Forms of Iron and Manganese in Lake Erie Waters

Abstract

About 95% of the iron observed in the lake water is bound to inorganic particles and is present in the water because of sediment resuspension. Contrary to popular belief, the upwelling of interstitial waters charged with ferrous iron does not appear to play an important part in the regeneration of iron from Lake Erie sediments except when anoxic conditions exist at the sediment–water interface. By contrast, manganese is usually found in the overlying water as a result of the release of interstitial water containing dissolved manganese. This precipitates in oxygenated water so that most of the manganese present in the water is found in the particulate form. However, the released manganese will remain soluble if the oxygen saturation is less than 50%. In general, it was found that both the iron and manganese were in the particulate or soluble form in accordance with the geochemical solubility rules.