FCO(2) DYNAMICS IN THE ATLANTIC, SOUTH-PACIFIC AND SOUTH INDIAN OCEANS

Subsurface fugacities of CO2 (f(CO2)(20)) can be used in combination w ith total dissolved inorganic carbon (DIC) to precisely calculate tota l alkalinity. Thus it can be used to determine dissolution of calcium carbonate (hard tissue) and remineralization of organic material (soft tissue), to quantify saturation constants of calcite and aragonite in seawater, and to characterize water masses. f(CO2)(20) is a good trac er of biological transformation since it is thermodynamically related to the other inorganic carbon system parameters and it has a dynamic r ange from 200 to 2000 mu atm in the world's ocean. Precision of f(CO2) measurements is 0.3% and the values are well calibrated using compres sed gas reference standards. Increases of f(CO2)(20) are observed as t he water masses age during movement from the Atlantic to the Indian an d South Pacific oceans. As an example of the determination of the rati o of soft tissue remineralization to hard tissue dissolution from f(CO 2)(20) and DIC, the trends along the 27.2 isopycnal for the subtropica l gyres of the three basins are investigated. Little CaCO3 dissolves a long this isopycnal in the Atlantic and the South Pacific while the so ft tissue remineralization to hard tissue dissolution ratio in Indian Ocean is 4.5:1. The difference in this ratio along the 27.2 isopycnal appears to be a combination of the calcite and aragonite saturation le vels and the supply of aragonite tests. (C) 1998 Elsevier Science B.V.