WordNet

water containing salts; "the water in the ocean is all saltwater" (同)saltwater, brine
provide with water; "We watered the buffalo"
binary compound that occurs at room temperature as a clear colorless odorless tasteless liquid; freezes into ice below 0 degrees centigrade and boils above 100 degrees centigrade; widely used as a solvent (同)H2O
supply with water, as with channels or ditches or streams; "Water the fields" (同)irrigate
once thought to be one of four elements composing the universe (Empedocles)
secrete or form water, as tears or saliva; "My mouth watered at the prospect of a good dinner"; "His eyes watered"
a liquid necessary for the life of most animals and plants; "he asked for a drink of water"
fill with tears; "His eyes were watering"
turbulent water with swells of considerable size; "heavy seas"
a division of an ocean or a large body of salt water partially enclosed by land
wetting with water; "the lawn needs a great deal of watering"

PrepTutorEJDIC

海水
〈U〉水 / 《しばしば複数形で》『海』(『湖,川』)『の水』 / 《複数形で》流れる水;(海・川・湖などの)波立つ水《+of+名》 / 《複数形で》(特定の)水域,領海,近海 / 〈U〉潮位,水位;《the water》水面 / 〈U〉分泌液(涙・汗・尿など) / 〈U〉溶液,…水 / 《複数形で》(飲用の)鉱泉水 / 〈U〉(織物・金属などの)波紋 / …‘に'『水をかける』(まく,やる) / 〈動物〉‘に'水を飲ませる / …‘に'水を供給する;…‘を'潅漑(かんがい)する / 〈液体など〉‘を'水で割る,薄める《+名+down,+down+名》 / 〈織物・金属など〉‘に'波紋(波模様)をつける / 〈動物などが〉水を飲む:〈船・機関などが〉給水を受ける / 〈目・口などが〉分泌液を出す
《通例the~》《しばしば複数形で単数扱い》『海』,海洋 / 〈C〉《固有名詞につけるときはS-》(部分的に陸地に囲まれた)海,…海 / (波の状態から見た)海面,湖面,水面;(海・湖などの)波;大波,高波 / 〈U〉《the ~》船乗り(水兵)の仕事,海上生活 / 《a ~》大量(の…),たくさん(の…)《+『of』+『名』》

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2012/08/05 22:49:40」(JST)

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Seawater in the Strait of Malacca

Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, or 599 mM). This means that every kilogram (roughly one litre by volume) of seawater has approximately 35 grams (1.2 oz) of dissolved salts (predominantly sodium (Na⁺) and chloride (Cl⁻) ions). Average density at the surface is 1.025 g/ml. Seawater is denser than both fresh water and pure water (density 1.0 g/ml @ 4 °C (39 °F)) because the dissolved salts add mass without contributing significantly to the volume. The freezing point of seawater decreases as salt concentration increases. At typical salinity it freezes at about −2 °C (28 °F).^[1] The coldest seawater ever recorded (in a liquid state) was in 2010, in a stream under an Antarctic glacier, and measured −2.6 °C (27.3 °F).^[2]

Geochemistry

The thermal conductivity of seawater is 0.6 W/mK at 25 degC and a salinity of 35 g/kg.^[3] The thermal conductivity decreases with increasing salinity and increases with increasing temperature.^[4]

Salinity

Main article: Salinity

Annual mean sea surface salinity for the World Ocean. Data from the World Ocean Atlas^[5]

Salinity

Although the vast majority of seawater has a salinity of between 3.1% and 3.8%, seawater is not uniformly saline throughout the world. Where mixing occurs with fresh water runoff from river mouths or near melting glaciers, seawater can be substantially less saline. The most saline open sea is the Red Sea, where high rates of evaporation, low precipitation and river inflow, and confined circulation result in unusually salty water. The salinity in isolated bodies of water (for example, the Dead Sea) can be considerably greater still.

The density of surface seawater ranges from about 1,020 to 1,029 kg•m⁻³, depending on the temperature and salinity. Deep in the ocean, under high pressure, seawater can reach a density of 1,050 kg•m⁻³ or higher. Seawater pH is limited to the range 7.5 to 8.4. The speed of sound in seawater is about 1,500 metres/second, and varies with water temperature, salinity, and pressure.

