The recovery process determination of hypoxia based on long-term observation at northwestern Tokyo Bay, Japan

Abstract

To determine the recovery process of hypoxia of bottom water at northwestern Tokyo Bay, Japan, the seawater characteristics, climate condition and flow regime have been monitored for three years. Following results were obtained that 1) the recovery process of hypoxia could be triggered by the intrusion of high density and oxygen rich bottom water from the bay mouth, 2)the typical velocity of those water mass was estimated as 2.7(±1.2) km/day from the change of the isopycnic line, and 3) associated increment of the density and oxygen recovery were observed with short term tidal motion. Thus, the recovery process of the hypoxia of bottom water could be influenced and triggered by the wind and the flow regime of concerned area.