Zooplankton fecal pellets and element residence times in the ocean.

CHERRY, R. D.; HIGGO, J. J. W.; FOWLER, S. W.

THE concept of oceanic residence time has been used widely in marine chemistry; element residence times1 range from 108 to <100yr, and provide a useful measure of the reactivity of an element in the ocean. The residence time of an element is defined as the average time an element spends in ocean water between introduction into the ocean and incorporation into the sediments. Between introduction and incorporation transport mechanisms must exist; a relationship between residence time and a property associated with a particular transport mechanism is, therefore, a logical possibility. A transport mechanism which has received increasing attention and which is discussed here involves zooplankton fecal pellets. These pellets sink fairly rapidly2-4, at rates ranging from 50 to ∼950 m per day, and they decompose relatively slowly. They seem to have the potential to reach the sea bottom in most areas, and have been identified in sedimentation traps3 placed at depth in the ocean; moreover, a model for particle settling in the equatorial Atlantic Ocean4 indicated that 99% of the vertical mass flux through 388 m is carried by fecal matter and fecal pellets. As far as specific elements are concerned, fecal pellets have been shown to be important in the vertical oceanic transport of zinc5, cerium6, polonium7 and plutonium8.

Nature, 1978, Vol 274, Issue 5668, p246

0028-0836

Academic Journal

10.1038/274246a0