Impact of potash mining in streams: the Llobregat basin (northeast Spain) as a case study

Abstract

Potash mining is significantly increasing the salt concentration of rivers and streams due to lixiviates coming from the mine tailings. In the present study, we have focused on the middle Llobregat basin (northeast Spain), where an important potash mining activity exists from the beginning of the XX century. Up to 50 million tonnes of saline waste have been disposed in the area, mainly composed of sodium chloride. We assessed the ecological status of streams adjacent to the mines by studying different physicochemical and hydromorphological variables, as well as aquatic macroinvertebrates. We found extraordinary high values of salinity in the studied streams, reaching conductivities up to 132.4 mS/cm. Salt-polluted streams were characterized by a deterioration of the riparian vegetation and the fluvial habitat. Both macroinvertebrate richness and abundance decreased with increasing salinity. In the most polluted stream only two families of macroinvertebrates were found: Ephydridae and Ceratopogonidae. According to the biotic indices IBMWP and IMMi-T, none of the sites met the requirements of the Water Framework Directive (WFD; i.e., good ecological status). Overall, we can conclude that potash-mining activities have the potential to cause severe ecological damage to their surrounding streams. This is mainly related to an inadequate management of the mine tailings, leading to highly saline runoff and percolates entering surface waters. Thus, we urge water managers and policy makers to take action to prevent, detect and remediate salt pollution of rivers and streams in potash mining areas.

Microbial and macroinvertebrate communities, but not leaf decomposition, change along a mining‐induced salinity gradient

“…Our results do not support this hypothesis but this could be because the salinity gradient studied here was relatively moderate in comparison to other systems (e.g. Kefford et al., ), including other mining‐influenced steams (Fritz et al., ; Ladrera, Caņedo‐Argüelles, & Prat, ). We expect that macroinvertebrate replacement occurs at low to moderate increases in salinity above natural levels, as shown here, but nestedness is likely to occur at higher salinity levels.…”

“…Indeed, diverse bacterial communities exist in non-saline and hypersaline environments (Lozupone & Knight, 2007) (Fritz et al, 2010;Ladrera, Caņedo-Argüelles, & Prat, 2017). We expect that macroinvertebrate replacement occurs at low to moderate increases in salinity above natural levels, as shown here, but nestedness is likely to occur at higher salinity levels.…”

Dangerous assemblages: Salts, trihalomethanes and endocrine disruptors in the water palimpsest of the Llobregat River, Catalonia

“…According to the plans of reduction and re-use announced by the current owner of the mines, waste will not be eliminated before 2065. The dystopic futures brought about by the salinization of Llobregat waters may have not come true, but the landscape legacies of potash mining continue conditioning river biota and invertebrate communities (Cañedo-Argüelles et al, 2012Ladrera et al, 2017) as well as the technology required for human water supply.…”

“…Salt and other inorganic pollutants from mining have been traditionally difficult to remove in treatments at water purification plants (Fernández-Turiel et al, 2000). River microorganisms and invertebrates can also be significantly altered by the salinity caused by mine tailings, promoting the dominance of certain organisms and changing the composition of the invertebrate communities (Cañedo-Argüelles et al, 2012Ladrera et al, 2017).…”

Halophilic Algal Communities in Biological Soil Crusts Isolated From Potash Tailings Pile Areas

“…As a consequence, the load of salt ions in water bodies significantly affects the biotic communities, most often described as a decline in aquatic macroinvertebrate and fish diversity (Braukmann and Böhme, 2011;Arle and Wagner, 2013;Ladrera et al, 2017). Terrestrial habitats are also affected by potash tailings piles, and many studies have described the diversity of halophilic fauna and especially flora that replaced native species.…”