L11604 Ellwood.pdf (1020.95 kB)
Download fileWinter-time dissolved iron and nutrient distributions in the Subantarctic Zone from 40-52S; 155-160E
journal contribution
posted on 2023-05-18, 04:00 authored by Ellwood, MJ, Philip BoydPhilip Boyd, Sutton, PIn HNLC oceanic regions, iron (Fe) controls phytoplankton productivity yet large gaps remain in our understanding of iron's biogeochemical cycle. Here we present the first comprehensive winter dataset for dissolved Fe (dFe) and nitrate (NO3) distributions (0–1000 m depth) between 40S–52S, which transects the Subantarctic zone (SAZ), west of New Zealand. Surface concentrations (<0.2 nmol Fe kg−1) were conspicuously low, i.e., probably biologically limiting even at winter-reserve levels, at frontal zones between 43S (Subtropical Front) and ∼51S (Subantarctic Front). A fivefold range in Fe:NO3 molar ratios was observed along the transect, with Subtropical waters, where blooms occur, having the highest ratios in subsurface waters. The major wintertime supply of dFe in the SAZ is from Ekman advection of waters from the south (but calculated source water dFe is ∼0.2 nmol Fe kg−1), suggesting that mixed-layer dFe concentration is controlled by how long these southern waters remain at the surface (∼3 years).
History
Publication title
Geophysical Research LettersVolume
35Issue
11Article number
L11604Number
L11604Pagination
1-6ISSN
0094-8276Department/School
Institute for Marine and Antarctic StudiesPublisher
Amer Geophysical UnionPlace of publication
2000 Florida Ave Nw, Washington, USA, Dc, 20009Rights statement
Copyright 2008 American Geophysical Union.Repository Status
- Open