The application of pHstat leaching tests to assess the pH-dependent release of trace metals from soils, sediments and waste materials

A multidisciplinary approach combining mineralogical analysis (X-ray diffraction) with chemical analysis, pHstat leaching tests and geochemical modelling (MINTEQA2) can provide information on the solid-phase speciation and reactivity of heavy metals in soils, sediments and waste materials. Besides the influence of pH on heavy metal leaching behaviour, additional information on heavy metal leachability and retention by the solid matrix was obtained from the kinetics of metal release during a pHstat test.