Dissolved iron distribution in the tropical and sub tropical

Abstract

Abstract. Dissolved iron (DFe) distributions (<0.2µm) were determined in the upper water column (0–400 m) of the south eastern tropical and subtropical Pacific, in October– November 2004. Data were collected along a transect ex-tending from the Marquesas Islands to the Chilean coast with most of the stations located in the south Pacific gyre. The concentrations of DFe presented large variability with highest values observed at both extremities of the transect. In the Chilean upwelling, DFe concentrations ranged be-tween 1.2–3.9 nM. These high values result from inputs from the continental margin and are likely maintained by anoxic conditions in the water corresponding to the Oxygen Min-imum Zone (OMZ). In subsurface waters near the Marque-sas, that were also associated with the extension of the OMZ, DFe concentrations varied between 0.15–0.41 nM. Vertica