Influence of Fe²⁺-catalysed iron oxide recrystallization on metal cycling

Recent work has indicated that iron (oxyhydr-)oxides are capable of structurally incorporating and releasing metals and nutrients as a result of Fe²⁺-induced iron oxide recrystallization. In the present paper, we briefly review the current literature examining the mechanisms by which iron oxides recrystallize and summarize how recrystallization affects metal incorporation and release. We also provide new experimental evidence for the Fe²⁺-induced release of structural manganese from manganese-doped goethite. Currently, the exact mechanism(s) for Fe²⁺-induced recrystallization remain elusive, although they are likely to be both oxide- and metal-dependent. We conclude by discussing some future research directions for Fe²⁺-catalysed iron oxide recrystallization.