Fecal pellet

Carder KI, Steward RG, Betzer BR (1982) In situ holographic of the size and settling rates of oceanic particles. Journal of Geophysical Research 87 5681-5685 Cherry RD, Higgo JJW, Fowler SW (1978) Zooplankton fecal pellets and element residence times in the ocean. Nature 274 246-248... 

Table 32.12 Time Required to Transport Selected Radionuclides Added into Marine Waters at Surface out of the Upper Mixed Layer by Biological Transport (Processes include diurnal vertical migration, fecal pellets, and sinking of dead matter.)...

Marine copepods, 3 species May 6,1986 whole organism vs. fecal pellets ... 

Redfield (1934), who analyzed the major elemental content of many samples of mixed plankton (phytoplankton and zooplankton) caught in nets towed through the surface ocean. They compared the carbon, nitrogen, and phosphorus composition of these collections to concentration profiles of dissolved inorganic carbon (DIC), NOs, and P04 throughout the water column. This pioneering research demonstrated that these three elements are continually redistributed in the ocean by selective removal into plankton cells and their remains (i.e., fecal pellets), which are then efficiently respired as they sink through the marine water column. 

As mentioned above, most oils are buoyant in water. However, in areas with high levels of suspended sediment, petroleum constituents may be transported to the river, lake, or ocean floor through the process of sedimentation. Oil may adsorb to sediments and sink or be ingested by zooplankton and excreted in fecal pellets that may settle to the bottom. Oil stranded on shorehnes also may pick up sediments, float with the tide, and then sink. Most of this process occurs from about 2 to 7 days after the spill. 

Solids Organic Particulate Matter Inorganic Particulate Matter ng/L to mg/L ng/L to mg/L Plankton biomass, fecal pellets, molts, feeding nets Atmospheric dust, riverborne clay minerals, iron oxyhydroxides, micrometeorites... 

Other resolubilized trace metals precipitate as replacement ions in existing solids such as fecal pellets and bone. Examples of these fiassilized materials include barite, phosphorite, and glauconite. These precipitates contain small amounts of a variety of trace metals as well as other elements. As a result, their chemical composition is variable and their structure is usually amorphous, making it difficult to assign them an empirical formifia. 

Most of the mass transport to the seafloor is in the form of large and, hence, rapidly sinking particles. Most of these are biogenic in origin, such as fecal pellets, cast-off... 

Over longer time scales, clay minerals can undergo more extensive reactions. For example, fossilization of fecal pellets in contact with a mixture of clay minerals and iron oxides produces an iron- and potassium-rich, mixed-layer clay called glauconite. This mineral is a common component of continental shelf sediments. Another example of an authigenic reaction is called reverse weathering. In this process, clay minerals react with seawater or porewater via the following general scheme ... 

Three mechanisms have been proposed to explain how particulate metals could be transported within such sediments so as to support the growth of Fe-Mn nodules (1) anoxic microzones, (2) bioturbation, and (3) shifts in the depth of the redox boundary over time. Anoxic microzones are present within fecal pellets and the interiors of radiolarian shells where detrital POM is still present. Metals mobilized within these microzones should be able to diffuse through the sediments for substantial distances... 

Some green clay minerals occur as ovoids, probably having formed within fecal pellets or casts of forams. They also occur as films or stains on shells, sand grains, and phosphate nodules. They are finmd in highest density in sediments of the outer continental shelves and slopes where waters are shallow (20 to 700 m) and mildly suboxic. Slow sedimentation rates are necessary to prevent burial as green clays form at very slow rates. A notable example are the green muds found on the Blake Plateau. 

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