Abstract
In this work we present the results of a methodological research on the chemical speciation of heavy metals found in surface waters of an area polluted by mining activities (in the Western Carpathians). The surface water samples were collected in two seasons (summer and fall). Each time were performed in situ physical-chemical measurements (pH, Eh, conductivity, temperature) and analytical determination of total concentrations of some metals (manganese, copper, zinc, iron, cadmium) and anions (SO<sub>4</sub><sup>2-</sup>, Cl<sup>-</sup>, PO<sub>4</sub><sup>3-</sup>, NO<sub>3</sub><sup>-</sup>). Analyze of chemical speciation of these metals was made using the PHREEQC program which allowed us to determine the distribution of studied elements.
The concordance of the results obtained with this program with thermodynamic predictions arising from potential - pH equilibrium diagrams - Pourbaix type justify the compatibility between the program calculation and experimental data.