Monitoring the construction of wells, avoid over-exploiting cold groundwater close to hot groundwater, and controlling mineral water extraction. These are the recommendations from the Polytechnic University of Catalonia and the University of Barcelona, after analysing the contamination of La Selva geothermal system, above all by arsenic pollution. In this region, which is known for its spa resorts and bottling plants, as well as in other Catalan coastal mountain ranges, uranium levels higher than what is recommended by the WHO have been detected.
The groundwater in La Selva (Girona, Spain) area show high levels of arsenic, antimony and other polluting elements. The area's geothermal system, where hot and cold groundwater flow naturally, are the cause of this situation, according to a study that researchers from the Polytechnic University of Catalonia (UPC) and the University of Barcelona (UB) have published in the journal Geothermics.
"The system works by refilling meteoric waters that penetrate the earth in high areas, move underground and reach an unknown thermal hot spot, where they heat up and acquire CO2, and probably metals as well "Andrs Navarro, a lecturer at UPC and co-author of the project explained to SINC. "Afterwards the water leaches out (dissolve) the host rocks and flows out from the upwellings".
In this process the waters naturally pick up pollutants. Consequently, the researchers have found high volumes of arsenic, silver, lead, antimony, zinc and other metals in the hydrothermal deposits, especially in the area of Caldes de Malavella (Girona), an area famous for its spa resorts and mineral water bottling companies.
The results show that groundwater in some areas has arsenic levels of up to 0.069 mg/l, when the legal limit in Spain and the rest of the European Union was 0.01 mg/l in water for human consumption.
"Fortunately, a few years ago a legislation for this was created
FECYT - Spanish Foundation for Science and Technology