Elements speciation ocean table

Table 2 The residence time and speciation of some elements in the ocean...

Certainly, CO2 evolved during late diagenesis must ultimately return to the atmosphere/ocean. It also seems clear that transport of major components such as silicon and potassium between sandstones and shales at a scale of a few meters is required and can perhaps be accomplished by diffusion (Thyne et ai, 2001). New data, especially for shales, must be obtained before simultaneous quantitative balances can be proposed for the reactions in Table 1. The speciation of aluminum in pore fluids, the initial and final quantities of the reactants and products in both sandstones and shales, and the precise volumes of sandstones and shales in the sequences in question are key data needed to ascertain the scale of mobihty for the major elements in late diagenesis. Our abihty to answer basic questions about the rock cycle falls short, in large part, for lack of information about the major mineral components of shale, the most common type of sedimentary rock. 

Table 1 Summary of the hydroxide speciation, concentrations, and residence times for the refractory elements in the oceans...

Mercury is a unique metal. Its oceanic background concentration (Hgx) is very low (< 1 ng/L see also Table 12-1). The risks of rapid changes in speciation, losses and contamination of samples by contact with laboratory air, materials and reagents are high. In contrast to other trace elements, seawater reference materials certified for mercury concentration are not yet available. The quality assurance with regard to accuracy of data is further hampered by the fact that most laboratories, due to the lack of alternative methods, follow almost the same analytical approach. 

Redox potential (oxidation-reduction) is considered a master variable with respect to controls on the concentration and speciation of many trace elements in natural waters (Stumm and Morgan 1981). Shifts between oxic, suboxic and anoxic conditions represent one of nature s most dramatic chemical variations. The response of lanthanides to variations in redox conditions has been studied in many of the world s classic anoxic and suboxic basins. These include (1) the Black Sea (German et al. 1991, Schijf et al. 1991, 1994, Schijf and De Baar 1995), (2) Saanich Inlet (Canada) (German and Elderfield 1989), (3) Chesapeake Bay (Sholkovitz and Elderfield 1988, Sholkovitz et al. 1992), (4) the Cariaco Trench (De Baar et al. 1988), (5) the Mediterranean Sea (Schijf et al. 1995) and (6) the northwest Indian Ocean (German and Elderfield 1990). The latter two regions are located on ocean shelves while the first three basins are estuarine and coastal. Data from the papers cited above are compiled in table A12. 

---