Trace contaminant concentration affects mineral transformation and pollutant fate in hydroxide-weathered Hanford sediments

► Fate of Sr, Cs and I tracked during hydroxide-weathering of sediments. ► pCO2 and contaminant concentration affected mineral transformation. ► Sodalite/cancrinite formed at μM levels, chabazite at mM levels. ► Absence of CO2 resulted in calcite dissolution and strätlingite formation. ► Trace contaminant concentrations modified their own sequestration path.