ORIGIN AND DISTRIBUTION OF INOSITOL HEXAPHOSPHATE IN ESTUARINE AND COASTAL SEDIMENTS

In order to clarify the origin and the fate of inositol hexaphosphate (IP6) in coastal sediments from Tokyo Bay, we determined IP6 in severa l potential source materials, such as plankton, soil, riverine, and es tuarine samples. IP6 was not found in zoo- and phytoplankton samples, thus eliminating these as a source to the sediments. Soils collected f rom the catchment areas of major rivers flowing into the bay contained high concentrations of IP6 (0.25-5.65 mu mol P g(-1)). Samples of sus pended solids and estuarine sediments from the rivers also had signifi cant amounts of IP6. The distribution pattern of IP6 in Tokyo Bay sedi ments exhibited relatively high concentrations in the estuarine areas, decreasing gradually toward the mouth of the bay. The IP6 in coastal sediments was composed of three isomers in the same order of abundance as those found in the terrestrial and riverine samples: myo- >> scyll o- > chiro-. From these results, IP6 in Tokyo Bay sediments was ascrib ed to soils transported by rivers from land into the bay. The IP6 conc entration ranged from 0.01 to 0.10 mu mol P g(-1) in surface sediments (0-2.5 cm), accounting for < 1.2% of the total organic P; it was comp letely decomposed in the subsurface. Consequently, this compound is qu ite ephemeral in coastal marine environments.