Salinity Atlantic Ocean

Local conditions may modify this profoundly in special areas. In the Arctic and Antarctic, and where there is dilution by large rivers, the salinity may be considerably less, and it may vary greatly according to season. Salinity is well below normal in the Baltic, and may fall nearly to zero at the head of the Gulf of Bothnia. In enclosed seas like the Mediterranean, Black Sea and Red Sea, on the other hand, where there is rapid evaporation, salinity may reach 40 parts per thousand. The total salt content of the inland Dead Sea is 260 g/kg compared to 37 g/kg for the Atlantic Ocean. 

Variability of Seawater Vertical sections through seawater showing the distribution of temperature, salinity, and oxygen for the Pacific Ocean and Western Atlantic Ocean are shown in Figures 21.3 and 21.4. The global variability of natural seawater and its effects on corrosion have been reviewed in particular with respect to seasonal variation of temperature, salinity, oxygen and pH in the Pacific surface water. Data is also given on... 

Fig. 21.4 Vertical sections showing distribution of temperature, salinity, and oxygen in the Western Atlantic Ocean (After Wiist). (After Sverdrup, H. U., Oceanography for Meteorologists,...

Evaporite deposition is a much more episodic process and thus difficult to quantify. Because seawater is significantly undersaturated with respect to common evaporitic minerals, like gypsum and halite, evaporites are only formed when restricted circulation develops in an ocean basin in which evaporation exceeds precipitation. A geologically recent example is the Mediterranean Sea of 5-6 Myr ago. At this time excess evaporation exceeded the supply of ocean water through shallow inlet(s) from the Atlantic Ocean. As salinity increased, first CaS04, then NaCl precipitated. Over time, salt deposits 2-3 km thick formed. This thickness represents about 40 desiccations of the entire... 

Figure 3. Time series of nitrate (Slagle and Heimerdinger 1991) and dissolved, particulate, and total in surface water at 47°N, 20°W (Atlantic Ocean) in April-May 1989. activity calculated as 0.0686 salinity (Chen et al. 1986). The production of biogenic particles during the bloom enhances the scavenging of Th, resulting in growing disequilibrium with time due to sinking of particles.

The basement complex for the Patagonian desert and arid northeastern Brazil is formed by metamorphosed Precambrian rocks. Landscapes are characterized by level erosion surfaces of different ages. The landscape is dissected by a large number of valleys. Large depressions are filled with marine and continental beds of sedimentary rocks. Rocks in the Andean system, that stretches the entire length of the west side of the continent, vary greatly. Many depressions are filled with sediments. In addition, many active volcanoes are responsible for periodic lava flows and the deposition of volcanic ash. East of the Andes, the land surface is level and slopes towards the Atlantic Ocean. Broad depressions contain saline or sodic soils. 

Longitudinal profiles in the Atlantic Ocean at about 25°W. (a) Potential temperature (°C), (b) salinity, (o) potential density (0 dbar), (d) potential density (4000 dbar), and (e) dissolved oxygen ( j,mol/kg). Source-. After Talley, L. (1996). Atlantic Ocean Vertical Sections and datasets for selected lines. http /sam.ucsd.edu/vertical.sections/Atlantic.html. Scripps Institute of Oceanography, University of California - San Diego. Data are from WOCE hydrographic program. (See companion website for color version.)... 

Depth profiles of (a) salinity (%o), (b) dissolved oxygen (ml /L), and (c) percent saturation of dissolved oxygen in the Southeastern Atlantic Ocean (9°30 W 11°20 S). Samples were collected in March 1994. Dotted lines represent the curves generated by the one-dimensional advection-diffusion model (see text for details). The values of Dz, Vz, and J are the ones that best fit the data. Data are from Java Ocean Atlas (http /odf.ucsd.edu/joa). Values of percent saturation of oxygen less than 100 reflect the effects of aerobic respiration. Values greater than 100 indicate a net input, such as from photosynthesis. (See companion website for color version.)... 

Delaygue et al. (2000) have modeled the present day 0 distribution in the Atlantic and Pacific Ocean and its relationship with salinity (see Fig. 3.19). A good agreement is found between observed and simulated 5 0-values using an oceanic circulation model. As shown in Fig. 3.19 the Atlantic Ocean is enriched by more than 0.5%c relative to the Pacific Ocean, but both ocean basins show the same general patterns with high 0-values in the subtropics and lower values at high latitudes. 

In the case of these two regions there is a natural source of airborne salinity the waters of the Atlantic Ocean, the Gulf of Mexico and the Caribbean Sea. Airborne salinity plays an important role in determining corrosion aggressivity in Cuba [1-4] and in the Yucatan Peninsula [2, 5-6], Other anthropogenic contaminants can be present also in this region, particularly sulfur compounds coming from the oil production and manufacture industries and... 

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

The CCcu appeared to be linearly dependent on the concentration factor only in the upper part of the estuary. No increase in the CCcu couW be observed after concentration at higher salinities. The riverine colloidal material apparently coagulates to particles and floes at increasing salinity in the upper part of the estuary. These floes are retained by the 0.45 ym filter, thus no longer contributing to the complexation capacity of the "dissolved" fraction. This explains the non conservative behaviour of the CCcu n this part of the estuary (see later). Samples taken from the north Atlantic Ocean did not show an increase in CCcu> even aftar a concentration factor 200 times. 

Fig. 4. Schematic representation of surface currents in the north Atlantic Ocean and stations where surface waters were collected. Areas I to V indicate regions with common temperature, salinity and nutrient characteristics.