Seawater composition (by mass) (salinity = 35)
Element	Percent	Element	Percent
Oxygen	85.84	Sulfur	0.091
Hydrogen	10.82	Calcium	0.04
Chloride	1.94	Potassium	0.04
Sodium	1.08	Bromine	0.0067
Magnesium	0.1292	Carbon	0.0028

Human impacts

Climate change, rising atmospheric carbon dioxide, excess nutrients, and pollution in many forms are altering global oceanic geochemistry. Rates of change for some aspects greatly exceed those in the historical and recent geological record. Major trends include an increasing acidity, reduced subsurface oxygen in both near-shore and pelagic waters, rising coastal nitrogen levels, and widespread increases in mercury and persistent organic pollutants. Most of these perturbations are tied either directly or indirectly to human fossil fuel combustion, fertilizer use, and industrial activity. Concentrations are projected to grow in coming decades, with negative impacts on ocean biota and other marine resources.^[6]

Compositional differences from freshwater

Seawater contains more dissolved ions than all types of freshwater.^[7] However, the ratios of solutes differ dramatically. For instance, although seawater contains about 2.8 times more bicarbonate than river water based on molarity, the percentage of bicarbonate in seawater as a ratio of all dissolved ions is far lower than in river water. Bicarbonate ions also constitute 48% of river water solutes but only 0.14% of all seawater ions.^[7]^[8] Differences like these are due to the varying residence times of seawater solutes; sodium and chlorine have very long residence times, while calcium (vital for carbonate formation) tends to precipitate much more quickly.^[8] The most abundant dissolved ions in seawater are sodium, chloride, magnesium, sulfate and calcium.^[9]

Origin

Diagram showing concentrations of various salt ions in seawater: Cl⁻ 55%, Na⁺ 30.6%, SO2−

4 7.7%, Mg²⁺ 3.7%, Ca²⁺ 1.2%, K⁺ 1.1%, Other 0.7%. Note that the diagram is only correct in units of wt/wt, not wt/vol or vol/vol.

**Total Molar Composition of Seawater (Salinity = 35)^[10]**
Component	Concentration (mol/kg)
H₂O	53.6
Cl⁻	0.546
Na⁺	0.469
Mg²⁺	0.0528
SO2− 4	0.0282
Ca²⁺	0.0103
K⁺	0.0102
C_T	0.00206
Br⁻	0.000844
B_T	0.000416
Sr²⁺	0.000091
F⁻	0.000068

Scientific theories behind the origins of sea salt started with Sir Edmond Halley in 1715, who proposed that salt and other minerals were carried into the sea by rivers after rainfall washed it out of the ground. Upon reaching the ocean, these salts concentrated as more salt arrived over time (see Hydrologic cycle.) Halley noted that most lakes that don’t have ocean outlets (such as the Dead Sea and the Caspian Sea, see endorheic basin), have high salt content. Halley termed this process "continental weathering".

Halley's theory was partly correct. In addition, sodium leached out of the ocean floor when the ocean formed. The presence of salt’s other dominant ion, chloride, results from outgassing of chloride (as hydrochloric acid) with other gases from Earth's interior via volcanos and hydrothermal vents. The sodium and chloride ions subsequently became the most abundant constituents of sea salt.

Ocean salinity has been stable for billions of years, most likely as a consequence of a chemical/tectonic system which removes as much salt as is deposited; for instance, sodium and chloride sinks include evaporite deposits, pore water burial, and reactions with seafloor basalts.^[11] Following the ocean's formation, sodium no longer leached from the ocean floor, but instead was captured in sedimentary layers covering the ocean bed. Plate tectonics possibly forces salt under the continental land masses, where it slowly leaches again to the surface.

