Long–term performance evaluation of zero-valent iron amended permeable reactive barriers for groundwater remediation – A mechanistic approach

•Permeable reactive barriers can effectively clean up groundwater contamination.•Oxidation of zerovalent iron is a key driving force for mitigation of redox sensitive contaminants.•Dissolved oxygen and dissolved solids lead to decreased reactivity and altered water transport.•Effect of groundwater chemistry should be considered for future installations of PRBs.