Some areas of the ocean are saltier than other but on average there are 35 grams of salt per kilogram of seawater. The ocean contains about 1.4 sextillion kilograms of seawater. (Imagine the number 14 with 20 zeros after it). That’s equal to about
3.09 sextillion pounds of seawater. Therefore there’s about 50 quintillion kilograms (the number 50 with 18 zeros after it) of salt in the ocean. There are many factors that make the ocean salty. Sea salt is mostly made up of a compound called sodium chloride (regular table salt) but it also has other minerals such as magnesium, calcium, and potassium that have dissolved in seawater. Salt has accumulated in the ocean over a very long period of time from rivers, the seabed, and vents from
deep in the earth that contain these same dissolved minerals. The processes that are adding salt to the ocean are very slow. They happen over millions of years and that keeps the salt content of the ocean relatively constant. Over periods of decades or centuries, new salt is added to the ocean in quantities that are far smaller than the amount already there. Scripps Institution of Oceanography at UC San Diego scientists and their colleagues are measuring the global distribution of
ocean salinity to better understand how it changes with climate over seasons and years. Processes that affect saltiness include excesses of rain, which can dilute the ocean and lower its salinity and evaporation, which can have the opposite effect and make it saltier. Melting or freezing of ice can make water less salty or more salty. Finally, ocean currents can carry more or less salty waters to other regions of the world altering the salinity in those places. —Dean Roemmich,
physical oceanographer, Integrative Oceanography Division Sign Up For Explorations Nowexplorations now is the free award-winning digital science magazine from Scripps Institution of Oceanography. Join subscribers from around the world and keep up on our cutting-edge research. If there is one thing that just about everyone knows about the ocean is that it is salty. The two most common elements in seawater, after oxygen and hydrogen, are sodiumsodium and chloride. Sodium and chloride combine to form what we know as table salt. Seawater salinity is expressed as a ratio of salt (in grams) to a liter of water. In seawater, there are typically close to 35 grams of dissolved salts in each liter. It is written as 35‰. The normal range of ocean salinity ranges between 33-37 grams per liter (33‰ - 37‰). But as in weather, where there are areas of high and low pressure, there are areas of high and low salinity. Of the five ocean basins, the Atlantic Ocean is the saltiest. On average, there is a distinct decrease in salinity near the equator and at both poles, although for different reasons. Near the equator, the tropics receive the most rain on a consistent basis. As a result, the freshwater falling into the ocean helps decrease the salinity of the surface water in that region. As one moves toward the poles, the region of rain decreases and with less rain and more sunshine, evaporation increases. In comparison freshwater, in the form of water vapor, moves from the ocean to the atmosphere through evaporation causing the higher salinity. Toward the poles, freshwater from melting ice decreases the surface salinity once again. The saltiest locations in the ocean are the regions where evaporation is highest or in large bodies of water where there is no outlet into the ocean. The saltiest ocean water is in the Red Sea and in the Persian Gulf region (around 40‰) due to very high evaporation and little freshwater inflow. So just how do the two compare? If you take one cubic foot of seawater and evaporate it you would have about 2.2 pounds of salt left behind. If you do the same with a cubic foot of water from one of the Great Lakes of North America only about 0.01 pounds of salt or about one-sixth of an ounce of salt would be left behind. Therefore, the sea is about 220 times saltier than our primary freshwater resources. Visualization of how much salt is actually contained in sea water. When preparing “sea water samples” for class, it is always astonishing to me how much salt I have to add for normal open-ocean salinities. Time and time again it looks like it should be way too much, but then when tasting it, it tastes salty, but like the ocean and not like brine.  A teaspoon full of salt corresponds to approximately 5 grams. That means that for typical open-ocean salinities, you have to add 7 teaspoons full of salt to a liter of water. Since it is still astonishing to us, Pierre and I thought, it would probably be a good thing to show to our students. 0.18 teaspoon full of salt corresponds to only 1 gram of salt (averaged over several non-scientific internet sources, but well within the measurement error of my kitchen scales [and yes, I know the trick of measuring the weight of several spoons and then dividing by the number, but thanks!]). What I want to do in the lecture is have the students estimate how much salt they need for a 35 psu liter of water. And not estimate by weighing (because I want each of the students to be able to touch the salt, but at the same time don’t want salt all over the lecture theatre), but visually estimate. 10 grams of salt in a little plastic jar. The little jar in the picture above contains 10 grams of salt. So in order to have students estimate how much salt they would need for a liter of 35psu water, we filled 12 of those little jars with 10 grams each and handed them to the students. Obviously we didn’t tell the students how much salt was contained in a jar! 12 x 10 grams of salt. It does look like a lot more, doesn’t it? Knowing that there are 10 grams of salt in each of the jars, it is pretty obvious that we need three and a half of those little jars for 35 grams of salt. When we did this in the lecture on Tuesday – and again, the students were not told how much salt was in one jar! -, the first person who answered guessed “four”. And then someone actually said “three and a half”. Oh well, lucky guess or great skill? I was hoping for answers like “maybe one of those jars”, because that would be closer to my own intuition. I guess next time I’ll be framing it differently. Maybe use something with one liter volume and put 35 grams in it? Or ask them to tell me in teaspoons? Does anyone have a good idea that they would like to share with me? How much salt is in every gallon of seawater?A little math was in order. Seawater is about 3.5 percent salt by weight, which means a gallon of water (eight pounds) should yield about 4.5 ounces of salt.
How much salt is in 1 kg of sea water?On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, or 0.600 M) This means that every kilogram (roughly one litre by volume) of seawater has approximately 35 grams (1.2 oz) of dissolved salts.
How much salt is in 5 gallons of seawater?With five gallons of seawater, you can produce 3.5 pounds of salt.
How many teaspoons of salt are in ocean water?The main one is sodium chloride, often just called salt. Most seawater has about 35 g (7 teaspoons) of salt in every 1,000 g (about a litre) of water.
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How much salt is in sea water
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