Manganese speciation in dilute waters of the Precambrian shield, Canada

In contrast to its physical state in some geographical areas, manganese in waters draining the Precambrian shield in Canada is mostly non-particulate. Using a differential pulse anodic stripping voltammetry speciation technique, we demonstrate a trend from ionic Mn(II) dominance at low pH to an increasing proportion of colloidal manganese oxyhydroxides at pH 5.5 in non-dystrophic waters. The relationship of Mn(II) with pH in the oxic, non-dystrophic samples is consistent with a Hausmannite or Feitknechtite controlling phase.