Distributions and behavior of chromium species in natural waters―the chemical changes of chromium species in the Ibo River and Harima Nada

In order to understand the behavior of chromium at the confluence of the river and sea waters, the surface distributions of several chromium species have been investigated at the Ibo River with the influence of tannery effluents and Harima Nada (see Fig.1). The concentrations of particulate Cr, dissolved inorganic Cr (III) and dissolved organic Cr(III) gradually decreased from the upper stream in the Ibo River to the estuary, rapidly decreased from the estuary to O.5 km offing from the estuary and gradually decreased from O.5 km to 20 km offing from the estuary. These results indicate that the chromium species in the river waters rapidly diffuse into and are diluted with the sea water near the estuary. The concentrations of Cr(VI) in the sea waters at several sites fell within a narrow range (0.06-0.11 μg/l).