Anomalously high concentration of Ni as sulphide phase in sediment and in water of a mountain catchment with serpentinite bedrock

Our results revealed a peculiar Ni speciation in the sediment samples, appointing to the presence as sulphide and differentiating from results of previous works usually indicating a main source bond to Fe and Mn oxides. These data probably revealed an important amount of sulphide minerals and were related to a relatively low weathering of glacial sediment. Moreover, water analysis showed a relatively high Ni concentration consistent with an enhanced dissolution. Enrichment due to atmospheric deposition is excluded by the temporal trend of Ni concentrations in water samples. Our results showed anomalies in Ni speciation and dissolution in water different from previous studies on the same bedrock type, raising new issues regarding the primary pedogenetical phase of serpentine soils and the dissolution of Ni in high mountain catchments.