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Macronutrient and trace-metal geochemistry of an in situ iron-induced Southern Ocean bloom
journal contribution
posted on 2023-05-16, 14:03 authored by Frew, R, Andrew BowieAndrew Bowie, Croot, P, Pickmere, SWe have investigated the effect of iron supply and increased phytoplankton growth on the cycling of the macronutrients phosphate, nitrate and silicic acid as well as the micronutrients copper (Cu), nickel (Ni), zinc (Zn) and cadmium (Cd). Nutrient levels were measured in situ in an iron-induced phytoplankton bloom at 61°S 140°E in the Southern Ocean Iron Release experiment (SOIREE). Nutrient ratios upon arrival at the study site indicate that much of the seasonal phytoplankton productivity was by iron-limited diatoms growing at low mean light levels. The addition of iron (Fe) induced a bloom that led to a draw-down in the macronutrients in ratios consistent with the growth of diatoms under iron-replete conditions. None of the bioutilised trace metals Cu, Ni, Zn or Cd showed any indication of co-limitation, with Fe, of phytoplankton growth. Zn concentrations did not decrease by algal uptake as expected. Cd was partitioned to the particulate phase indicating consumption by the algae. Cd was preferentially utilised with respect to P with a αCd/P = 5.8. Interpretation of the Cd/Ca data from the sedimentary record using this higher induced αCd/P value would imply even higher Southern Ocean surface water P during the last glacial maximum. © 2001 Elsevier Science Ltd.
History
Publication title
Deep-Sea Research II-Topical Studies in OceanograghyVolume
48Issue
11-12Pagination
2467-2481ISSN
0967-0645Department/School
Institute for Marine and Antarctic StudiesPublisher
Pergamon-Elsevier Science LtdPlace of publication
OxfordRepository Status
- Restricted