The Source of Ions for Biomineralization in Foraminifera and Their Implications for Paleoceanographic Proxies

The global carbon cycle is strongly perturbed by fossil fuel burning leading to atmospheric CO2 increase. Climatic warming followed by polar ice melting and global sea level rise are predicted due to the greenhouse effect of increasing CO2 in the atmosphere (Houghton et al. 1995). The ocean plays a major role in neutralizing the excess CO2 because the amount of inorganic carbon available for exchange with the atmosphere in the ocean is approximately 50−60 times larger than in the atmosphere (e.g., Siegenthaler and Sarmiento 1993). The bulk of the atmospheric CO2 excess will eventually be neutralized by CaCO3 dissolution in the deep marine environment. This is, however, is a relatively slow process that operates on the time scale of ocean circulation (1000 yrs) and is therefore causing an accumulation of CO2 in the atmosphere. This phenomenon will result in potentially severe consequences to the well being of global ecological systems. Obviously the scientific attention of many biogeochemists is focused on processes controlling the response of the marine system to changes in atmospheric CO2 concentrations (e.g., Archer and Maier-Reimer 1994; Broecker 1997; Sigman and Boyle 2000; Berger 2002).