An exemplary environmental study in the watershed of river Águeda

José Pichel Andrés/DICYT The Institute of Natural Resources and Agrobiology (IRNASA, a center that belongs to CSIC), The European University Miguel de Cervantes of Valladolid and The Polytechnic Institute of Castelo Branco have developed an environmental characterization project and analysis of natural risks in the watershed of river Águeda, which is located mostly in the Southwest of the province of Salamanca, except from a small part in Portugal. The results, which are collected in the publication ‘Cuenca del río Águeda: un territorio para dos países’ (‘The watershed of river Águeda: a territory for two countries’) show high levels of arsenic and gamma radiation in some parts, although it is not supposed to be a serious health and environmental problem.

According to a scientific point of view, the most important fact is that it is a pilot project which may be used as a reference in the study of other larger watersheds or with greater contamination problems. “It is a multidisciplinary project which has the objective of designing an impact and environmental risk project comparable to other border watersheds”, said IRNASA researcher María Jesús Sánchez Martín to DiCYT.

Though, according to a more practical and immediate interest, the research has contributed to valuable data for territory management, especially about pinpointed contamination of elements like arsenic. In this area there are about 60 abandoned mineral mines like tungsten and tin and, as a sub product of this exploitation, arsenic, a toxic element that may enter at the local food chain.

According to the scientists, the problem is pinpointed, especially in mines like Navasfrías, Barquilla, El Payo or Puerto Seguro. Consequently, it is not an important risk for the population even though these places should be fenced in to hinder shepherding in these areas. Even in Navasfrías a recreational area for visitors was set up on contaminated ground.

The researchers have collected more than 200 samples in superficial and underground waters for analytic control, especially of arsenic and uranium and agricultural pesticides. In some cases, especially because of the time of the year, contamination from agricultural activities due to the use of pesticides in higher levels than those allowed for water drinking has also been found; nevertheless, in general, the impact of these compounds is not relevant.

Uranium and gamma radiation

The presence of uranium is much more relevant since this area is rich in this element which is used as nuclear fuel. Particularly, the mine of Saelices el Chico, which was one of the most important of Western Europe, even though there are also other deposits that were not exploited like the ones at Alameda de Gardón, Villar de la Yegüa, Gallegos de Argañán, Casillas de Flores, Ituero de Azaba, San Felices de los Gallegos, Lumbrales and Sobradillo.

As a result of this uranium richness, “there is an important gamma radiation abnormality, especially in the region of Campo de Argañán”, points out Antonio García Sánchez. Gamma radiation are electromagnetic waves of high energy and, potentially, may be hazardous for health. The presence of uranium explains why this site has one of the highest levels of gamma radiation of the entire Iberian Peninsula. There are also waters with high levels of radioactivity; consequently, the use of deep wells to supply some villages in the watershed is prohibited.

Although this information may be known, the systematic and thorough study provided by this project, which is a part of the Operative Program of Cross-border Cooperation Spain-Portugal (POCTEP), financed with FEDER funds , has served to provide more concrete data than the ones registered by geographic information systems (SIG). “Even though the contamination is natural, it is important to know it and to check how it is distributed in the region, this way, at any moment, we may verify which risks exist at a certain spot”, comments María Jesús Sánchez.

The project began in 2011 and, although its end was predicted by 2013, there is the possibility of an extension until June 2014. The European University Miguel de Cervantes has studied the changes in the use of the soil; the Portuguese researchers, the contaminating elements behavior through geostatistical models; and IRNASA has started using different methodologies which evaluate the environmental impact and risks through water, soil and plant analysis.

Dissemination of data and experience

The watershed of river Águeda, tributary of Duero, is a small territory of 2.660 square kilometers located on the border of Spain and Portugal, though the methodology used in its analysis may be applicable to other places. “We came across a contamination of natural origin, but in Europe there are large watersheds contaminated by men’s actions, for example, between Germany and the Czech Republic”, points out Sara Sánchez González thinking about the utility of transferring this experience to other areas.

One of the objectives the three research centers have in common is spreading the results of the work, in a way that the book ‘Cuenca del río Águeda: un territorio para dos países’ may be thoroughly distributed among the administrations and people in charge, the ones who make management decisions and, in addition, many talks about environmental education for different groups have been organized.