MARINE CHEMISTRY 60, 33-47

Rising surface ocean dissolved inorganic carbon at the Hawaii Ocean Time-series site

Christopher D. Winn¹, Yuan-Hui Li², Fred T. Mackenzie², David M. Karl²

¹University of Hawaii at Hilo, Division of Natural Science, 200 W. Kawili Street, Hilo, HI 96720, USA

²School of Ocean and Earth Science and Technology, Department of Oceanography, University of Hawaii, Honolulu, HI, USA

(Received 6 March 1996; revised 15 November 1996; accepted 26 June 1997)

Surface ocean dissolved inorganic carbon (DIC) and titration alkalinity have been measured for 7 years as a part of the Hawaii Ocean Time-series (HOT) program. The time-series data set displays an interannual increase in the inventory of surface ocean DIC which we interpret as a response to increasing atmospheric carbon dioxide concentrations. The rate of increase in surface ocean DIC at the open ocean HOT site is approximately 1 µmol kg^-1 yr^-1 with a 95% confidence interval of 0.72 to 1.37 µmol kg^-1 yr^-1. This accumulation rate is consistent with the rate of increase predicted from the rise in boundary layer pCO₂.