466121. E-mail addresses: hector.garcia@ciemat.es (H. García-Gómez), juanluis.garrido@ciemat.es (J.L. Garrido), m.garcia@ciemat.es (M.G. Vivanco), lassalet@bio.ucm.es (L. Lassaletta), isaura.rabago@ciemat.es (I. Rábago), anna.avila@uab.es (A. Àvila), svetlana.tsyro@met.no (S. Tsyro), GSanchez@magrama.es (G. Sánchez), Alberto.Gonzalez@eea.europa.eu (A. González Ortiz), ignacio.gonzalez@ciemat.es (I. González-Fernández), rocio.alonso@ciemat.es (R. Alonso). http://dx.doi.org/10.1016/j.scitotenv.2014.03.112 0048-9697/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv