Four soil samples were collected in areas adjacent (sanitary zone) to the Głogów Copper Plant (Poland). They were mostly acidic (pH 4.55 - 4.71) and the total varied widely in their total copper content from 17.03 to 44.07 cM_c/kg. The basic copper fractions were determined according to McLaren and Crawford sequential extraction method. Copper of the solution (intensity) expressed as the equilibrium activity ratio, AR_o^Cu when Cu was neither gained nor lost (that is DCu_o = 0) as well as labile Cu (L_Cu) was related to the solid soil phase (quantity) considered as the buffering capacity (BC^Cu) of the given soils were calculated. The Q/I parameters were estimated at two ionic strengths: 0.005 and 0.010M CaCl₂. It was found that all parameters depended on the ionic strength and higher values were obtained at 0.010M CaCl₂. An adverse case occurred for the energy of replacement of calcium by copper (DF). Soil properties primarily influenced the magnitude of the Q/I parameters and secondly the high levels of exchangeable and labile soil copper. The low affinity of these soils for copper estimated by the Gapon selectivity coefficients (K_G) supported this assumption.