Tsunogai et al.'s (1999)[1] original work focused on the East China Sea, and the observation that, averaged over the year, its surface waters represented a sink for carbon dioxide.
One caveat to this calculation is that the original work was concerned with the hydrography of the East China Sea, where cooling plays the dominant role in the formation of dense shelf water, and that this mechanism may not apply in other regions.
The strong sink of CO2 at temperate latitudes reported by Tsunogai et al. (1999)[1] was later confirmed in the Gulf of Biscay,[6] the Middle Atlantic Bight[7] and the North Sea.
[9] Recently, work[10][11] has compiled and scaled available data on CO2 fluxes in coastal environments, and shown that globally marginal seas act as a significant CO2 sink (-1.6 mol C m−2 y−1; -0.45 Gt C y−1) in agreement with previous estimates.
An interesting application of this work has been examining the impact of sea level rise over the last de-glacial transition on the global carbon cycle.