Influence of hydrochemical parameters on the mobility and redistribution of metals from a mine waste deposit

The aim of the research presented in this thesis has been to combine theoretical and empirical methods to describe chemical attenuation of trace metals (i.e. Al, Cd, Cu, Fe, Mn, Pb and Zn) in a polluted watershed. It was possible to elucidate the major mechanisms by using the naturalvariations of chemical composition of the system. Both equilibrium and kinetic conditions are of importance for the redistribution of metals. Adsorption to suspended solids is the major mechanism of apparent solubility control in the undersaturated state. The process is highly related to pH conditions through formation of different soluble species and coatings of inorganic precipitates as well as adsorption of organic macromolecules. Adsorption to bottom sediments is limited under pH conditions below hydrolysis of the respective elements. The distribution of solid metal species is correlated to those in the suspended phase. Iron and manganese oxides act as adsorbents under oxidizing conditions while aluminium hydroxides become more important under reducing conditions. Diffusion controlled metal migration in a non-flowing aqueous phase, e.g. clay matrix, is related to their chemical speciation. Microbial activity impacts the distribution of the considered elements in the soil environment. Their mobility is under both aerobic and anaerobic conditions correlated to microbial populations, up to some critical biomasses.