Iron in the western Pacific: a riverine or hydrothermal source for iron in the Equatorial Undercurrent?

The Iron Biogeochemical Cycle Past and Present

“…in the Ross Sea and in the sub-polar North Atlantic; Sedwick and DiTullio, 1997;Lavender et al, 2005). However velocities are much faster (up to 100 cm s -1 ) in the undercurrents studied by Mackey et al (2002). During transport in an oxic shuttle nanoparticulate ferrihydrite may dissolve to form aqueous Fe(III), or sink by becoming attached to sediment grains or scavenged by large aggregates.…”

“…The Equatorial and the New Guinea Coastal Undercurrents (Mackey et al, 2002) are also enriched in particulate plus aqueous iron (measured on filtered and acidified samples). These studies appear to capture the operation of a shelf-derived transport flux but how quickly does transport occur?…”

Iron isotopic fractionation during continental weathering

“…The flux of diagenetic Fe from marine sediments to the ocean may also be significant [41][42][43]. While it is known that Fe is reduced during burial in marine sedimentary columns [34], the escape of Fe from sediments into the overlying water column correlates with and is presumably controlled by the flux of organic carbon (C org ) to the sediments [43,44].…”

Sources and transport of dissolved iron and manganese along the continental margin of the Bay of Biscay

“…Laës et al: Sources of iron and manganese in the Bay of Biscay was suggested as the primary source of iron to the surface waters of the Equatorial upwelling zone in the Pacific (Coale et al, 1996;Mackey et al, 2002;Fitzwater et al, 2003) and the Antarctic polar front zone (de Baar et al, 1995;Loscher et al, 1997). Moreover dynamic processes occurring on the continental margins are capable of efficiently moving trace elements from deep to surface waters and to the interior of the ocean (Wells et al, 1999;Lacan and Jeandel, 2001;Mackey et al, 2002;Hoppema et al, 2003). Continental margins, through fluvial inputs, sediment remobilisation and hydrodynamic processes constitute a major source of trace metals for coastal and in some situations also open ocean waters.…”