Spain case study: Lerma Gully Basin (Zaragoza)

The study zone is the hydrological basin of the upper section of Lerma Gully, placed inside the municipality of Ejea de los Caballeros (Zaragoza, Spain). It is located on the left bank of the middle Ebro River Valley (which covers a great proportion of the north-eastern area of Spain). The area of the basin is 7.38 km2, with about 4.5 km long (from East-Southeast to West-Northwest) and around 2 km wide. Altitudes range from 335 to 495 m above sea level. The Lerma Gully waters drain to the Arba River, one of the main tributaries of the Ebro River.
In the 2000s, approximately 20,000 ha of rainfed croplands in the Arba River Basin were transformed into irrigated agricultural land, leading to a progressive increase in the use of fertilizers in the area (compound and liquid NPK fertilizers). The Lerma Gully Basin, a small hydrogeological basin representative of the area, in which 48% of the surface shifted to irrigated agriculture, has been monitored since 2004 to assess the effects of this transformation on the water balance and the salt and NO3–-N exports. In general, the implementation of irrigation implied a three-fold increase in N export to the receiving Arba River, which was the first surface water body in the Ebro River Basin to be declared affected by NO3– pollution according to the Nitrates Directive 91/676/EEC. In this project, a Nature Based Solution consisting in a surface flow Constructed Wetland will be adopted in order to diminish the release of NO3– from the Lerma Gully Basin to the Arba River.

Issues to be addressed

Adopting a Nature Based Solution consisting in a surface flow Constructed Wetland in order to diminish the release of nitrates from the Lerma gully, polluted by agricultural return flows, to the Arba River Basin.
Improvement of the CW heterotrophic denitrification efficiency by biostimulation: testing local industry by-products (at laboratory and field scale) as cost-effective and sustainable electron donor supplies.

Solutions and Technologies implemented in the case study area

CONSTRUCTED WETLAND (CW)

CW are low cost, promising nature-based solution systems specifically designed to remove diverse pollutants from water by using mostly the processes that occur in natural wetlands, but within a more controlled environment.

Denitrification is generally considered to be the major NO3- removal process in CW. The nutrients reduction processes in the CW are similar to those in the BR. Additionally, CW can also be useful for the removal of other contaminants, such as pesticides, pharmaceuticals, etc. In this project, a CWwill be adopted aiming to attenuate the release of NO3- from the Lerma Basin to the Arba River.

The surface water of the Lerma gully, polluted by the agricultural return flows (namely, the Lerma gully is feeded by local shallow perched aquifers contaminated by agricultural return flows), will be partially diverted towards the CW, to be afterwards given back to the gully after the treatment.

The system, built on 2013 and being widened and modififed along time – will rely on: i) Surface CW: 50% of aerobic zone with emergent macrophytes (Typha and Phragmites ), working as natural green filter; ii) Subsurface CW: 50% area filled with gravel, where higher nutrients removal efficiency is expected because of prevailing anoxic conditions. Local dairy industry by-products will be tested at laboratory and field scale as cost-effective and sustainable electron donor supplies to promote heterotrophic denitrification.

Expected impacts

Development of a site-specific solution to reduce nitrate contamination in water, namely by interception and removal of nitrates before they reach the final natural receiving water body. Enhancing circular economy, with the use of agri-food industry by-products to promote denitrification.

About the partner

The Universitat de Barcelona (UB), founded in 1450, is a public university devoted to higher education and research, engaging with society and actively promoting knowledge transfer. The UB boasts of a large and growing community of almost 6.200 teachers and researchers, and 2.400 administrative staff, and offers teaching to more than 76.000 students each year. UB is ranked as the 1st Spanish university in the World University Ranking 2024 and 134 worldwide, managing in average 150 European projects per year. UB is currently the only Spanish university that is a member of the prestigious League of European Research Universities (LERU), is granted since 2015 by the European Commission with the “HR (Human Resources) Excellence in Research Award”, and coordinates the CHARM-EU, one of the first university alliances aimed at creating a new European university model.
 
Within UB, the Research Group “MineralogiaAplicada, GeoquímicaiHidrogeologia” (MAGH), recognized as a consolidated research group and supported by the Catalan Government continuously from 1995 to the present, works on topics related to Geochemistry, Mineralogy, Hydrochemistry, Environmental contamination, and Water-Rock interaction. During the last five years, the group published more than 200 scientific publications (179 in SCI journals) and has participated in 9 European projects.
 
The Group “MAiMA – Isòtopsestables i Mineralogia”, being the scientific knowledge and technology transfer section of MAGH Group, will be directly involved in NPP-SOL. The personnel involved belongs to the Department of Mineralogia, PetrologiaiGeologiaAplicadaat the Facultat de Ciències de la Terra of the UB. MAiMA holds an interdisciplinary team of scientists, experts in different scientific areas, such as isotope geochemistry, geochemistry, hydrogeology, hydrology, analytical chemistry, mineralogy and ore deposits.
With more than 25 years’ experience, it offers customized solutions to problems related to environmental contamination, authentication of agro-alimentary products and mineral durability in civil works to the private sector, public administrations, and society.
Namely, within the environmental applications of isotopic geochemistry and mineralogy, MAiMA focuses on the identification of the origin of inorganic/organic contaminants (nitrogen and sulphur compounds, volatile organic compounds, pesticides, etc.) and on the evaluation of the efficiency of natural and induced attenuation of contaminants at both laboratory and field scale, including Nature Based Solutions (experience in: biostimulation, constructed wetlands, permeable reactive barriers, in-situ chemical oxidation ISCO, etc.).
MAiMA has obtained more than 25 continuous competitive projects from the Spanish Government, 7 European projects, and since 2018 is recognized by the prestigious TECNIO certification from the Government of Catalonia (Agencia para la Competitividad de la Empresa – ACCIÓ) to the most qualified agents involved in technology transfer processes.
The MAiMA Group has its own infrastructure and access to the equipment of the Scientific and Technical Centers of the UB (CCiT-UB) to carry out routine chemical analyses, samples’ preparation, and isotopic and multi-isotopic analysis of C, N, S, Cl, H, O, B, Sr among others, and specific compound isotopic analysis (CSIA). MAiMA is also responsible for the development and implementation of isotopic methodology for extraction/preconcentration of various compounds in different matrices for isotopic analysis.

Beneficiaries

Society and biodiversity in general, since the ultimate objective is to diminish the concentration of nitrate dissolved in the surface waters of Lerma gully, Arba river and Ebro river. According to it, if the efficiency of the CW as nitrate preventing-pollution technology will be validated, the implementation of other similar facilities in other basins affected by agricultural contamination would also be a benefit for society in general. Finally, even if it goes beyond the direct impact of UB-MAiMA activities, the farmers will benefit of the improved farm practices found out during the project.

Stakeholders involved

Spanish Geological Survey (IGME, Instituto Geológico y Minero de España)
Cooperativa de Agricultores “Virgen de la Oliva”
Community of Irrigators nº XI of the Bardenas Canal
Confederación Hidrográfica del Ebro (CHE)
Comunidad General Canal de Bardenas
Quesería Biota (Cheese factory Biota)
Centro Gestor de Purines (Slurry Management Center)

Related news

Explore this Pilot area

Scroll to Top