Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Sea Water shopping experience:
1. Compare - without doubt the biggest advantage that the Sea Water offers shoppers today is the ability to compare thousands of Sea Water at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.
2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about
3. Testimonials - don't know anybody that has bought a Sea Water? Wrong! If the Sea Water is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.
4. Questions - Got a question about Sea Water then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....
5. Reputation - Never heard of the company selling Sea Water? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Sea Water and build up a picture of their reputation for sales, returns, customer service, delivery etc.
6. Returns - still worried that even after all of the above your Sea Water wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.
7. Feedback - happy with your Sea Water then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.
8. Security - check for the yellow padlock on the Sea Water site before you buy, and the s after http:/ /i.e. https:// = a secure site
9. Contact - got a question about Sea Water, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.
10. Payment - ready to pay for your Sea Water, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.
for the World Ocean. Data from the World Ocean Atlas 2001.. Taken from onboard the
SuperStar VirgoSeawater is water from a sea or ocean. On average, seawater in the world's oceans has a
salinity of ~3.5%, or 35 parts per thousand. This means that every 1 kg of seawater has approximately 35 grams of dissolved salts (mostly, but not entirely, the ions of sodium chloride: Na+, Cl-). The average density of seawater at the surface of the ocean is 1.025 gram/litre; seawater is denser than fresh water (which reaches a maximum density of 1.000 g/mL at a temperature of 4°C) because of the added weight of the salts and electrostriction.http://duedall.fit.edu/ocn1010eng/jan27sp.htm
Salinity
{| class="wikitable" style="float: left; margin: 1em 1em 1em 1em;"|+ Seawater composition (by mass)|-!Element!Percent!Element!Percent|-|Oxygen|0.091|-|[Hydrogen|0.04|-|[Chlorine|0.04|-|[Sodium|0.0067|-|[Magnesium|0.0028|}
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 (meteorology) and river inflow, and confined circulation result in the formation of unusually salty seawater. The salinity in isolated seas and salt-water lakes (for example, the
Dead Sea) can be considerably greater.
The
density of surface seawater ranges from about 1020 to 1029 kg·m-3, depending on the temperature and salinity. Deep in the ocean, under high pressure, seawater can reach a density of 1050 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 1500 m·s-1, and varies with water temperature and pressure.
Compositional differences from fresh water
Seawater is more enriched in dissolved
ions of all types than fresh water.http://www.waterencyclopedia.com/Mi-Oc/Ocean-Chemical-Processes.html Thomson Gale, "Ocean Chemical Processes". Retrieved 12/2/06. However, the ratios of various solutes differ dramatically. For instance, although seawater is ~2.8 times more enriched with
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 constitute 48% of river water solutes, but only 0.41% of all seawater ions.Paul R. Pinet,
Invitation to Oceanography, (St. Paul: West Publishing Company, 1996), pp. 126, 134-135 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 out much more quickly.
Geochemical explanations
{| class="wikitable" style="float: right; margin: 0 0 1em 1em;"|+
Total Molal Composition of Seawater (Salinity = 35)http://cdiac.esd.ornl.gov/ftp/cdiac74/chapter5.pdf |-! Component !! Concentration (mol/kg)|-| Water (molecule) || 53.6|-| Chloride || 0.546|-| Sodium
|| 0.469|-| Magnesium || 0.0528|-| sulfate || 0.0282|-| Calcium || 0.0103|-| Potassium
|| 0.0102|-| Total inorganic carbon || 0.00206|-| Bromide || 0.000844|-| Total boron || 0.000416|-| Strontium || 0.000091|-| Fluoride || 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, having been leached out of the ground by rainfall runoff. Upon reaching the ocean, these salts would be retained and concentrated as the process of evaporation (see
Hydrologic cycle) removed the water. Halley noted that of the small number of lakes in the world without ocean outlets (such as the Dead Sea and the
Caspian Sea, see endorheic), most have high salt content. Halley termed this process "continental weathering".
