Adsorption of trace elements on pyrite surfaces in sulfidic mine tailings from Kristineberg (Sweden) a few years after remediation

Laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) has been used to determine the elemental composition of the surface and interior layers of pyrite grains from the mine tailings from Kristineberg (northern Sweden) in order to determine concentration gradients between these two layers. The pyrite grains were collected from oxidized and unoxidized zones within the tailings. The aim of this study was to assess the role of pyrite surfaces as sites for the attenuation of solutes from the mine-tailings porewater. The normalized intensities of Cu, Zn, Ag, Sb, Ce, Pb and Bi are highest at the surface of each grain (within the surface layer drilled by the LA) and decrease towards the interior. The surface adsorption of Cu, Zn and Pb is more pronounced within the unoxidized than within the oxidized zone of the tailings. Copper exhibits a distinct concentration peak at the surface of the pyrite grains below the pre-remediation oxidation front. Silver, Sb, Bi, As and Au are preferably adsorbed within the uppermost layer of the oxidized zone in the tailings, where the pH is as high as 6.2. The conversion of intensity signals of the elements to concentration values in ppm was accomplished using an external calibration against an in-house pyrite standard.