Distribution and Seasonal Variation of Phosphorus in Tokyo Bay

概要

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Phosphorus dynamics in Tokyo Bay waters were investigated along with other oceanographic variables. Seasonal variations of dissolved inorganic phosphorus (DIP) and particulate phosphorus (PP) are inversely correlated with each other, and reflect variation in biological activity. A high concentration of PP in summer surface waters is caused by high primary production. The PP settled in the deeper layer is decomposed, and orthophosphate is regenerated within the water column andin sediments. Even during summer stratification period, the regenerated orthophosphate is occasionally advected upward by wind-induced water mixing and contributes to phytoplankton growth in the upper layer. Some dissolved organic phosphorus is produced <I>in situ</I> from PP, but it may be rapidly decomposed in the water column. The ratios of C: chlorophyll <I>a</I> and C: N in particulate matter suggest that phytoplankton in the summer surface waters of Tokyo Bay are limited neither by nitrogen nor by phosphorus. The P: N ratio in particulate matter varies substantially but it is positively correlated with the ambient concentration of DIP. Phytoplankton take up and store phosphorus within their cells when ambient DIP exceeds their demand. An abundance of total phosphorus in the summer water column can be attributed to increased discharge of river waters, although enhanced release of orthophosphate from anoxic sediments cannot be discounted.
日本海洋学会の論文