Ocean dissolved gases — Science Learning Hub
Seawater has many different gases dissolved in it, especially nitrogen, oxygen and carbon dioxide.
It exchanges these gases with the atmosphere to keep a balance between the ocean and the atmosphere. This exchange is helped by the mixing of the surface by wind and waves.
Gases and life
Dissolved oxygen and carbon dioxide are vital for marine life.
Marine plants use dissolved carbon dioxide, sunlight and water to make carbohydrates through the process of photosynthesis.
This process releases oxygen into the water.
All marine organisms use oxygen for respiration, which releases energy from carbohydrates and has carbon dioxide and water as byproducts.
Marine animals with gills, such as fish, use these organs to extract oxygen from the seawater.
Variation in dissolved gases
Some of the properties of seawater affect how much gas can be dissolved in it:
- Cold water holds more gas than warm water. You will have seen this with bottles of fizzy drink, which are basically carbon dioxide in water. A warm fizzy drink cannot hold its gas, so as soon as you open a bottle of it, the carbon dioxide leaves the water in a big spray of bubbles. It is less messy to open a cold bottle of fizzy drink.
- Seawater with low salinity holds more gas than high salinity water.
- Deep water, which has a high pressure, holds more gas than shallow water.
The use and creation of dissolved gases by living things can over-ride the effect of these properties.
For example, warm water with lots of plankton in it can hold more carbon dioxide than cold water with few living things in it.
Carbon dioxide
Carbon dioxide is one of the most important gases that dissolve in the ocean.
Some of it stays as dissolved gas, but most reacts with the water to form carbonic acid or reacts with carbonates already in the water to form bicarbonates.
This removes dissolved carbon dioxide from the water.
Many plants and animals use the bicarbonate to form calcium carbonate shells.
When these organisms die, some of the bicarbonate is returned to the water, but a lot of it settles down to the sea bed.
This process locks up, for long periods of time, carbon that originated in carbon dioxide in the atmosphere.
If the ocean and atmosphere stayed the same, there would be a balance between the concentrations of carbon dioxide in each, but carbon dioxide levels in the atmosphere are rising, so more of the gas is dissolving in the ocean.
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Tom O
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“If the ocean and atmosphere stayed the same, there would be a balance between the concentrations of carbon dioxide in each, but carbon dioxide levels in the atmosphere are rising, so more of the gas is dissolving in the ocean.”
I always love these articles that “imply” one thing or another. It does say that warm water holds less CO2, but then tries to pretend that if there is more plankton, well, it won’t be off gassing that CO2.
The whole article thus implies that something is causing the CO2 in the atmosphere to rise, and we all know what that is, right? Probably more people breathing, that is why we have the depopulation shot. Since we wouldn’t give up carbon fuels, then they get rid of us instead.
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Artelia
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The price of heating, means we will be dying off and giving up our use of CO2.
CH4 releases little CO2, mostly water.
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