Héctor García-Gómez

Agriculture-induced increase in nitrate concentrations in stream waters of a large Mediterranean catchment over 25 years (1981―2005)

Anthropogenic activities influence past and present nitrate levels recorded in European stream waters, posing a threat to aquatic biota and human beings. Scarce information on temporal trends of nitrate concentration and its causes is available for Mediterranean catchments. This study presents the evolution of nitrate concentrations over 25 years in stream waters of the Ebro River Basin (Spain), a large Mediterranean catchment involving 85,566 km(2). Nitrate concentration increased with time in 46% of the 65 sites involved in the study. Agricultural cover of 30 hydrologically independent sub-catchments was the main land use related to nitrate concentration (R(2)=0.69). Throughout the 25 year-period, the sites showing increased nitrate concentrations with time (trend sites) also presented an enhanced influence of agricultural cover on nitrate concentrations along the time frame of the study. As a result of these temporal changes, at the end of the studied period nitrate concentrations in stream waters responded similarly to agricultural cover in both trend and non-trend sites, showing non significant differences in the slope of the resultant regression models. At this time, agricultural cover explained 82% of the variability found in nitrate levels. If these trends remain unchanged, in 2015 many of the water bodies considered in this study would not comply with the requirements of the European Union Water Framework Directive (WFD). Therefore management decisions, mainly associated to agricultural practices, should be implemented as soon as possible at the catchment level to meet WFD objectives.

Nitrogen deposition in Spain: Modeled patterns and threatened habitats within the Natura 2000 network

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 suitability 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 NO3(-) and NH4(+) estimated with EMEP and CHIMERE model systems were compared with measured data for the period 2005-2008 obtained from different monitoring networks in Spain. Wet N deposition was acceptably predicted by both models, showing better results 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) nitrogen 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 alpine 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.

Depósito atmosférico de nitrógeno en España y evaluación del riesgo de efectos en los hábitats terrestres de la Red de Parques Nacionales

