Temporal variation of the partial pressure of CO sub(2) in surface seawater of Iyo Nada in the Seto Inland Sea, Japan

• Published in: Journal of oceanography 1995-01, Vol.51 (6), p.681-697
• Main Authors: Kumamoto, Yu-Ichiro, Fujiwara, Kitao, Tsubota, Hiroyuki
• Format: Article
• Language: English
• Subjects: Marine
• ISSN: 0916-8370

The temporal variation of the partial pressure of carbon dioxide ( P sub(co) sub(2))in surface seawater of Iyo Nada in the western Seto Inland Sea was measured by infrared absorption of carbon dioxide (CO sub(2)) in air equilibrated with seawater. The variation of P sub(co) sub(2)) from January to late May in 1994 was relatively small (from 270 to 340 mu atm). On the contrary, the P sub(co) sub(2) measured in September l993 ranged from 200 to 450 mu atm. It seems that the relative high P sub(co) sub(2) observed in the north and the south of Iyo Nada in September were caused by destruction of a stratification owing to tidal currents at straits between Hiroshima Bay and Iyo Nada and Hayasui Straits, respectively. The low P sub(co) sub(2) observed in the central Iyo Nada in September was ascribed to a tidal front where high concentrations of chlorophyll-a and a relation between P sub(co) sub(2) and chlorophyll-a in negative sense were found. Except the observation in the north of Iyo Nada in September, the P sub(co) sub(2) in the surface seawater of Iyo Nada were lower than the atmospheric P sub(co) sub(2) (about 367 mu atm). The results obtained by this work and Kimoto et al. (1993) lead to the conclusion that Iyo Nada acts as a sink of the atmospheric CO sub(2) on the average.