Ion exchange properties of manganese and iron minerals in oceanic micronodules

The results of experimental studies of ion exchange properties of manganese and iron minerals in micronodules (MN) from diverse bioproductive zones of the World Ocean are considered. It was found that the sorption behavior of these minerals is similar to that of ore minerals from ferromanganese nodules (FMN) and low-temperature hydrothermal crusts. The exchange complex of minerals in the MN includes the major (Na+, K+, Ca2+, Mg2+, and Mn2+) and the subordinate (Ni2+, Cu2+, Co2+, Pb2+, and others) cations. Reactivity of theses cations increases from Pb2+ and Co2+ to Na+ and Ca2+. Exchange capacity of MN minerals increases from the alkali to heavy metal cations. Capacity of iron and manganese minerals in the oceanic MN increases in the following series: goethite < goethite + birnessite < todorokite + asbolane-buserite + birnessite < asbolane-buserite + birnessite < birnessite + asbolane-buserite < birnessite + vernadite Fe-vernadite + Mn-feroxyhyte. The data obtained supplement the available information on the ion exchange properties of oceanic ferromanganese sediments and refine the role of sorption processes in the redistribution of metal cations at the bottom (ooze) water-sediment interface during the MN formation and growth.