Is water at the bottom of the ocean oxygen deficient?

In summary, water at the bottom of the ocean is oxygen deficient relative to water at higher levels. It is denser at the 4 deg layer, and diffusion is one of the factors that decreases the oxygen concentration.
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MulderFBI
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Is water at the bottom of the ocean oxygen deficient? Compared to water at the higher levels.
 
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  • #2
MulderFBI said:
Is water at the bottom of the ocean oxygen deficient? Compared to water at the higher levels.
I am not entirely sure, but I think I've read somewhere that it is. Intuitively speaking, it does sound plausible. The only factor that may increase the oxygen concentration at lower level of ocean is water pressure. I think every other factors (such as lack of atmospheric contact, water temperature although it won't go below 4 deg, relative lack of plants, etc.) decreases the oxygen concentration at lower ocean level.
 
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Thank you, I wanted to verify that claim. One of the explanations I've found is that it's because water at the bottom is very dense (especially at the 4 deg layer). That density stops it from absorbing oxygen (and other gases) through for example diffusion or convection but I'm not sure it's true.
 
  • #4
MulderFBI said:
Thank you, I wanted to verify that claim. One of the explanations I've found is that it's because water at the bottom is very dense (especially at the 4 deg layer). That density stops it from absorbing oxygen (and other gases) through for example diffusion or convection but I'm not sure it's true.
I am not an expert, but I wouldn't be surprised if that was true.

EDIT: The density of water don't change that much, even comparing between sea level and bottom of the ocean. And at 4 deg layer, it remains pretty much the same. Nonetheless, diffusion indeed may be one of the biggest reason for the low oxygen concentration at low ocean depth.
 
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Why is that? I'm pretty sure water at 4deg is at the most dense point so I would say it is denser than on higher levels when temperature rises.
 
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MulderFBI said:
Why is that? I'm pretty sure water at 4deg is at the most dense point so I would say it is denser than on higher levels when temperature rises.
Well, I said "don't change that much", which means it still does change a little. It probably changes around 0.01 g/cm3 comparing sea level and the bottom of the ocean, if not, less. Density of sea water is around 1.025 - 1.027 at sea level. So a 1% difference (or less) is a minor difference to me.
 
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You are right the difference is not that big:
density_depth.jpg

"This is a simple density-depth ocean water profile. You can see density increases with increasing depth. The pycnocline are layers of water where the water density changes rapidly with depth. This density-depth profile is typical of what you might expect to find at a latitude of 30-40 degrees south.
Windows to the Universe original image"
 

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  • #8
Meromictic water, water that never intermixes with surface water is anoxic, promoting the growth of anaerobic bacteria - the kind of bacteria that were common on Earth prior to an oxygen atmosphere. This can happen in deep lakes, and is often found at the bottom of fjords. Hadalpelagic is the term more often used for ocean basin closed canyons
Discussion on lakes: https://en.wikipedia.org/wiki/Meromictic_lake

There is a whole lot more to this topic- dead zones and so on. This talks about O2 in the entire water column of the ocean.
http://www.fondriest.com/environmental-measurements/parameters/water-quality/dissolved-oxygen/

Is a great resource it has interesting discussions and graphics.
 
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  • #10
Thank you for great resources!
 

1. Why is there less oxygen at the bottom of the ocean?

The deeper you go in the ocean, the less oxygen there is. This is because oxygen is primarily produced at the surface through photosynthesis by phytoplankton and other marine plants. As water sinks to the bottom, it becomes more and more depleted of oxygen.

2. How is the oxygen level in the ocean measured?

Oxygen levels in the ocean are typically measured using a device called a dissolved oxygen sensor. This sensor measures the amount of oxygen dissolved in the water, which is a key indicator of the overall oxygen content in the ocean.

3. What happens to marine life in areas with low oxygen levels?

Marine life requires oxygen to survive, and in areas with low oxygen levels, many species may struggle to survive. Some species, such as fish, will swim to shallower waters with higher oxygen levels, while others may die off or experience stunted growth due to oxygen deficiency.

4. What causes oxygen deficiency in the ocean?

Oxygen deficiency in the ocean can be caused by a variety of factors, including high water temperatures, excess nutrient pollution, and changes in ocean currents. Climate change is also a major contributor, as warmer ocean temperatures can decrease the amount of dissolved oxygen in the water.

5. How does ocean oxygen deficiency affect the planet?

Ocean oxygen deficiency is a major concern for the health of our planet. It can lead to the death of marine life, disrupt marine ecosystems, and impact the ocean's ability to absorb carbon dioxide. This can have far-reaching effects on the global climate and the health of the planet as a whole.

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