North Atlantic Ocean. Surface samples in north Atlantic waters were collected at 20 stations in Tuly-August 1983. The area is influenced mainly by the Gulfstream, the North Atlantic Drift and the much colder East Greenland Current. The surface samples can be grouped into fives areas with common characteristics of temperature, salinity, phosphate and silicate concentrations, Fig. 4 (Kramer, 1986). 

Figure 4.7. The mean vertical distribution of (a) alkalinity and (b) total CO2 concentration normalized to the mean world ocean salinity value of 34.78. NA = North Atlantic, SA = South Atlantic, NP = North Pacific, SP = South Pacific, NI = North Indian, SI = South Indian, and A A = Antarctic region. (After Takahashi etal., 1980b.)...

Ocean, which is slightly higher than that of the Atlantic Ocean. The third driving force is the difference between the salinity and the temperature of the waters near the equator and near Greenland in the north. 

O2 can be used as a tracer to help identify the origin of water masses. The warm, saline intrusion into the Atlantic Ocean from the Mediterranean Sea is relatively O2 deficient. Alternatively, the waters down-welling from Polar Regions have elevated O2 concentrations. 

Figure 2.6 Air-sea flux densities of N2 (bold lines) calculated as F = (0.39ujq ) (SRCair-Cair) (Scn2/660) (Wanninkhof, 1992). SR stands for the N2 saturation ratio and Um stands for the wind speed in a height of 10m. Water temperature and salinity were set to 25° C and 35, respectively. C ir is the equilibrium concentration of atmospheric N2 and was calculated with the equation given by Hamme and Emerson (2004). The dashed lines represent maximum (3110 pmol N m day ) and minimum (161 pmol N m day ) mean N2 fixation rates for the North Atlantic Ocean (Capone et a/., 2005).

Sea water samples were collected from (a) Chesapeake Bay at the Patuxent Naval Air Station at high tide with salinity of the samples varying between 9%c and 16%o and pH between 7.9 and 8.2 (b) the Atlantic Ocean about 30 km east of Ocean City, Md., salinity 31%c, pH 8.2 (c) the Caribbean Sea oflF Coco Solo, Panama Canal Zone, salinity 32.8%. and (d) the Gulf of Mexico, 350 km WNW of Key West, Fla., salinity 35.4%., pH 8.1. The particulate material found in natural sea water samples was concentrated and separated from the bulk of the water sample by centrifugation at 18,000 g. 

Physical processes associated with hydrothermal plumes may affect their impact upon ocean geochemistry because of the fundamentally different hydrographic controls in the Pacific versus Atlantic Oceans, plume dispersion varies between these two oceans. In the Pacific Ocean, where deep waters are warmer and saltier than overlying water masses, nonbuoyant hydrothermal plumes which have entrained local deep water are typically warmer and more saline at the point of emplacement than that part of the water column into which they intrude (e.g., Lupton et al, 1985). The opposite has been observed in the Atlantic Ocean where deep waters tend to be colder and less saline than the overlying water column. Consequently, for example, the TAG nonbuoyant plume is anomalously cold and fresh when compared to the background waters into which it intrudes, 300-400 m above the seafloor (Speer and Rona, 1989). 

Salinity-normalized (S = 35) total alkalinity. Ay n> versus salinity-normalized dissolved inorganic carbon, DICn, for the world s ocean. Data are for the deep ocean at depths >2.5 km except for the section labeled North Atlantic Shallow," which is 100-1000 m in the North Atlantic Ocean. Lines indicate different DICn At.n ratios. (See Plate 2.)... 

Along the coast, salinity levels can vary extremely. In areas where a river enters the ocean, or places where there is a lot of precipitation, salinity drops below average. For example, the water at the mouth of the Amazon River, where it runs into the Atlantic Ocean, has a salinity that is 25 percent lower than surrounding water. The same thing happens where rivers empty into bays and harbors. 

A fresh—brackish-water (significantly less saline than seawater) wedge extends under the Atlantic Ocean as far as 120 km from shore, down to depths greater than 600 m. This phenomenon was reported in papers cited earlier and is discussed in considerable detail by Kohout (1981), and Pauli and Dillon (1981). The evidence suggests that boundaries are much smoother and more regionally continuous than on land. These boundary characteristics are consistent with predictions based on the mobility of water influenced by artesian circulation (land) relative to the mobility of water in largely diffusive fluxes (beneath the sea). 

The existence of fresh water beneath the Atlantic Ocean, to the edge of the U.S.A. continental shelf, has been well documented in the JOIDES and AMCOR drill holes (Manheim, 1967 Hathaway et al., 1979 Kohout, 1981 Pauli and Dillon, 1981). New electrical-logging data from the COST GE-J well confirm the existence of brackish water in the upper 900 m. Moreover, a special agreement by Tenneco Oil Co. permitted the U.S. Geological Survey to run a drill-stem test at 350-m depth, in a wildcat well (Fig. 1, T) 85km seaward of Jacksonville, Florida. A drill-stem test confirmed presence of brackish water having less than half the salinity of seawater (R. Johnston, pers. commun., 1979). 

Duplessy, J.-C., Labeyrie, L. D., Juillet-Leclerc, A., Maitre, F., Duprat, j. Sarnthein, M. 1991. Surface salinity reconstruction of the North Atlantic Ocean during the last glacial maximum. Oceanologica Acta, 14, 311-324. 

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