I don't think there is such a reference, because this is not generally true in the ocean. Microplankton might dominate in certain locations at certain times (and they could dominate export flux under bloom conditions), but generally speaking the phytoplankton is dominated (in terms of biomass and productivity) by pico- (0.2-2 µm) and nanoplankton (2 -20 µm). Here is one recent paper that provides a global overview of the size distribution. It is a model with attendant caveats, but agrees overall with the observations made in many parts of the global ocean.
Kostadinov, T. S., S. Milutinović, I. Marinov, and A. Cabré. 2016. Carbon-based phytoplankton size classes retrieved via ocean color estimates of the particle size distribution. Ocean Sci. 12: 561–575. doi:10.5194/os-12-561-2016