DETERMINATION OF IONIC-STRENGTH AND EQUILIBRIUM CONCENTRATIONS OF HEAVY-METALS BY THE ELECTRICAL-CONDUCTIVITY METHOD

A laboratory investigation of several types of heavy metal-soil soluti ons was conducted to evaluate the possibility of determining ionic str ength and equilibrium concentrations of heavy metals and exchangeable cations by means of the electrical conductivity method. The characteri stics of the heavy metal-soil interactions including retention of meta ls and release of exchangeable cations by the illitic soil were examin ed, and electrical conductivity and pH measurements of the heavy metal -soil solutions were performed. Test results revealed that direct dete rmination of equilibrium concentrations of certain ionic species could be realized by means of electrical conductivity measurements of soil suspensions. This laboratory technique is based on determining the rel ationship between the ionic strengths of the heavy metal-soil solution s and their electrical conductivity in order to derive the necessary c orrelations to estimate the equilibrium concentrations. The proposed t echnique is expected to aid in the direct calculation of equilibrium c oncentrations of metal ions and heavy metals from data collected durin g site investigation for remedial activity via electric conductivity o r soil resistivity techniques.