Human consumption

Accidentally consuming small quantities of clean seawater is not harmful, especially if the seawater is taken along with a larger quantity of fresh water. However, drinking seawater to maintain hydration is counterproductive; more water must be excreted to eliminate the salt (via urine) than the amount of water from the seawater itself.^[12]

The renal system actively regulates sodium chloride in the blood within a very narrow range around 9 g/L (0.9% by weight).

In most open waters concentrations vary somewhat around typical values of about 3.5%, far higher than the body can tolerate and most beyond what the kidney can process. A point frequently overlooked in claims that the kidney can excrete NaCl in Baltic concentrations (2%) is that the gut cannot absorb water at such concentrations, so that there is no benefit in drinking such water. Drinking seawater temporarily increases blood’s NaCl concentration. This signals the kidney to excrete sodium, but seawater’s sodium concentration is above the kidney’s maximum concentrating ability. Eventually the blood’s sodium concentration rises to toxic levels, removing water from cells and interfering with nerve conduction, ultimately producing fatal seizure and heart arrhythmia.^{[citation needed]}

Survival manuals consistently advise against drinking seawater.^[13] A summary of 163 life raft voyages estimated the risk of death at 39% for those who drank seawater, compared to 3% for those who did not. The effect of seawater intake on rats confirmed the negative effects of drinking seawater when dehydrated.^[14] However the regulation of the uptake of seawater salts may be possible through the colon. The mother of the Robertson family who were castaway for 38 days in 1972, proposed the feasibility of hydration through unpottable water enemas.^{[citation needed]}

The temptation to drink seawater was greatest for sailors who had expended their supply of fresh water, and were unable to capture enough rainwater for drinking. This frustration was described famously by a line from Samuel Taylor Coleridge's The Rime of the Ancient Mariner:

"Water, water, everywhere,

And all the boards did shrink;

Water, water, everywhere,

Nor any drop to drink."

Although humans cannot survive on seawater, some people claim that up to two cups a day, mixed with fresh water in a 2:3 ratio, produces no ill effect. The French physician Alain Bombard survived an ocean crossing in a small Zodiak rubber boat using mainly raw fish meat, which contains about 40 percent water (like most living tissues), as well as small amounts of seawater and other provisions harvested from the ocean. His findings were challenged, but an alternative explanation was not given. In Kon-Tiki, Thor Heyerdahl reported drinking seawater mixed with fresh in a 40/60% ratio. A few years later another adventurer named William Willis claimed to have drunk two cups of seawater and one cup of fresh per day for 70 days without ill effect when he lost part of his water supply.^[15]

Most modern ocean-going vessels desalinate potable water from seawater using processes such as vacuum distillation or multi-stage flash distillation in an evaporator, or more recently by reverse osmosis. These energy intensive processes were not usually available during the Age of Sail. Larger sailing warships with large crews, such as Nelson's HMS Victory were fitted with distilling apparatus in their galleys.^[16]

Other land and marine animals such as fish, whales, sea turtles and penguins can adapt to a high saline habitat. For example, the kidney of the desert rat can concentrate sodium far more efficiently than the human kidney.

