tailieunhanh - Volume 13 - Corrosion Part 13

Tham khảo tài liệu 'volume 13 - corrosion part 13', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Fig. 26 Pacific Ocean pH at a depth of 500 m 1640 ft . Source Ref 5 Fig. 27 Pacific Ocean pH at a depth of 1000 m 3280 ft . Source Ref 5 Profiles of pH with depth for the two open ocean locations are shown in Fig. 28. A comparison of the corresponding pH and oxygen profiles from Fig. 16 and 28 reveals the closely coupled nature of their relationship through the carbon dioxide system as discussed above. The oxygen and pH minima are reached at the same depth for a given location as was predicted. The deep north Pacific water is from to pH units more acidic than that in the North Atlantic primarily because of the increased oxidation of organic matter in the North Pacific. Fig. 28 Comparison of pH-depth profiles for open ocean sites 2 and 6 see Fig. 5 . Note that the data for the south Pacific are highest at the surface but are intermediate at depths greater than 500 m 1640 ft . Source Ref 5 Profiles of pH for the coastal waters off Oregon and New Jersey are shown in Fig. 11 and 13 respectively. The close correlation between the shapes of the oxygen and pH profiles in both winter and summer for the Oregon data in Fig. 11 is particularly striking. Upon close examination the oxygen and pH profiles in Fig. 13 do not appear to be closely related in the manner seen earlier. In March the water column is well mixed down to the bottom and the changes with depth of all four variables are small. In August however the dissolved oxygen profile is nearly independent of depth while the pH and temperature profiles show substantial changes. Based on salinity and temperature the oxygen saturation levels during August are about mL L in the surface waters and mL L in the deep water. The oxygen profile for August shows that the surface waters are nearly saturated while in the deep waters biological activity has used up enough oxygen and produced enough CO2 to decrease the pH--but not enough to produce a strong oxygen minimum. This indicates the danger inherent in .