The inorganic chemical species in Maresh and Luda Yana rivers affected
by the Cu-Mo Asarel-Medet mine, Bulgaria were determined during a
low-flow and a high-flow period. The mining activities, the weathering
and the oxidation processes strongly influenced the physicochemical
processes in the whole water system. The main pollution source was a
small lake receiving the acid effluents of the mining activities. High
levels of SO42-, Cu, Mg, Al, Mn and Fe were determined at the mining
polluted and affected stations. Cu2+ and CuCO30 species (1: 1) were
present in the reference waters and Cu2+ and CuSO40 species (1: 1) in
the polluted and affected waters; Cu2+ species was dominating
downstream. Me2+ followed by MeSO40 (Me = Mn, Zn, Cd and Pb), PbCO30 and
PbHCO3+ species as well as Fe(OH)(2)(+), Al(OH)(4)(-), Al(OH)(2)(+),
Al(OH)(3)(0) were prevailing in the system. MeSO4+ ans Me(SO4)(2)(-) (Me
= Fe, Al), Me(SO4)(2)(2-) (Me = Zn, Cd and Pb), Me(SO4)(3)(4-) (Me = Zn,
Cd) and Cd(SO4)(4)(6-) species appeared in polluted and affected
waters.The trace element concentrations decreased downstream due to
dilution, sorption processes and precipitation, but the percentage of
free metal species, which are more toxic, increased. An exception was
iron and aluminum of which the dominant hydroxy colloidal and sulphate
species were easily incorporated into the suspended phase
