Abstract :
Distribution and forms of transition metals (Ti, Zn, Ni, Co, Mn, Fe, Cu, V and Cr) were investigated in oxidised, partly oxidised and reduced zones of sulphide-bearing fine-grained sediments located in the coastal areas of western Finland. Samples for the analysis and study of vertical distribution of elements were taken from each vertical 10 cm section in pits ranging in depth between 2 and 3 metres, while bulk samples for characterisation of species and forms of metals were taken from 3 zones in each pit: the acid sulphate soil (characterised by acid and oxidising conditions), transition zone (characterised by a steep pH gradient and partly oxidising conditions) and the reduced zone (pH >6). The former samples were digested in aqua regia (3:1:2 HCl:HNO3:H2O), while the latter were digested in aqua regia and hot concentrated acids (HClO4–HNO3–HCl–HF) and were subjected to extractions with acid ammonium acetate, H2O2 and acid ammonium oxalate. Each leachate was analysed for metals with ICP–AES.
