Oceans density

The most common litter item are small pieces of plastics whose lengths are on the order of a few millimeters. An important component are thermoplastic resin pellets and beads that are raw materials, mostly polypropylene and polyethylene, intended for manufecture into commercial items. Loss during ship transport and stormwater runoff are major sources of the pellets and beads to the ocean. Densities of 3500 per km have been reported floating on the surfece in the Sargasso Sea. On the beaches of New Zealand located near industrialized areas, concentrations as high as 100,000 per km are now being observed. The pellets and beads are carried by currents until they are either... 

The 5 0 from the calcite tests of benthic foraminifera preserved in ocean sediments can be used to estimate upper-ocean density because both the 5 0 of calcite (S Ocaicite) and density increase as a result of increasing salinity or decreasing temperature (Lynch-Stieglitz et al., 1999a). The fractionation between calcite precipitated inorganically and the water in which it forms increases by 0.2%c for every 1 °C decrease in temperature (Kim and O Neil, 1997). The relationship between S Ocaidte and salinity is more complex. The S Ocaidte reflects the 5 0 of the water in which the foraminifera grew. The 5 0 of seawater (S Owater) primarily reflects patterns of evaporation and freshwater influx to the surface of the ocean. Because salinity also reflects these same processes, salinity and... 

The oceans are subdivided into surface (100—1000-m) ocean and deep ocean. The zone separating the warmer, surface water from the lower, cooler layer (oceanic thermocline) is characterized by a density gradient that prevents mixing. 

Diamonds were first discovered in ancient times in India and Borneo and later in Brazil in 1670 in alluvial deposits where water had sorted minerals on the basis of density and toughness. This type of tumbling often concentrates the better quality crystals such as those found in the ocean off the west coast of Africa. Exploration can be done by stream panning or drilling in conjunction with a search for the heavy mineral assemblages that accompany diamond. Alluvial deposits account for about 40% of the diamond found in primary sources. 

Extracted from U.S. Standard Atmosphere, 1976, National Oceanic and Atmospheric Administration, National Aeronautics and Space Administration and tte U.S. Air Force, Washington, 1976. Z = geometric altitude, T = temperature, P = pressure, g = acceleration of gravity, M = molecular weight, a = velocity of sound, i = viscosity, k = thermal conductivity, X = mean free path, p = density, and H = geopotential altitude. The notation 1.79.—5 signifies 1.79 X 10 . ... 

In the corrosion protection of marine structures, it is often found that the corrosion rate decreases strongly with increasing depth of water, and protection at these depths can be ignored. Investigations in the Pacific Ocean are often the source of these assumptions [7], However, they do not apply in the North Sea and other sea areas with oil and gas platforms. Figure 16-1 is an example of measurements in the North Sea. It can be seen that flow velocity and with it, oxygen access, is responsible for the level of protection current density. Increased flow velocity raises the transport of oxygen to the uncoated steel surface and therefore determines the... 

Buoyancy in some form is employed in nearly all categories of underwater and surface systems to support them above the ocean bottom or to minimize their submerged weight. The buoyant material can assume many different structural forms utilizing a wide variety of densities. The choice of materials is severely restricted by operational requirements, since different environmental conditions exist. For example, lighter, buoyant liquids can be more volatile than heavier liquids. This factor can have a deleterious effect on a steel structure by accelerating stress corrosion or increasing permeability in reinforced plastics. 

Before describing these thermodynamic variables, we must talk about their properties. The variables are classified as intensive or extensive. Extensive variables depend upon the amount while intensive variables do not. Density is an example of an intensive variable. The density of an ice crystal in an iceberg is the same as the density of the entire iceberg. Volume, on the other hand, is an extensive variable. The volume of the ocean is very different from the volume of a drop of sea water. When we talk about an extensive thermodynamic variable Z we must be careful to specify the amount. This is usually done in terms of the molar property Zm, defined as... 

Amount of ocean water having a density between pi and P2-... 

The magnitude and direction of the net flux density, F, of any gaseous species across an air-water interface is positive if the flux is directed from the atmosphere to the ocean. F is related to the difference in concentration (Ac), in the two phases by the relation... 

The flux of particles in the other direction, deposition on the ocean surface, occurs intermittently in precipitation (wet deposition) and more continuously as a direct uptake by the surface (dry deposition). These flux densities may be represented by a product of the concen-... 

The sediment surface separates a mixture of solid sediment and interstitial water from the overlying water. Growth of the sediment results from accumulation of solid particles and inclusion of water in the pore space between the particles. The rates of sediment deposition vary from a few millimeters per 1000 years in the pelagic ocean up to centimeters per year in lakes and coastal areas. The resulting flux density of solid particles to the sediment surface is normally in the range 0.006 to 6 kg/m per year (Lerman, 1979). The corresponding flux density of materials dissolved in the trapped water is 10 to 10 kg/m per year. Chemical species may also be transported across the sediment surface by other transport processes. The main processes are (Lerman, 1979) ... 

In this section we briefly review what controls the density of seawater and the vertical density stratification of the ocean. Surface currents, abyssal circulation, and thermocline circulation are considered individually. 

To a first approximation the vertical density distribution of the ocean can be described as a three-layered structure. The surface layer is the region from the sea surface to the depth having a... 

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. 

Figure 4. Time series profiles of and temperature, potential density, Chi a, and nitrate (Slagle and Heimerdinger 1991) at 47°N, 20°W (Atlantic Ocean) in April-May 1989. Dashed vertical line represents estimated activity (Chen et al. 1986). The evolution of " Th/ U disequilibrium with time follows that of Chi a and nitrate, confirming the observations illustrated in Figure 3. The series of profiles taken approximately one week apart permits application of a nonsteady state model to the data. [Reprinted from Buesseler et al., Deep-Sea Research /, Vol. 39, pp. 1115-1137, 1992, with permission from Elsevier Science.]...

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