ocean and oxygen questions

Question

1.  The upper layer of the ocean contains an abundance of microorganisms that carry out photosysthesis, such as  algae.  Why would this make the upper layer rich in oxygen?

 

2.  In general the amount of oxygen in the ocean decreases with depth.  Towars the bottom of the ocean, however, oxygen levels increase slightly.  Explain this slight increases in terms of the differing abilities of warm and cold water to dissolve oxygen.

 

3.  In view of the answer to #2, what might happen to the amount of oxygen dissolved in the upper layer of the ocean if the temperature of that layer increases significantly?

 

 

thanks

Answer 1

1.)Photosynthesis in  the presence of water has O₂ as a waste by product which can saturate the upper layer of a body of water. Excess will degas to the atmosphere.

 

2. Oxygen is an Henry's Law gas: the equilibrium concentration at a given temperature is directly proportional to the partial pressure in the gas phase and is generally a decreasing function of temperature. Colder temperatures and higher total pressures(near the bottom) will have higher dissolved O₂ concentrations due to the presence of air bubbles.

 

3.) The solubility is lower at higher temperatures so the total amount of O₂ dissolved would be less.

 

Jim