•Excess density
required to sink (Smayda, 1970)
•Diatoms sink
readily (compared to picoplankton)
•Recently, that CaCO3 is necessary
to sink deeply
–Sinking SiO2 carries 2.6 % by weight Org. C. while CaCO3 carries 7 % (Klaas and Archer, in prep.)
–SiO2 sinks more
slowly than CaCO3 (Berelson)
–SiO2 remineralizes
more shallowly than CaCO3
– (ZSiO2 ~1000 m vs. ZCaCO3 ~2500 m)