Estimation and simulation of metal mass transport in an old mining area

In a watershed with an old mine tailings deposit, mass transport of Cu, Zn and Cd was studied. An extensive sampling program and the use of the PULSE model for the simulation of water flow made it feasible to simulate and compare the dynamics of metal transport at different sites in the study area. Close to the tailings deposit, the weathering rate in the deposit had a large impact on the dynamics of the mass transport, and interannual variation in mass transport was considerably lower than the variation in runoff. Further downstream, the mass transport was almost exclusively determined by the water flow and, thus far unidentified, mechanisms maintained fairly constant metal concentrations in the stream water. the usefulness of the PULSE model for simulating metal concentrations may still be questioned. However, it is noteworthy that a hydrochemical model based on a fairly simple description of the mixing of water from different sources and a very simple pH dependence of the concentration of metals, at least semi-quantitatively, can reproduce the dynamics of metal concentrations and mass transport of metals.