Halley's theory is partly correct. In addition,
sodium was leached out of the ocean floor when the oceans first formed. The presence of the other dominant ion of salt, 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 basaltsPinet, 133. Since the ocean's creation, sodium is no longer leached out of the ocean floor, but instead is captured in sedimentary layers covering the bed of the ocean. One theory is that plate tectonics result in salt being forced under the continental land masses, where it is again slowly leached to the surface.
Potability
Even on a
ship or island in the middle of the ocean, there can be a "shortage of water" meaning, of course, a shortage of
fresh water. This is described famously by a line from
Samuel Taylor Coleridge's
The Rime of the Ancient Mariner:
"Water, water, every where
Nor any drop to drink."
Seawater can be turned into drinkable (potable) water by one of a number of desalination processes, or by diluting it with fresh water to reduce the salinity. Almost all large
ocean-going vessels create fresh water from seawater using vacuum evaporators, flash evaporators or by the use of reverse osmosis.
Otherwise,
seawater should not be drunk because of its high salt content. In the long run, more water must be expended to eliminate the salt (through
excretion in urine) than the amount of water that is gained from drinking the seawater itself. Ask A Scientist - Biology Archive http://www.newton.dep.anl.gov/askasci/bio99/bio99416.htm
The effect of seawater intake has been studied in laboratory setting in rats. (Etzion and Yagil; Metabolic effects in rats drinking increasing concentrations of sea-water. Comp Biochem Physiol A. 1987;86(1):49-55.)
Drinking seawater
Accidentally consuming small quantities of seawater is not harmful. However some people cling to a persistent and incorrect belief that humans can survive at sea by drinking only seawater. This misconception probably originated from questionable reports claiming that the French physician Alain Bombard survived an ocean crossing using only seawater and other provisions harvested from the ocean.
The amount of sodium chloride in human blood and in urine is always kept within a very narrow range of 9 g per L (0.9% by weight). Drinking seawater (which contains about 3.5% ions of dissolved sodium chloride) temporarily increases the concentration of sodium chloride in the blood, so the only way to excrete the excess sodium chloride in the urine is by sacrificing internal water from cells. The cells eventually give so much water to try to dilute the salt that they die from dehydration, quickly followed by organs and eventually the organism.
Survival manuals consistently advise against drinking seawater. For example, the book "Medical Aspects of Harsh Environments" (Chapter 29 - Shipboard Medicine) presents a summary of 163 life raft voyages. The risk of death was 39% for those who drank seawater, compared to only 3% for those who did not drink seawater.
See also
References
for the
World Ocean. Data from the
World Ocean Atlas 2001.. Taken from onboard the
SuperStar VirgoSeawater is water from a
sea or ocean. On average, seawater in the world's oceans has a salinity of ~3.5%, or 35 parts per thousand. This means that every 1
kg of seawater has approximately 35 grams of dissolved salts (mostly, but not entirely, the ions of
sodium chloride: Na+, Cl-). The average density of seawater at the surface of the ocean is 1.025
gram/litre; seawater is denser than
fresh water (which reaches a maximum density of 1.000 g/mL at a temperature of 4°C) because of the added weight of the salts and
electrostriction.http://duedall.fit.edu/ocn1010eng/jan27sp.htm
Salinity
{| class="wikitable" style="float: left; margin: 1em 1em 1em 1em;"|+ Seawater composition (by mass)|-!Element!Percent!Element!Percent|-|Oxygen|0.091|-|[Hydrogen|0.04|-|[Chlorine|0.04|-|[Sodium|0.0067|-|[Magnesium|0.0028|}
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 (meteorology) and river inflow, and confined circulation result in the formation of unusually salty seawater. The salinity in isolated seas and salt-water lakes (for example, the
Dead Sea) can be considerably greater.
The density of surface seawater ranges from about 1020 to 1029 kg·m-3, depending on the temperature and salinity. Deep in the ocean, under high pressure, seawater can reach a density of 1050 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 1500 m·s-1, and varies with water temperature and pressure.
