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Carbonate Chemistry of the Weddell Sea
Concurrent pH, calcium, and total alkalinity data were obtained in the eastern Weddell Sea during the winter of 1981. These data represent the initial concentrations of calcium, alkalinity, and total CO2 in the most important source region of world ocean bottom waters at the time they were formed. For the first time, an evaluation of the variation of calcium and carbon cycles in the deep oceans referenced to the source water were made. The data were analyzed together with data from the literature, and the results indicated that: (1) the October pH values south of the Polar Front are indistinguishable from the November values, but the seasonal effect is large north of the front; (2) a large change in pH occurs at the ice edge; (3) partial pressure of CO2 in the Weddell Sea surface water is only slightly lower than the atmospheric value; (4) alkalinity does not show cross-ice- edge or seasonal variations, but the values seem to increase at a slower rate with decreasing temperature south of the Polar Front; (5) sea ice is relatively high in calcium and alkalinity concentrations; (6) mixing dominates the distribution of chemical properties; (7) pH is useful in identifying the sources of waters in the Weddell Sea, whereas calcium and alkalinity are not; (8) the surface water is deficient in CO2 from human activities because the pack ice blocks the air-sea exchange of gases; and (9) little excess CO2 can be found in the Antarctic Bottom Water. The situation may change, however, if the Weddell Sea ice coverage is reduced because of CO2-induced global warming. [The data set is available on tape (NDP-028) from the Carbon Dioxide Information Analysis Center at Oak Ridge National Laboratory.]
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