Net oxygen consumption
Assume that the initial oxygen concentration of a water mass when it existed at the surface was [O2]0, and that the water mass has moved to a depth of 3000 m. We then conducted oceanographic observations and sampled water at a depth of 3000 m to measure oxygen concentrations [O2 3000 m]. The amount of oxygen consumed by respiration during the movement of that water mass to 3000m is determined by the formula [O2 consumed by respiration] = [O2]0 - [O2 3000m].
Once the atmospheric oxygen concentration (a constant value) and water temperature are determined, [O2]0 can be calculated.
【Amount of oxygen consumed by respiration】
Let us estimate the amount of oxygen (ΔO2) consumed by respiration between time t = 0 and t = T.
ΔO2 = 【O2】t=0 －【O2】t=T
【O2】t is the oxygen concentration at time t.
In the actual ocean, How should we define. How should we define 【O2】t=0 and 【O2】t=T?
One should be able to take exactly the same water samples at different times and measure the oxygen concentration. At "locations where the water masses are guaranteed to remain", we take our time to observe. In the case of Funka-Bay in Hokkaido, we know from experience that the water stays at a certain depth at a certain time of year, so we can plan such an observation.
