EUTROPHICATION IN HIROSHIMA BAY

Several researches for eutrophication in the northern Hiroshima Bay were carried out to investigate nutrient budgets in aquatic circulation processes, i.e. primary production, settling flux of particulate organic matter (POM) and the benthic remineralization. It became apparent from these investigations that primary production contributed to the organic pollution in the northern bay than land based organic loadings by a factor of 10, that approx. 70-80% of the POM originating in phytoplankton were easily remineralized into inorganic nutrients during the settling process in water, and that approx. 60% of nitrogen and 70% of phosphorus in POM settled on the sediments might be returned to the water colum by the release from benthic sediment.