American Geophysical Union Become an AGU Member
Subscribe to AGU Journals		 AGU Home AGU Publications

Read Full Article (file size: 302058 bytes)    Cited by

GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L07608, doi:10.1029/2008GL033294, 2008

The continental margin is a key source of iron to the HNLC North Pacific Ocean

Phoebe J. Lam

Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA


James K. B. Bishop

Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
Department of Earth and Planetary Science, University of California, Berkeley, California, USA


Abstract

Here we show that labile particulate iron and manganese concentrations in the upper 500 m of the Western Subarctic Pacific, an iron-limited High Nutrient Low Chlorophyll (HNLC) region, have prominent subsurface maxima between 100–200 m, reaching 3 nM and 600 pM, respectively. The subsurface concentration maxima in particulate Fe are characterized by a more reduced oxidation state, suggesting a source from primary volcagenic minerals such as from the Kuril/Kamchatka margin. The systematics of these profiles suggest a consistently strong lateral advection of labile Mn and Fe from redox-mobilized labile sources at the continental shelf supplemented by a more variable source of Fe from the upper continental slope. This subsurface supply of iron from the continental margin is shallow enough to be accessible to the surface through winter upwelling and vertical mixing, and is likely a key source of bioavailable Fe to the HNLC North Pacific.

Received 14 January 2008; accepted 4 March 2008; published 9 April 2008.

Keywords: iron; continental margin; HNLC.

Index Terms: 4875 Oceanography: Biological and Chemical: Trace elements (0489); 3002 Marine Geology and Geophysics: Continental shelf and slope processes (4219); 4808 Oceanography: Biological and Chemical: Chemical tracers; 1050 Geochemistry: Marine geochemistry (4835, 4845, 4850).

Read Full Article (file size: 302058 bytes)    Cited by

Citation: Lam, P. J., and J. K. B. Bishop (2008), The continental margin is a key source of iron to the HNLC North Pacific Ocean, Geophys. Res. Lett., 35, L07608, doi:10.1029/2008GL033294.