Anthropogenic CO2 in the ocean

Gruber, N., J. L. Sarmiento, and T. F. Stocker. 1996. An improved method for detecting anthropogenic CO2 in the oceans. Global Biogeochemical Cycles 10(4) 809-837. 

Vertical column inventory of anthropogenic CO2 in the ocean (mol/m ). High inventories are associated with deepwater formation in the North Atlantic and intermediate and mode water formation between 30°S and 50°S. Total inventory of shaded regions is 106 17PgC. Source-. From Sabine, C. L., et al. (2004). Science 305, 367-371. (See companion website for color version.)... 

The uptake of anthropogenic CO2 by the ocean is a crucial process for the carbon cycle, resulting in changes of the 5 C-value of dissolved oceanic bicarbonate (Quay et al. 1992 Bacastow et al. 1996 Gruber 1998 Gruber et al. 1999 Sonnerup et al. 1999). Quay et al. (1992) first demonstrated that the 5 C-value of dissolved bicarbonate in the surface waters of the Pacific has decreased by about 0.4%c between 1970 and 1990. If this number is valid for the ocean as a whole, it would allow a quantitative estimate for the net sink of anthropogenically produced CO2. Recent accounts estimate that the Earth s ocean has absorbed around 50% of the CO2 emitted over the industrial period (Mikaloff-Fletcher et al. 2006). 

Gruber, N. 1998. Anthropogenic CO2 in the Atlantic Ocean. Global Biogeochemical Cycles 12(1) 165-191. 

One of the major environmental issues of our time is the impact of anthropogenically generated CO2 on the environment (see Chapter 9 for discussion). The major processes associated with fossil fuel CO2 in the oceans are the uptake of fossil fuel CO2 by the upper ocean, mixing and transport within the ocean, and reaction with calcium carbonate in sediments. In addition, biologic productivity may be influenced by increased Pc02 values- The two major reactions for uptake of CO2 by the oceans, beyond those that would occur for a chemically unreactive gas, are in a simple form ... 

There have been many calls to sequester anthropogenic CO2 in the deep ocean by stimulating... 

In the second case (Figure 10.34B), the excess carbon is stored in the ocean, either in the water column or in sediments, and the CO2 evasion flux is maintained at the geologic rate. In this case, the oceanic reservoir gains 59.2 x 1012 moles C y1, an increase in storage capacity of 11% of the anthropogenic flux of carbon to the atmosphere. Much of this increase takes place in the nearshore realm, although potential transport of DOC, POC, and DIC to the open ocean would also increase the loading of this part of the ocean. 

Kortzinger A. and Quay P. (2003) Relationdiip between anthropogenic CO2 and the Seuss effect in the North Atlantic Ocean. Global Biogeochem. Cycles 17(1), 1005. 

Figure 4 Vertical profiles of total dissolved inorganic carbon (TIC) in the ocean. Curve A corresponds to a theoretical profile that would have been obtained prior to the Industrial Revolution with an atmospheric CO2 concentration of 280 ixmol mol The curve is derived from the solubility coefficients for CO2 in seawater, using a typical thermal and salinity profile from the central Pacific Ocean, and assumes that when surface water cools and sinks to become deep water it has equilibrated with atmospheric CO2. Curve B corresponds to the same calculated solubility profile of TIC, but in the year 1995, with an atmospheric CO2 concentration of 360 xmol moPk The difference between these two curves is the integrated oceanic uptake of CO2 from anthropogenic emissions since the beginning of the Industrial Revolution, with the assumption that biological processes have been in steady state (and hence have not materially affected the net influx of CO2). Curve C is a representative profile of measured TIC from the central Pacific Ocean. The difference between curve C and B is the contribution of biological processes to the uptake of CO2 in the steady state (i.e. the contribution of the biological pump to the TIC pool.) (courtesy of Doug Wallace and the World Ocean Circulation Experiment).

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