IS BURIAL VELOCITY A MASTER PARAMETER FOR BIOTURBATION

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.