Inositol phosphates in aquatic systems

While there is a considerable body of research on the abundance and behavior of inositol hexakisphosphate in soils, much less is known regarding its behaviour in aquatic systems. The observed physico-chemical behaviour of this organic P species suggests that in marine and freshwaters, it should be complexed and precipitated by major ions such as calcium, magnesium, iron or aluminium, and thus immobilized in the sediments (de Groot and Golterman, 1993). Furthermore inositol hexakisphosphate is known to be un-amenable to hydrolysis by exocellular alkaline phosphatase or phosphodiesterase (Turner et al., 2002a), and it is therefore regarded as biologically unavailable to phytoplankton. These observations tend to reinforce the classical, and quite understandable view, that inositol hexakisphosphate exists in aquatic systems as an insoluble, refractory, immobile and biologically unavailable P species.