How to apply Henry's law down the sea? Background: Henry's law states that:


  At a constant temperature, the amount of a given gas that dissolves in
  a given type and volume of liquid is directly proportional to the
  partial pressure of that gas in equilibrium with that liquid.


And mathematically:

$$S=k\times p_{\text{gas}}$$
where $S$ is solubility, $k$ is Henry's constant and $p$ is the partial pressure of the gas.

Question: I want to calculate the oxygen solubility down the sea. Is partial pressure the atmospheric one? If it is so, we have same solubility on all sea deepness, which is contradictory. What am I missing?



Edit

I know this law can be thought as depending on this equilibrium:

$$\ce{A {(g)} &lt;=&gt; A {(s)}}$$
What does it even mean to calculate or measure solubility of something down the sea?

Why, there is a precise and well-defined meaning, and it is hinged on equilibrium between the gas and the solution, which supposedly should be established at the said conditions. Our imaginary gas bubble, like everything else, must withstand the immense pressure of all those layers of water up above.

So no, the partial pressure is not just the atmospheric one.

Deep abyss of the seas is undersaturated in all gases, including oxygen, and that by a wide margin.