Question

From Wikipedia: In the deep ocean, marine snow is a continuous shower of mostly organic detritus falling from the upper layers of the water column. It is a significant means of exporting energy from the light-rich photic zone to the aphotic zone below. The term was first coined by the explorer William Beebe as he observed it from his bathysphere. As the origin of marine snow lies in activities within the productive photic zone, the prevalence of marine snow changes with seasonal fluctuations in photosynthetic activity and ocean currents. Marine snow can be an important food source for organisms living in the aphotic zone, particularly for organisms which live very deep in the water column. One component of marine snow, diatoms, range in size from about 10–150 µm. I found an article in the Journal of Plankton Research (van Ierland and Peperzak 1983) that reported diatom mass density to be around 1.1 g cm -3.

a) Calculate how long it would take for diatoms to settle to the bottom of the Challenger Deep. That is, about how old was the marine snow that James Cameron saw when he looked around down there? (Don’t forget to consider buoyancy).

b) Based on your calculation in part a), select a reasonable velocity for oceanic currents and make an estimate of the distance to the origin of the snow that Cameron observed.

Answer 1