Study of complexation capacity and its relationship with some environmental variables in five reservoirs of the Tiete river system

The copper and cadmium complexation properties in natural sediment suspensions of reservoirs of the Tiete River were studied using the solid membrane copper and cadmium ion-selective electrodes. The complexation and the average conditional stability constants were determined under equilibrium conditions at pH=6.00 +/- 0.05 in a medium of 1.0 mol L-1 sodium nitrate, using the Scatchard method. The copper and cadmium electrodes presented Nernstian behavior from 1 X 10(-6) to 1 x 10(-1) mol L-1 of total metal concentration. Scatchard graphs suggest two classes of binding sites for both metals. A multivariate study was done to correlate the reservoirs and the variables: complexation properties, size, total organic carbon, volatile acid sulfide, E-H and pH.