Sinking flux, particulate

Iron and manganese are initially supplied to the sediments as a component of the sinking flux of POM and particifiate oxyhydroxides. Remineralization of the POM releases iron and manganese to the pore waters. In the presence of O2, the solubilized metals are oxidized and precipitate as oxyhydroxides, thereby increasing the inorganic particifiate phase in the oxic layer. Continuing sedimentation eventually carries this particulate Mn and Fe below the oxic zone. 

Significance of vertical flux as a sink for particulate DMSP... 

Figure 1 A schematic representation of the ocean reservoir. The source and sink fluxes are designated as g and n, referring to gross and net fluxes, thereby indicating that interactions within the boundary regions can modify the mass transfer. Within seawater, the p d term signifies that substances can undergo particulate-dissolved interactions. However, it must be appreciated that several transportation and transformation processes might be operative (Adapted from Chester, 1990. )...

Zooplankton may reduce the sinking flux of biogenic particles in the ocean in two ways. The first is by grazing upon particles which reduces the total amount of particulate organic material (POM) in the water column and shifts its occurrence from large, fast-sinking aggregates to smaller fecal pellets which constitute only a minor... 

Figure 12 Nitrogen isotopic values of suspended particulate matter and sinking particles (as collected by sediment traps) in the subtropical North Atlantic Ocean near BATS (31° 50 N, 64° 10 W see Figure 6). The profiles of suspended PN show the representative depth gradient in <5 N, with lower iS N in the surface ocean than at depth. The <5 N of the sinking flux shows a decrease with depth, which has also been observed in other regions. Reprinted from Altabet MA, Deuser WG, Honjo S, and Stienen C (1991) Seasonal and depth-related changes in the source of sinking particles In the North Atlantic. Nature 354 136-139.

Buesseler et al. (1992b) proposed a method to circumvent these difficulties in comparing residence times. They argued that the deficiency in total " Th with respect to indicates a flux of " Th in association with particles sinking out of the euphotic zone. If the POC (or particulate organic nitrogen, PON)/ Th ratio of these sinking particles is known, a POC (or PON) flux can be calculated as ... 

The flux J of element carried downwards by the sinking particles (the rain ) can be estimated by comparison with the flux of dissolved element. We write that, at steady-state, the sum of dissolved and particulate fluxes remains constant, i.e., for two depths Zj and z2... 

The vertical distribution of biolimiting elements is characterized by deep-water enrichments and surface-water depletions. As described above, this vertical segregation is caused by the remineralization of biogenic particles in the deep sea. Not all particulate matter that sinks into the deep zone is remineralized. Some survives to become buried in the sediments. How much of the biogenic particle flux escapes from surfece waters How much of this particle flux is remineralized in the deep zone How much is lost from the ocean by burial in the sediments What effect does this have on the concentrations of the biolimiting elements ... 

The rain rate of BSi is dependent on (1) the rate of its production by marine organisms, (2) shell dissolution rates, and (3) the time required for a shell to reach the seafloor. High rates of production by siliceous plankton ensure a large supply of opal to the water column. The fraction reaching the seafloor is largest when transit times are shortest. Thus, shells that sink fastest will be preferentially preserved and a greater fraction of the particulate silica flux reaches sediments that lie in shallow waters. 

Bloesch, J., and M. Sturm, Settling flux and sinking velocities of particulate phosphorus (PP) and particulate organic carbon (POC) in Lake Zug, Switzerland . In Sediments and Water Interactions, P. G. Sly, Ed., Springer, New York, 1986, pp. 481-490. 

Benitez-Nelson, C. R., Madden, L. P. O., Styles, R. M., Thunell, R. C., and Astor, Y. (2007). Inorganic and organic sinking particulate phosphorus fluxes across the oxic/anoxic water column of Cariaco Basin, Venezuela. Mar. Chem. 105,90-100. 

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