Ocean Southern

Middle Atlantic Indian Ocean Pacific Ocean Southern Ocean South Atlantic North Atlantic... 

Pacific Ocean Atiantic Ocean indian Ocean Southern Ocean World Ocean average Crustai abundance Enrichment factor Shallow marine Lakes... 

Latitudes Pacific Ocean Atlantic Ocean Indian Ocean Southern Ocean Global Oceans... 

Deep-sea manganese nodules represent a significant potential mineral resource. Whereas the principal constituent of these deposits is manganese, the primary interest has come from the associated metals that the nodules can also contain (see Ocean rawmaterials). For example, metals can range from 0.01—2.0% nickel, 0.01—2.0% copper, and 0.01—2.25% cobalt (12). Recovery is considered an economic potential in the northwestern equatorial Pacific, and to a lesser degree in the southern and western Pacific and Indian Oceans (13—18). 

Changes in surface temperature elsewhere in the globe are likely to have a lesser impact on carbon or DMS production. For example, the warming that a doubling of atmospheric COj could produce in the Southern Ocean has been modelled to lead to decreased carbon uptake, but enhanced biological productivity, due to the temperature effect on phytoplankton growth." This would lead to an approximately 5% increase in DMS production and a lesser increase in CCN. There is thus a negative feedback here, but only of minor impact. 

Joint ventures such as the revitalization of the Panama Canal Railway—a 47-mile railroad running parallel to the Panama Canal and connecting ports on the Atlantic and Pacific Oceans—should be more common. Kansas City Southern Railroad and Mi-... 

Potential Effects of Increased Ultraviolet Radiation on the Productivity of the Southern Ocean... 

UV levels. The implications of these findings to our understanding of the trophodynamics of the Southern Ocean and the bearing these have on global marine... 

Effect of UV on Productivity of the Southern Ocean. Has ozone depletion over Antarctica affected the productivity of the Southern Ocean There is no easy answer. First, one has to take into account the fact that the drastic decrease of ozone over Antarctica has been reported as recently as 1976, a relatively short time in the evolution of the organisms to develop mechanisms to cope with elevated UV. One of the most vexing problems in studying the effects of UV radiation on productivity, is a dearth of historical data on the level of UV. Without these baselines, normal fluctuations could easily be interpreted as decline in productivity. Second, there is a host of biotic and abiotic factors that play significant roles in governing the productivity of the Southern Ocean (40). Ultraviolet radiation is but one more complicating factor to be considered in an already stressful environment. 

Rivers transport suspended sediments derived from the disintegration of basin surface layers. With reduced velocity, sediment is deposited in the river channel. The finest material is carried to the sea. It has been estimated that the average mechanical denudation rate for continents is 0.056 mm year (35). This is based on a total suspended load of 13.5 x 10 metric tons year (S). Presently, about two-thirds of the world s total suspended sediment load derives from Southern Asia and large Pacific Islands. Berner has estimated the increase in sediment loss in the U.S. and world since prehuman times to be approximately 200% (35). Current estimated erosion rate from the major land forms is provided in Table I. The relatively recent construction of large sediment trapping dams that normally caused sediment to be deposited in river valleys or transported to the ocean has drastically reduced sediment yields in great rivers. 

Because temperature (T) and salinity (S) are the main factors controlling density, oceanographers use T-S diagrams to describe the features of the different water masses. The average temperature and salinity of the world ocean and various parts of the ocean are given in Fig. 10-3 and Table 10-3. The North Atlantic contains the warmest and saltiest water of the major oceans. The Southern Ocean (the region around Antarctica) is the coldest and the North Pacific has the lowest average salinity. 

As a result of these factors (wind, Ekman transport, Coriolis force) the surface ocean circulation in the mid-latitudes is characterized by clockwise gyres in the northern hemisphere and the counterclockwise gyres in the southern hemisphere. The main surface currents around these gyres for the world s oceans are shown in Fig. 10-6. The regions where Ekman transport tends to push water together are called convergences. Divergences result when surface waters are pushed apart. 

Over 20% of the world s open ocean surface waters are replete in light and major nutrients (nitrate, phosphate, and silicate), yet chlorophyll and productivity values remain low. These so-called "high-nitrate low-chlorophyll" or HNLC regimes (Chisholm and Morel, 1991) include the sub-arctic North Pacific (Martin and Fitzwater, 1988 Martin et al, 1989 Miller et al, 1991), the equatorial Pacific (Murray et al, 1994 Fitzwater et al, 1996) and the southern Ocean (Martin et al.,... 

Gaillard, J.-F. and Treguer, P. (1997). Antares I France JGOFS in the Indian Sector of the Southern Ocean Benthic and water column processes. Deep-Sea Res. 1144, 951-1176. 

Smetacek, V., de Baar, H. J. W., Bathmann, U. V. et al. (eds) (1997). Ecology and biogeochemistry of the Antarctic Circumpolar current during austral spring Southern Ocean JGOFS Cruise ANT X/6 of R.V. Polarstem. Deep-Sea Res. II44,1-519. 

Southern Ocean JGOFS The UK "Sterna" Study in the Bellingshausen Sea. Deep-Sea Res. II 42, 907-1335. 

MSA and SOl histories from Antarctica (Legrand et al, 1991) imply a very different response (Fig. 18-18) for the southern oceans than for those of the north. While not... 

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