Salinity average ocean

Fig. 11-7 Distribution of dissolved carbon species in seawater as a function of pH. Average oceanic pH is about 8.2. The distribution is calculated for a temperature of 15°C and a salinity of 35%o. The equilibrium constants are from Mehrbach et al. (1973).

Average Salinity of Ocean Water (Grams per Kilogram)... 

The salinity of ocean waters is not the same everywhere. The average salinity of ocean waters is 35%o. (35 g of dissolved salts in 1000 g of water.) Salinity of ocean waters depends upon the amount of evaporation, addition of fresh water from the rivers and rainfall and humidity. 

Schrag, 2001). Chloride is proportional to salinity, a direct measure of ice volume. The average oceanic value can only be recast as ice... 

Salinity is a measure of the mass of salts dissolved in seawater. It is usually measured in grams of salt per kilogram of seawater. The average salinity of ocean water is about 35 g per kg, so ocean water contains about 3.5% dissolved salts. Most of these salts dissociate in water and are present in the form of ions. Table 26-2 lists the ions in seawater. Note that chlorine and sodium are the most abundant ions in seawater. Although Earth s oceans are vast, the proportions and quantities of dissolved salts are nearly constant in all areas. Indeed, they have stayed almost the same for hundreds of millions of years. Why is this so As rivers, volcanoes, and atmospheric processes add new substances to seawater, elements are removed from the oceans by biological processes and sedimentation. Thus, the oceans are considered to be in a steady state with respect to sahnity. 

Anyone who has tasted seawater knows that it is salty. Although salinity is fairly constant throughout most of the ocean, it is exceptionally variable near the shore. Salinity refers to the amount of dissolved minerals, or salts, in water. The average salinity of ocean water is 35 parts per thousand, abbreviated as 35%o (per ml). (The symbol %o is similar to percent but refers to parts per thousand instead of parts per hundred.)... 

Thermal expansion (and contraction) of the oceans, caused by a combination of increasing (decreasing) temperature and salinity, accounts for seasonal and interannual variations in sea level. Thermal expansion and contraction are not large enough, however, to account for the differences in sea level over tens of thousands of years. Warming the entire ocean from 0 "C to the current global average ocean temperature, for example, would result in a sea level rise of only about 10 m. 

Seawater is often referred to as saline water. The salinity of seawater is the mass in grams of dry salts present in 1 kg of seawater. In the world ocean, salinity averages about 35. To put it another way, seawater contains about 3.5% dissolved salts by mass. The list of elements present in seawater is very long. Most, however, are present only in very low concentrations. T TABLE 18.5 lists the 11 ionic species most abundant in seawater. 

An ocean is a major body of saline water, and a principal component of our planet s remarkable hydrosphere. Approximately 71% of the Earth s surface (an area of 361 million km (139 million mi ) is covered by ocean, a continuous body of seawater that is customarily divided into several principal named oceans and smaller named seas. More than half of this area is deeper than 3,000 m (9,842 ft). Average oceanic salinity is around 35 parts per thousand (ppt) (3.5%), and nearly all seawater has a salinity in the range of 31-38 ppt. Interestingly, the place furthest from the world-ocean—that is, the official pole of inaccessibility is in Asia (46° 17 N 86° 40 E), according to Garcia-Castellanos and Lombardo (2007). The volume of Earth s ocean is approximately 1.3 billion km (0.312 billion mi ), and its average depth is 3,790 m (12,434 ft). The vast volume of the deep ocean (anything below 200 m, 656 ft) covers about 66% of our Earth s surface. 

The absence of any osmoregulatory function may explain the fact that echinoderms have not been able to adapt to freshwater. However, some species, such as Asterias rubens, have been found in the Baltic Sea, where the salinity is only 8%o, and holothurians are present in the Black Sea (18%o) the average salinity of oceans is 35%o. The water in which echinoderms live moves relatively freely through their body, suggesting that these invertebrates are in osmotic and ionic balance with their environment. 

Chlorine is the twentieth most abundant element in crustal rocks where it occurs to the extent of 126 ppm (cf. nineteenth V, 136 ppm, and twenty-first Cr, 122 ppm). The vast evaporite deposits of NaCl and other chloride minerals have already been described (pp. 69, 73). Dwarfing these, however, are the inconceivably vast reserves in ocean waters (p. 69) where more than half the total average salinity of 3.4 wt% is due to chloride ions (1.9 wt%). Smaller quantities, though at higher concentrations, occur in certain inland seas and in subterranean brine wells, e.g. the Great Salt Lake, Utah (23% NaCl) and the Dead Sea, Israel (8.0% NaCl, 13.0% MgCU, 3.5% CaCU). 

Variations of salinity In the major oceans the salinity of sea water does not vary widely, lying in general between 33 and 37 parts per thousand, a figure of 35 parts per thousand, equivalent to 19-4 parts per thousand chlorinity is commonly taken as the average for open-sea water. 

Table 10-3 Average temperatures and salinity of the oceans, excluding adjacent seas ...

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. 

Fig. 10-4 Average temperature/salinity diagrams for Pacific Oceans. (Reproduced with permission from G. L. Oceanography," pp. 138-139, Pergamon Press.)...

The graph shows the average salinity of Earth s oceans over time. According to these data, which of the following statements is true ... 

B The average salinity of Earth s oceans remains fairly constant over time. 

We turn our attention now to the hydrothermal brines of the Red Sea. An oceanic survey in 1963 discovered pools of hot, saline, and metal-rich brines along the axial rift of the Red Sea (Degens and Ross, 1969 Hoffmann, 1991). The dense brines pond in the rift s depressions, or deeps. The Atlantis II deep contains the largest pool, which measures 5 x 14 km and holds about 5 km3 of supersaline brine. The deep holds two layers of brine. The lower brine contains about 25 wt.% dissolved salts and exists at temperatures up to 60 °C. Table 6.8 shows the brine s average composition. A somewhat cooler, less saline water overlies the lower brine, separating it from normal seawater. 

Since the mass ratio is multiplied by 1000, the units of salinity are parts per thousand, symbolized by %o. The average salinity of seawater is 35%o, which is eqifivalent to a 3.5% salt solution. As shown in Figure 3 3, 99% of the seawater in the ocean has a salinity between 33%o and 37%o. Note that the temperature of seawater is far more variable, ranging from -2° to 30°C with an average of 3 5°C. Fifty percent of the water has a salinity between 34.6%o and 34.8%o and a temperature between 1.3°C and 3.8°C. 

Annually averaged salinity of surface seawater In the world s oceans. Source-. After Levltus, S. (1982). Climatological atlas of the world ocean. NOAA Professional Paper 13, U.S. Government Printing Office, Washington, DC. (See companion website for color version.)... 

Sodium chloride is widely distributed in nature. Oceans are the vast source of sodium chloride. It occurs in seawater at an average concentration of 2.68 wt%. It also occurs in many inland saline waters and in salt deposits in sedimentary rocks, as the mineral hahte. 

The Atlantic Ocean has the highest average salinity and the Arctic Ocean has the least average salinity. How do we express salinity ... 

Salinity is defined here as the grams of dissolved solids (or inorganic dissolved compounds) per kg of seawater, or parts per thousand (or as a per thou-sand%o). Alternatively, it can be defined as the mg/L or mmol/L of the major ions (i.e., those present in concentrations above 1 ppm). The total concentration of dissolved solids ranges from 7,000 ppm for the Baltic Sea, to an average of 35,000 ppm in large oceans, and up to 40,000 ppm in regions where evaporation is high and inputs are low, such as the Red Sea. 

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