Compositional differences from fresh water
Seawater is more enriched in dissolved ions of all types than fresh water.http://www.waterencyclopedia.com/Mi-Oc/Ocean-Chemical-Processes.html Thomson Gale, "Ocean Chemical Processes". Retrieved 12/2/06. However, the ratios of various solutes differ dramatically. For instance, although seawater is ~2.8 times more enriched with
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 constitute 48% of river water solutes, but only 0.41% of all seawater ions.Paul R. Pinet,
Invitation to Oceanography, (St. Paul: West Publishing Company, 1996), pp. 126, 134-135 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 out much more quickly.
Geochemical explanations
{| class="wikitable" style="float: right; margin: 0 0 1em 1em;"|+
Total Molal Composition of Seawater (Salinity = 35)http://cdiac.esd.ornl.gov/ftp/cdiac74/chapter5.pdf |-! Component !! Concentration (mol/kg)|-| Water (molecule)
|| 53.6|-| Chloride || 0.546|-| Sodium
|| 0.469|-| Magnesium
|| 0.0528|-| sulfate || 0.0282|-| Calcium
|| 0.0103|-| Potassium || 0.0102|-| Total inorganic carbon || 0.00206|-| Bromide || 0.000844|-| Total boron
|| 0.000416|-| Strontium || 0.000091|-| Fluoride
|| 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, having been leached out of the ground by rainfall runoff. Upon reaching the ocean, these salts would be retained and concentrated as the process of evaporation (see Hydrologic cycle) removed the water. Halley noted that of the small number of lakes in the world without ocean outlets (such as the
Dead Sea and the
Caspian Sea, see endorheic), most have high salt content. Halley termed this process "continental weathering".
Halley's theory is partly correct. In addition, sodium was leached out of the ocean floor when the oceans first formed. The presence of the other dominant ion of salt, 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 basaltsPinet, 133. Since the ocean's creation, sodium is no longer leached out of the ocean floor, but instead is captured in sedimentary layers covering the bed of the ocean. One theory is that plate tectonics result in salt being forced under the continental land masses, where it is again slowly leached to the surface.
Potability
Even on a
ship or island in the middle of the ocean, there can be a "shortage of water" meaning, of course, a shortage of fresh water. This is described famously by a line from
Samuel Taylor Coleridge's
The Rime of the Ancient Mariner:
"Water, water, every where
Nor any drop to drink."
Seawater can be turned into drinkable (potable) water by one of a number of desalination processes, or by diluting it with fresh water to reduce the salinity. Almost all large ocean-going vessels create fresh water from seawater using vacuum evaporators, flash evaporators or by the use of reverse osmosis.
Otherwise,
seawater should not be drunk because of its high salt content. In the long run, more water must be expended to eliminate the salt (through
excretion in
urine) than the amount of water that is gained from drinking the seawater itself. Ask A Scientist - Biology Archive http://www.newton.dep.anl.gov/askasci/bio99/bio99416.htm
The effect of seawater intake has been studied in laboratory setting in rats. (Etzion and Yagil; Metabolic effects in rats drinking increasing concentrations of sea-water. Comp Biochem Physiol A. 1987;86(1):49-55.)
Drinking seawater
Accidentally consuming small quantities of seawater is not harmful. However some people cling to a persistent and incorrect belief that humans can survive at sea by drinking only seawater. This misconception probably originated from questionable reports claiming that the French physician
Alain Bombard survived an ocean crossing using only seawater and other provisions harvested from the ocean.
The amount of sodium chloride in human blood and in urine is always kept within a very narrow range of 9 g per L (0.9% by weight). Drinking seawater (which contains about 3.5% ions of dissolved sodium chloride) temporarily increases the concentration of sodium chloride in the blood, so the only way to excrete the excess sodium chloride in the urine is by sacrificing internal water from cells. The cells eventually give so much water to try to dilute the salt that they die from dehydration, quickly followed by organs and eventually the organism.
Survival manuals consistently advise against drinking seawater. For example, the book "Medical Aspects of Harsh Environments" (Chapter 29 - Shipboard Medicine) presents a summary of 163
life raft voyages. The risk of death was 39% for those who drank seawater, compared to only 3% for those who did not drink seawater.
See also
References
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