Warm Surface Water

Some petroleum geologists believe that there may be more methane trapped in hydrates than what is associated with natural gas reserves. However, as an energy source, there is considerable uncertainty whether this methane can ever be recovered safely, economically, and with minimal environmental impact. The Russians have experimented with the use of antifreeze to break down hydrates at some onshore locations in Siberia. But perhaps a more promising approach would be to pipe warm surface water to the bottom to melt the hydrates, with a collector positioned to convey the gas to the surface. Another approach might be to free methane by somehow reducing the pressure on the methane hydrates. 

There are three potential types of OTEC power plants opcii-cyclc, closed-cycle, and hybrid systems. Open-cycle OTEC systems exploit the fact that water boils at temperatures below its normal boiling point when it is under lower than normal pressures. Open-cycle systems convert warm surface water into steam in a partial vacuum, and then use this steam to drive a large turbine connected to an electrical generator. Cold water piped up from deep below the oceans surface condenses the steam. Unlike the initial ocean water, the condensed steam is desalinated (free of salt) and may be collected and used for drinking or irrigation. 

Closed-cycle OTEC systems use warm surface waters passed through a heat exchanger to boil a working fluid that has a low boiling point, such as... 

Conventional T-S diagrams for specific locations in the individual oceans are shown in Fig. 10-4. The inflections in the curves reflect the inputs of water from different sources. The linear regions represent mixing intervals between these core sources. For example, in the Atlantic Ocean the curves reflect input from Antarctic Bottom Water (AABW), North Atlantic Deep Water (NADW), Antarctic Intermediate Water (AIW), Mediterranean Water (MW), and Warm Surface Water (WSW). 

South America to about the date line (180 ). These trade winds also drive near-equatorial surface flow westward as the South Equatorial Current (SEC). This piles up warm surface water in the western Pacific to create a deep warm pool and results in depression of the depth of the thermocline from east to west. The westward flow in the surface SEC is partly compensated by a return flow to the east in the thermocline ( 150m) called the Equatorial Undercurrent (EUC). 

S], [DA], [DP], represent respectively the concentrations of the given element in warm surface water, deep Atlantic water, and deep Pacific water. 

In the surface waters, geographic variability in 2CO2 and TA. are caused by the effects of temperature on CO2 solubility and by variations in the local rates of photosynthesis and biogenic calcification. In general, surfece water 2CO2 concentrations are lowest in warm surface waters due to the low solubility of CO2 at higher temperatures. The lower influx of CO2 also causes warm surface waters to have a higher carbonate ion concentration as compared to cold surfece waters. Carbonate ion concentrations are... 

Since the oceans comprise over 70% of the earth s surface area, the absorbed solar energy that is stored as latent heat of the oceans represents a very large potential source of energy. As a result of variation in the density of ocean water with temperature, the ocean water temperature is not uniform with depth. Warm surface ocean water with low density tends to stay on the surface and cold water with high density within a few degree of 4°C tends to settle to the depths of the ocean. In the tropics, ocean surface temperatures in excess of 25° C occur. The combination of the warmed surface water and cold deep water provides two different temperature thermal reservoirs needed to operate a heat engine called OTEC (ocean thermal energy conversion). Since the temperature difference of the OTEC between the heat source and the heat sink is small, the OTEC power plant cycle efficiency... 

Carbon enters the atmosphere mainly as the result of respiration and burning of any kind. The oceans provide a slower, smaller pathway for carbon to enter the atmosphere. Dissolved carbon dioxide moves through the oceans waters in currents. At some places on the planet, mainly near the equator, currents bring cold water rich in carbon dioxide from deep in the ocean to the sea surface, where the Sun warms it. These warm surface waters naturally release carbon dioxide into the atmosphere. 

Carbon dioxide mainly exits the oceans at the interface with the atmosphere. Warm surface waters easily release carbon dioxide into the atmosphere. When warm waters rise to the surface, mainly near the equator, carbon dioxide is transferred from the water to the air. Because of this, the sea is a source of carbon for the carbon cycle as well as a carbon sink. 

T) Warm surface water is used to vaporize ammonia. 

Loss rates of both CCI4 and Fll in anoxic waters are probably due to biological rather than chemical removal (Lee et al., 1999). It also seems likely that some of the chlorofluorocarbons are removed in fully oxygenated surface waters. Observations show that there is a deficit of CCI4 in the Antarctic surface and bottom waters (Meredith et al., 1996). Finally, fluorinated compounds such as CFC-113 are degraded in warm surface waters of the temperate North Atlantic, the tropical western Pacific, the Eastern Mediterranean, and even the Weddell Sea (Roether et al., 2001). CFC-113 depletions were —3% yr, with possibly accelerated rates in the mixed layer or near the surface. 

Bacastow R. B. (1996) The effect of temperature change of the warm surface waters of the oceans on atmospheric CO2. Global Biogeochem. Cycles 10, 319—334. 

Cadmium in seawater has a nutrient-like profile, with depleted values in warm surface waters, and... 

Two additional processes besides carbon chemistry keep the atmospheric CO2 lower than it otherwise would be. One process is referred to as the solubility pump and the other as the biological pump. The solubility pump is based on the fact that CO2 is more soluble in cold waters. In the ocean, CO2 is —2 times more soluble in the cold mid-depth and deep waters than it is in the warm surface waters near the equator. Because sinking of cold surface waters in Arctic and Antarctic regions forms these mid-depth and deep waters, the formation of these waters with high CO2 keeps the CO2 concentration of the atmosphere lower than the average concentration of surface waters. 

The isotope effects (both kinetic and equilibrium) that deplete deuterium, D, and 0 in evaporated water vapor must enrich these isotopes in the surface seawater left behind. This isotope effect can be seen in longitudinal transects of surface waters in both the Atlantic and Pacific Oceans (Fig. 5.12), which indicate a broad maximum of between roughly 30° north and south latitudes. Salinity maxima are evident over the same latitude band, with a slight minimum near the Equator. The parallel maxima in and salinity result because net evaporation from warm surface waters at lower latitudes preferentially leaves behind both H2 0 molecules and salt. Rainfall in excess of evaporation from atmospheric convection cells rising near the Equator is recorded by both a salinity and a minimum. 

Isotope Half life (y) Warm Surface Water N Atlantic Bottom Water N Pacific Bottom Water... 

Both warm surface water (27°C) and cold deep water (5°C) enter work producing device, and they leave at a common temperature. 

Table 9.2 Model calculation using the PHREEQC program (Parkhurst 1995) on a sample of warm surface water from the ocean near the equator. The lower part of the table shows the results for a theoretical = 0.0) precipitation...

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