Jickells T. D.

No Thumbnail Available
Last Name
Jickells
First Name
T. D.
ORCID

Filters

2007 1
1
1
Reset filters

Settings

Search Results

Now showing 1 - 1 of 1
  • Preprint
    Dissolved iron in the vicinity of the Crozet Islands, Southern Ocean
    ( 2007-04-26) Planquette, Helene ; Statham, Peter J. ; Fones, Gary R. ; Charette, Matthew A. ; Moore, C. Mark ; Salter, Ian ; Nedelec, Florence H. ; Taylor, Sarah L. ; French, M. ; Baker, Alexander R. ; Mahowald, Natalie M. ; Jickells, T. D.
    The annual phytoplankton bloom occurring north of the Crozet Plateau provides a rare opportunity to examine the hypothesis that natural iron fertilisation can alleviate HNLC conditions normally associated with the Southern Ocean. Therefore, during CROZEX, a large multidisciplinary study performed between November 2004 and January 2005, measurements of total dissolved iron (DFe, ≤ 0.2 μm) were made on seawater from around the islands and atmospheric iron deposition estimated from rain and aerosol samples. DFe concentrations were determined by flow injection analysis with N,N-dimethyl- pphenylenediamine dihydrochloride (DPD) catalytic spectrophotometric detection. DFe concentrations varied between 0.086 nM and 2.48 nM, with low values in surface waters. Enrichment of dissolved iron (>1 nM) at close proximity to the islands suggests that the plateau and the associated sediments are a source of iron. Waters further north also appear to be affected by this input of coastal and shelf origin, although dissolved iron concentrations decrease as a function of distance to the north of the plateau with a gradient of ~0.07 nM.km-1 at the time of sampling. Using lateral and vertical diffusion coefficients derived from Ra isotope profiles and also estimates of atmospheric inputs, it was then possible to estimate a DFe concentration of ~0.55 nM to the north of the islands prior to the bloom event, which is sufficient to initiate the bloom, the lateral island source being the largest component. A similar situation is observed for other Sub-Antarctic Islands such as Kerguelen, South Georgia, that supply dissolved iron to their surrounding waters, thus, enhancing chlorophyll concentrations.