Rocío Alonso Miguel Álvarez Cobelas Jose Manuel Álvarez-Martínez Mariano Amoroso Enrique Andivia Gabriel Arellano Cristina Armas María Arróniz Crespo Anna Avila Isabel Banos-González Eulogio Bedmar Raquel Benavides Marta Benito Garzón Juan A. Blanco Francisco Javier Bonet García Raphael Boulay Santiago Fernando Burneo Francisco Cabezas Rafael Calama Silvia Calvo Aranda Julio A. Camargo Daisy Cárate-Tandalla José A. Carreira de la Fuente Myriam Catalá Miquel De Cáceres Pilar de la Rua Thibaut Dominique Delsinne Dennis Denis Lucía DeSoto Suárez María T. Domínguez David A. Donoso David A Donoso Jorge Durán María José Endara Blanca Figueroa-Rangel Rubén G. Mateo José M. García del Barrio Enrique García de la Riva Ana I. García-Cervigón Morales Héctor García-Gómez Óscar Godoy Uriel Hernandez Gomez Lorena Gémez Aparicio Penélope González José González Novoa Manuela González Suárez Daniel Griffith Roberto José Guerrero David Gutiérrez Xavier Haro Carrión Laura Hernández Mateo Javier Herrero Asier Herrero Méndez Sheila Izquieta Rojano Luis Lassaletta John Lattke Alex Leverkus Francisco Lloret Jorge Lozano Yudi Lozano Manuel Macía Jaime Madrigal González Esteban Manrique Santiago Martín Alcón Pilar Martín Isabel Javier Martínez Abaigar Jesús Martínez Fernández José Luis Martínez Menéndez Isabel Martínez Moreno Francisco Javier Martínez Vega Marcos Méndez Iglesias Rubén Milla Marcos Miñarro Daniel Moya Navarro Sven Mutke Rafael Ma Navarro Cerrillo Francisco Bruno Navarro Reyes Susana Ochoa Gaona Raúl Ochoa Hueso Daniel Paredes Mauricio Parra Quijano Sergio Pérez Guerrero Carolina Puerta Piñero Neptalí Ramírez-Marcial José V. Roces Díaz Alexandra Rodríguez Carlos Rodríguez Osorio Itziar Rodríguez Urbieta Susana Rodríguez-Echeverría Pere Rovira Paloma Ruiz-Benito Asunción Saldaña Ángela Sánchez-Miranda Fábio Suzart de Albuquerque María Fernanda Tapia-Armijos Jerónimo Torres-Porras María Triviño Raúl Vaca Alejandro Valdecantos Jordi Vayreda Alejandro Velázquez Martínez Albert Vila-Cabrera Rafael Villar Francisco Javier Zamora Camacho Carlos Zamorano-Elgueta Galo Zapata Ríos Lista de revisores que han completado revisiones en el año 2016Visconti, F., de Paz, J.M. 2017. Estimation of the potential CO 2 sequestration and emission capacity of the agricultural soils of the Valencian Community. Ecosistemas 26(1): 91-100. Doi.: 10.7818/ECOS.2017.26-1.15 Agricultural soils have capacity to sequester CO 2 in the form of organic matter. However, this capacity has hardly been quantified and mapped for large territories and with a wide variety of crops, such as the Valencian Community. This task is required to properly size the role of agriculture in any strategy to mitigate climate change. In this paper a first estimate of the potential CO 2 sequestration and emission capacity of the agricultural soils of the Valencian Community down to 20 cm depth has been made. This estimate has been carried out based on the average and spatial variability of the agricultural soil organic matter content in homogeneous agro-ecological zones in climate, soil class and land use, and using GIS, geostatistics and map algebra techniques. The sequestration and emission capacities were found to be 24.0 and 22.0 Mt of carbon, respectively. These values are equivalent to roughly ± 8 years of carbon emissions by use of fossil fuels in the Community itself. This sequestering capacity, which could be reached in 15 to 100 years with the global adoption of management practices that foster soil organic matter accumulation, has an important but insufficient effect compared to the current emission rate. In any case, increasing carbon sequestration in soils, either through management improvement or through organic matter incorporation programs, is very important both to improve sequestration capacity and even more to adapt agroecosystems to climate change.

Joining empirical and modelling approaches to estimate dry deposition of nitrogen in Mediterranean forests

In Mediterranean areas, dry deposition is a major component of the total atmospheric N input to natural habitats, particularly to forest ecosystems. An innovative approach, combining the empirical inferential method (EIM) for surface deposition of NO3- and NH4+ with stomatal uptake of NH3, HNO3 and NO2 derived from the DO3SE (Deposition of Ozone and Stomatal Exchange) model, was used to estimate total dry deposition of inorganic N air pollutants in four holm oak forests under Mediterranean conditions in Spain. The estimated total deposition varied among the sites and matched the geographical patterns previously found in model estimates: higher deposition was determined at the northern site (28.9 kg N ha-1 year-1) and at the northeastern sites (17.8 and 12.5 kg N ha-1 year-1) than at the central-Spain site (9.4 kg N ha-1 year-1). On average, the estimated dry deposition of atmospheric N represented 77% ± 2% of the total deposition of N, of which surface deposition of gaseous and particulate atmospheric N averaged 10.0 ± 2.9 kg N ha-1 year-1 for the four sites (58% of the total deposition), and stomatal deposition of N gases averaged 3.3 ± 0.8 kg N ha-1 year-1 (19% of the total deposition). Deposition of atmospheric inorganic N was dominated by the surface deposition of oxidized N in all the forests (means of 54% and 42% of the dry and total deposition, respectively). The relative contribution of NO2 to dry deposition averaged from 19% in the peri-urban forests to 11% in the most natural site. During the monitoring period, the empirical critical loads provisionally proposed for ecosystem protection (10-20 kg N ha-1 year-1) was exceeded in three of the four studied forests.