Biogeochemical transformations of Fe and Mn in oxic groundwater and well water environments

Abstract

Abstract This review presents an overview of the oxidation and precipitation of dissolved Fe(II) and Mn(II) in groundwater when exposed to surface conditions. In water wells, these transformations may eventually result in biofouling problems and deterioration of water quality. Fe(II)‐oxidation products include poorly‐ordered Fe(III)‐oxides such as ferrihydrite which may be converted via solution to Fe(III)‐oxyhydroxides (e.g., goethite) with time. Among Mn‐oxides, a typical oxidation product is birnessite which is structurally analogous to poorly‐ordered ferrihydrite. Bacteria implicated in Fe‐ or Mn‐oxidation in neutral‐pH environments include Gallionella, Sphaerotilus, Leptothrix, Metallogenium, Pedomicrobium spp., and magnetotactic bacteria. Very little information is available on the genera Crenothrix, Clonothrix, Toxothrix, and Siderocapsa. This review focuses on the stalked and sheathed bacteria Gallionella, Leptothrix, and Sphaerotilus.