GEOCHEMISTRY OF CARBON-DIOXIDE IN SEAWATER AT THE HAWAII OCEAN TIME-SERIES STATION, ALOHA

This paper examines the fundamental biological and physical processes controlling the distribution of the inorganic carbon species throughou t the water column at the Hawaii Ocean Time series station, ALOHA. Pro files of alkalinity and calcium are strongly influenced by the distrib ution and movement of the six water masses at this location. The semic onservative behavior of these parameters can be useful in identifying water masses. The dissolution of carbonate particles, however, contrib utes up to 21% (49 mu mol C kg(-1)) of the dissolved inorganic carbon added to the intermediate waters between the time the waters enter the Pacific and the time they reach Station ALOHA. A sharp increase in ca rbonate-derived carbon observed between 800 and 2200 m is due to the d issolution of the more soluble forms of carbonate such as aragonite. T he distribution of TCO2 and pH at this site are significantly affected by biological processes as indicated by the apparent nonlinear mixing curves between water masses, the similarity of the measured ratios of C:N and C:P to the Redfield ratios in the upper 700 m of the water co lumn, and the results of a carbon system model. The nonconservative na ture of these properties demonstrates that both physical and biologica l factors must be considered when evaluating temporal variability. The carbon system evaluation techniques presented here are similar to tho se used on several previous trans-Pacific cruises allowing the results from this station to be compared to the results of other cruises in t his area.