Shallow coastal waters (SCWs) have attracted wide attention in recent years due to their strong carbon sequestration capacity. However, the complex carbon dioxide (CO2) dynamics in the water column makes it difficult to estimate the air–water CO2 fluxes (FCO2) accurately. We developed a numerical model of CO2 dynamics in water based on field measurements for a typical stratified semi-enclosed shallow bay: the Yatsushiro Sea, Japan. The developed model showed an excellent ability to reproduce the stratification and CO2 dynamics of the Yatsushiro Sea. Through numerical model simulations, we analyzed the annual CO2 dynamics in the Yatsushiro Sea in 2018. The results show that the effect of stratification on the CO2 dynamics in seawater varies greatly depending on the distance from the estuary and the period. In the estuarine region, stratification manifests itself throughout the year by promoting the maintenance of a high partial pressure of CO2 (pCO2) in surface waters, resulting in surface pCO2 being higher than atmospheric pCO2 for up to 40 days during the flood period (average surface pCO2 of 539.94 µatm). In contrast, in areas farther from the estuary, stratification mainly acts to promote the maintenance of high pCO2 in surface waters during periods of high freshwater influence. Then changes to a lower surface pCO2 before the freshwater influence leads towards complete dissipation. Finally, we estimated the FCO2 of the Yatsushiro Sea in 2018, and the results showed that the Yatsushiro Sea was a sink area for atmospheric CO2 in 2018 (−1.70 mmol/m2/day).

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3 正会員 神戸大学大学院教授 工学研究科市民工学専攻(〒657-8501 神戸市灘区六甲台町1-1) 4 正会員 北見工業大学准教授 工学部社会環境系(〒090-8507 北海道北見市公園町165番地)

We examined the speed of the blood flow in the vena femoralis to verify the effects of an elastic stocking, intermittent air pressure and active ankle movement on the prevention of deep vein thrombosis. [Subjects] The subjects were 16 healthy men who had no history of vascular lesion. [Method] We performed a comparative study on the speed of blood flow speed in the vena femoralis among five conditions: at rest, wearing elastic stockings, intermittent air pressure, and active ankle movements of 40 or 80 times a minute. [Results] The blood flow speed was 30.7  5.2 cm/s at rest, 29.1  6.6 cm/s wearing the elastic stocking, 50.4  19.3 cm/s with intermittent air pressure, and 50.7  21.7 cm/s and 59.3  38.4 cm/s for active ankle movements of 40 and 80 times a minute, respectively. Significant differences were found between volitional movement at 80 times a minute and wearing a stocking and at rest. [Conclusion] Active movement of 80 times a minute increased the blood flow speed, suggesting that changes are not seen with external stimuli or slow muscle pumping.

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