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Oxidation of sulphides leads to the dissolution of metals, which are transported with water and accumulate at geochemical barriers. Such barriers can form in peat bogs. This paper gives an introduction into the long-term processes in Oostriku peat bog where high accumulations of heavy metals are observed. Peat and water samples are analysed for Fe, As and heavy metals (Cd, Cu, Mn, Ni, Pb and Zn) using different methods. A concept is based on the observations. Metals are leached by sulphide oxidation in the carbonate rocks upstream of the peat. The water feeds the peat from below. The metals are sorbed and precipitated in the peat. The sulphide oxidation is simulated to examine the origin and metal speciation in the water. The simulated solution is compared with the groundwater entering the peat. The results showed a fair agreement for the major constituents. There were considerable differences for species with low concentrations. 相似文献
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In this study, the retention of Ca and other metals (Pb, Cu, Fe, Zn and Mn) in the Oostriku peat bog (central Estonia) was modelled. Equilibrium sorption of metals on amorphous ferric oxyhydroxide and solid organic matter was simulated at steady-state. Ferric oxyhydroxide formation and possible precipitation of other metals (Mn, Pb and Cu) in the peat was also assessed. Evolution of metal sorption fronts along a peat profile over time was simulated with a dynamic model to test if metal–metal competition effects could cause Pb and Cu to sorb at higher amounts in the uppermost peat than in the lower peat, as observed in the field. The predicted sorbed amounts of metals were compared with those previously observed in the peat. In general, good agreement between both batch and dynamic model results and the independent observations at the Oostriku peat site was obtained. This suggests that the relatively simple model approach employed here might be generally useful for assessing other peat sites and similar applications. 相似文献
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