Atlantic Ocean oxygen level

Typical vertical saturation profiles for the North Atlantic, North Pacific, and Central Indian oceans are presented in Figure 4.10. The profiles in the Atlantic and Indian oceans are similar in shape, but Indian Ocean waters at these GEOSECS sites are definitely more undersaturated than the Atlantic Ocean. The saturation profile in the Pacific Ocean is complex. The water column between 1 and 4 km depth is close to equilibrium with calcite. This finding is primarily the result of a broad oxygen minimum-C02 maximum in mid-water and makes choosing the saturation depth (SD) where Oc = 1 difficult (the saturation depth is also often referred to as the saturation level SL). 

The level of soluble thallium present in the sea (e.g. Pacific Ocean, Atlantic Ocean, Irish Sea, Australian Coast) is between 9 and 16 ng/L (Matthews and Riley, 1970). This is remarkably lower than in fresh waters. In natural sea water (pH 8.1), the oxygen content is sufficient to oxidize Tl(l) to Tl(lll). because formation of chloro-complexes stabilizes the trivalent state. In the Pacific Ocean, 80% of the thallium was found to occur as Tl(lll), and only 20% as the sum of Tl(l) and alkylthallium compounds (Batley and Florence, 1975). As Tl(lll) is easily adsorbed and coprecipitated, it continuously moves down to the sediments. 

Deep Ocean— The deep ocean environment is very different from the ocean at the surface. At sites in the North Atlantic and North Pacific Oceans, oxygen, temperature, and salinity vary with depth. At the ocean surface, the oxygen concentration in the North Pacific is 1.4 times the oxygen content in the North Atlantic. In addition, both the surface temperature and surface salinity are lower in the North Pacific than in the North Atlantic. Below about 1500 m, however, temperature and salinity levels are approximately the same at these two ocean sites [1,6. ... 

The oxygen concentration also varies with seawater depth, as shown in Fig. 2. This figure compares the concentration level with depth at sites in both the North Atlantic and North Pacific Oceans. As the depth is increased to an intermediate level, the oxygen concentration decreases at both sites however, the reduction in oxygen is much greater in the Pacific Ocean than in the Atlantic. As the depth is then increased even further, the concentration of oxygen increases once again at both ocean sites [6. ... 

---