The intensity of biological mixing in a marine sediment is widely beli
eved to be related to the flux of labile organic matter. At the same t
ime, this flux has been shown to be strongly correlated to the burial
velocity. One would then expect a significant correlation between biol
ogical mixing coefficient, D(B), and burial velocity, omega. A nonline
ar regression of existing data with a power law (Eqns. 2 and 3 of the
text) produces a statistically significant correlation. The statistica
l significance of the regression in no way implies causation and, in f
act, it accounts for only about 22% of the total variance in the datas
et, thus reducing its physical significance. A number of additional pr
ocesses contribute to the large observed variance, including timing of
mixing events, temporal and spatial heterogeneity, differences in tem
poral scales, sampling artifacts, and specific particle associations.
With due care, the D(B)-omega relationship may prove useful in definin
g the likely range of D(B) values in a particular environment. A simil
ar analysis of the tracer-identified surface mixed-depth shows that it
is essentially independent of burial velocity with a worldwide mean o
f 9.8 +/- 4.5 cm. Depth of mixing is probably more closely related to
the energetic costs of deep burrowing.