459
Processes in the Oceans
The changes in total alkalinity (TA) relative to H 2 S are given by
ΔTA/­ ΔH 2 S = (106 + 16 – 2)/53 = 2.3
The changes between TA and TCO 2 (total carbon dioxide) are given by
ΔTA/­ ΔTCO 2 = (106 + 16 – 2)/106 = 1.13
These relationships allow one to examine the chemistry of anoxic basins. In the next sections, the distribution of various chemicals is examined for some anoxic basins.
10.3.1 The black Sea
The Black Sea is the largest and most studied anoxic basin (Figure 10.45). The present
anoxic conditions began about 1500 to 2000 years after the influx of saline Mediterranean
seawater into the basin. It is an estuarine basin with an area of 413,500 km 2 , where precipitation and river runoff exceed evaporation. There is a net outflow (12,600 m 3 s –1 ) of
low- salinity water compared to the inflow (6100 m 3 s –1 ) from the Mediterranean. This
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Mixing
Mixing + removal
Mixing
Mixing + removal
Mixing
Mixing + removal
Mixing
Mixing + removal
Figure 10.41
Concentrations of Cu, Zn, Co, and Pb in vent particles as a function of Fe.