The project aims to generate new scientific knowledge on the phenomenon of the release and precipitation of potentially toxic chemical compounds related to acid drainage.

The Universitat Autònoma de Barcelona has completed the project ‘Acidification of high mountain water bodies and its relationship with climate change, toxicity and implications for biodiversity’. An initiative that has had the support of the Biodiversity Foundation of the Ministry for Ecological Transition within the framework of its call for grants.

The AMiCC project has aimed to study the processes that cause the acidification of water bodies and the precipitation of whitish compounds that have been observed in the protected areas of the high mountains of the Pyrenees, in the last decade. To this end, study areas have been selected in the natural parks of Posets-Maladeta, Alt Pirineu and Capçaleres del Ter i del Freser.

For a year, cartography, photointerpretation, sampling and hydrochemical and bioindicator analysis have been carried out; determinations of stable and unstable isotopes, and geophysical exploration of affected water bodies.

The results obtained indicate that the observed phenomenon is related to natural acid drainage processes that originate in rock massifs rich in sulfide mineralizations; essentially in the areas where these massifs are affected by large landslides and covered with detrital deposits such as rock glaciers, evidencing a marked geomorphological control. Acid drainages cause the acidification of surface and groundwater bodies, as well as their enrichment in potentially toxic metals and metalloids.

The implications for biodiversity of affected habitats are clear. The communities in acidified waters are poorer in terms of species and biodiversity, with some species being replaced by more acidophilic ones. The implications for health are not so obvious, although it cannot be ruled out that, if the process evolves, they could affect the water resources of some populations. The established temporal patterns allow us to affirm that natural acid drainages have already been occurring in the recent geological past. However, these drainages have intensified in the last decade, reflecting a marked climate control related to low rainfall and especially to temperature. Given that climate forecasts point to global warming, the effects of natural acid drainages could worsen and become widespread in the Pyrenees in the future, so it is considered important to continue monitoring their evolution in the coming years.

The analysis and monitoring of these processes can be an early indicator of the effects of global warming in the mountain areas of the Mediterranean region. The results obtained could also be easily replicated and integrated with other similar research carried out in other mountain areas at higher latitudes (such as in the Alps or Scandinavian Mountains), which could contribute to obtaining valuable models at the regional scale.