Notes

^ "U.S. Office of Naval Research Ocean, Water: Temperature". http://www.onr.navy.mil/Focus/ocean/water/temp3.htm.
^ Sylte, Gudrun Urd (May 24, 2010). "Den aller kaldaste havstraumen" (in Norwegian). forskning.no. http://www.forskning.no/artikler/2010/mai/250690. Retrieved May 24, 2010.
^ "Desalination and Water Treatment". aDepartment of Mechanical Engineering, Massachusetts Institute of Technology. April 2010. http://web.mit.edu/lienhard/www/Thermophysical_properties_of_seawater-DWT-16-354-2010.pdf. Retrieved 17 October 2010.
^ "Thermal conductivity of seawater and its concentrates". http://twt.mpei.ac.ru/tthb/2/Tab-5-5-13-2-Ther-Cond-Seawater.html. Retrieved 17 October 2010.
^ "World Ocean Atlas 2005". NOAA. http://www.nodc.noaa.gov/OC5/WOA05/pr_woa05.html. Retrieved 17 October 2010.
^ Doney, Scott C. (June 18, 2010). "The Growing Human Footprint on Coastal and Open-Ocean Biogeochemistry". Science Magazine 328 (5985): 1512–1516. doi:10.1126/science.1185198. http://www.sciencemag.org/content/328/5985/1512.full. Retrieved 16 December 2011.
^ ^a ^b Gale, Thomson. "Ocean Chemical Processes". http://www.waterencyclopedia.com/Mi-Oc/Ocean-Chemical-Processes.html. Retrieved December 2, 2006.
^ ^a ^b Pinet, Paul R. (1996). 'Invitation to Oceanography. St. Paul: West Publishing Company. pp. 126, 134–135. ISBN 978-0-314-06339-7.
^ C. Michael Hogan. 2010. Calcium. eds. A. Jorgensen, C. Cleveland. Encyclopedia of Earth. National Council for Science and the Environment.
^ DOE (1994). "5". In A.G. Dickson & C. Goyet. Handbook of methods for the analysis of the various parameters of the carbon dioxide system in sea water. 2. ORNL/CDIAC-74. http://cdiac.esd.ornl.gov/ftp/cdiac74/chapter5.pdf.
^ Pinet 1996, p. 133
^ "Ask A Scientist". Biology Archive. http://www.newton.dep.anl.gov/askasci/bio99/bio99416.htm.
^ "Shipboard Medicine". http://www.bordeninstitute.army.mil/published_volumes/harshEnv2/HE2ch29.pdf. Retrieved 17 October 2010.
^ Etzion and Yagil; Yagil, R (1987;86(1)). "Metabolic effects in rats drinking increasing concentrations of seawater.". Comp Biochem Physiol A. 86 (1): 49–55. doi:10.1016/0300-9629(87)90275-1. PMID 2881655.
^ King, Dean (2004). Skeletons on the Zahara: a true story of survival. New York: Back Bay Books. p. 74. ISBN 978-0-316-15935-7.
^ Rippon, Commander P.M., RN (1998). The evolution of engineering in the Royal Navy. Vol 1: 1827-1939. Spellmount. pp. 78–79. ISBN 0-946771-55-3.

External links

Tables and software for thermophysical properties of seawater, MIT
Physical properties of sea water

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English Journal

The use of tetragonal star-like polyaniline nanostructures for efficient solid phase extraction and trace detection of Pb(II) and Cu(II) in agricultural products, sea foods, and water samples.

Behbahani M1, Bide Y1, Salarian M1, Niknezhad M1, Bagheri S2, Bagheri A3, Nabid MR4.Author information 1Department of Chemistry, Shahid Beheshti University, Evin, Tehran, Iran.2Department of Chemistry, Islamic Azad University, North Tehran Branch, Tehran, Iran.3Department of Chemistry, Shahid Beheshti University, Evin, Tehran, Iran. Electronic address: me-bagheri@sbu.ac.ir.4Department of Chemistry, Shahid Beheshti University, Evin, Tehran, Iran. Electronic address: m-nabid@sbu.ac.ir.AbstractDue to importance of trace analysis of lead and copper ions because of their toxicity, in this paper, for the first time a unique tetragonal star-like morphology of polyaniline was applied as a efficient solid phase for selective trace separation of copper and lead at optimum experimental conditions in shrimp, fish and water samples. Due to the unique star like nanostructure of synthesized sorbent, the tendency of the sorbent toward selective extraction of lead and copper ion in the optimised pH is very interesting. The prepared polymeric resin displayed good figures of merits with analytical calibration curve ranging from 1 to 120μgL(-1) for copper and 2 to 100μgL(-1) for lead ions with limits of detection of 0.4μgL(-1) for copper and 0.9μgL(-1) for lead, adsorption capacities of 84 and 110mgg(-1) for copper and lead ions, respectively, extraction efficiency of greater than 96%, and relative standard deviation (RSD) of less than 4% for eight separate column experiments in determination of 5.0μg of lead and copper. The obtained data for adsorption capacity of the sorbent shows the high tendency of the sorbent toward the mentioned ions in this nanostructure form. Finally, this sorbent can be used as a simple, rapid, reliable, selective and sensitive method for determination of trace levels of Cu(II) and Pb(II).
Food chemistry.Food Chem.2014 Sep 1;158:14-9. doi: 10.1016/j.foodchem.2014.02.110. Epub 2014 Mar 1.
Due to importance of trace analysis of lead and copper ions because of their toxicity, in this paper, for the first time a unique tetragonal star-like morphology of polyaniline was applied as a efficient solid phase for selective trace separation of copper and lead at optimum experimental conditions
PMID 24731308

