Presented paper

IMWA2019 Students work

Tracing Solute Sources In Groundwater And Surface Waters In The Historical Yxsjöberg Cu-W-F Tailings Vicinities: Chemical And Isotopic Approaches

Salifu, Musah; Aiglesperger, Thomas; Alakangas, Lena
Luleå University of Technology, Sweden.

The abandoned Yxsjöberg Cu-W-F tailings, located in the south-central part of Sweden, are classified by the Swedish environmental agency (EPA) as one of Sweden’s most toxic mining legacy sites. Previous studies have shown that the surface waters downstream the tailings are impacted by effluents from the tailings. However, due to the complex mineralogy of the tailings, unravelling the geochemical controls on the solute chemistry based on the elemental concentrations have resulted in several unresolved questions related to multiple potential sources such as (i) mineral weathering, (ii) dilution and (iii) biological cycling.

Therefore, silica (δ30Si) and strontium (87Sr/86Sr) isotopes as well as the chemistry of groundwater in the Yxsjöberg Cu-W-F tailings and surface waters downstream of the tailings, were determined in this study to trace geochemical controls of the dissolved Si, Sr and other chemical constituents. Two groundwater and six surface water samples were sampled monthly from May to October, 2018.

87Sr/86Sr ratios in the groundwater ranged from 0.88957 to 1.07871 whereas that of the surface waters ranged from 0.72878 to 0.89991. δ30Si ranged from 0.477 to 2.790 ‰ in the groundwater samples. On the other hand, the surface water samples recorded δ30Si values between -0.239 and 0.184 ‰. The isotopic compositions of the groundwater samples in the tailings show contrasting results to that of the surface water samples.

Considering the fact that the surface waters have been reported to be impacted by the tailings, there is the need to decipher the processes influencing the observed trends in isotopic values. This would then provide the basis for the development of any future remediation or treatment strategies. Data interpretation is at an early stage and are therefore not presented here. However, preliminary results show interesting leads which would be discussed in the final manuscript to be submitted.