Kinetic bottlenecks to respiratory exchange rates in the deep-sea – Part 1: Oxygen

[摘要] Ocean warming is now reducing dissolved oxygen concentrations, which can posechallenges to marine life. Oxygen limits are traditionally reported simply asa static concentration threshold with no temperature, pressure or flow ratedependency. Here we treat the oceanic oxygen supply potential forheterotrophic consumption as a dynamic molecular exchange problem analogousto familiar gas exchange processes at the sea surface. A combination of thepurely physico-chemical oceanic properties temperature, hydrostatic pressure,and oxygen concentration defines the ability of the ocean to provide theoxygen supply to the external surface of a respiratory membrane. This generaloceanic oxygen supply potential is modulated by further properties such asthe diffusive boundary layer thickness to define an upper limit to oxygensupply rates. While the true maximal oxygen uptake rate of any organism islimited by gas transport either across the respiratory interface of theorganism itself or across the diffusive boundary layer around an organism,controlled by physico-chemical oceanic properties, it can never be largerthan the latter. Here, we define and calculate quantities that describe thisupper limit to oxygen uptake posed by physico-chemical properties around anorganism and show examples of their oceanic profiles.

[学科分类] 地球化学与岩石