Effect of experimental parameters in the pressurized solvent extraction of polyphenolic compounds from white grape marc.

Alvarez-Casas M1, García-Jares C1, Llompart M1, Lores M2.Author information 1Department of Analytical Chemistry, Nutrition and Food Science, Faculty of Chemistry, University of Santiago de Compostela, Avda. das Ciencias, s/n, 15782 Santiago de Compostela, Spain.2Department of Analytical Chemistry, Nutrition and Food Science, Faculty of Chemistry, University of Santiago de Compostela, Avda. das Ciencias, s/n, 15782 Santiago de Compostela, Spain. Electronic address: marta.lores@usc.es.AbstractA method based on pressurized solvent extraction (PSE) to determine main polyphenolic compounds in the grape marc obtained as a byproduct of the white winemaking process has been developed. As response variables in the optimisation process include main individual polyphenols, as well as spectrophotometric indexes. The optimised PSE procedure implies the use of 1g of sample, without preliminary clean-up step, sea sand as dispersant, temperature of 105°C, methanol (63%) in water as solvent, and 5min of extraction time (2 static cycles). The performance of the proposed method has been assessed in terms of recovery (91-105%), linearity (R(2)>0.995) and precision. The applicability of the method was demonstrated by the analysis of bagasse samples collected from 12 wineries located in Galicia (NW Spain). Data of the in vitro antioxidant activities of the PSE extracts are also discussed.
Food chemistry.Food Chem.2014 Aug 15;157:524-32. doi: 10.1016/j.foodchem.2014.02.078. Epub 2014 Feb 26.
A method based on pressurized solvent extraction (PSE) to determine main polyphenolic compounds in the grape marc obtained as a byproduct of the white winemaking process has been developed. As response variables in the optimisation process include main individual polyphenols, as well as spectrophoto
PMID 24679814

Assessment of ²¹⁰Po in Italian diet.

Meli MA1, Desideri D2, Roselli C1, Feduzi L1.Author information 1Biomolecular Sciences Department, University of Urbino, P.zza Rinascimento 6, 61029 Urbino, Italy.2Biomolecular Sciences Department, University of Urbino, P.zza Rinascimento 6, 61029 Urbino, Italy. Electronic address: donatella.desideri@uniurb.it.AbstractThis research was dedicated to the study, in the Italian daily diet, of the background activity concentration of (210)Po, a radionuclide with a high radiotoxicity. (210)Po was determined by alpha spectrometry. For food products of vegetable origin, the (210)Po activity concentration follows the trend: leafy vegetable>flour>rice>fruits>pasta>other vegetables>fruit vegetable; for those of animal origin: eggs>cheese>milk. The (210)Po activity concentration was also compared with that found by the same authors in meat, sea food, water and beverages in a previous study. The committed effective doses to individuals of three population groups (infants, children and adults) were 379, 222 and 151 μSv y(-1), respectively. The intake of foods of marine origin contributed about 67% of the total dose due to (210)Po ingestion. The effective dose, from (210)Po ingested by total diet, accounts for only 5-12% of the natural radiation exposure in Italy.
Food chemistry.Food Chem.2014 Jul 15;155:87-90. doi: 10.1016/j.foodchem.2014.01.049. Epub 2014 Jan 25.
This research was dedicated to the study, in the Italian daily diet, of the background activity concentration of (210)Po, a radionuclide with a high radiotoxicity. (210)Po was determined by alpha spectrometry. For food products of vegetable origin, the (210)Po activity concentration follows the tren
PMID 24594158