Global Biogeochemical Cycles
We report iron measurements for water column and aerosol samples collected in the Sargasso Sea during July-August 2003 (summer 2003) and April-May 2004 (spring 2004). Our data reveal a large seasonal change in the dissolved iron (dFe) concentration of surface waters in the Bermuda Atlantic Time-series Study region, from ∼1-2nM in summer 2003, when aerosol iron concentrations were high (mean 10 nmol/m-3), to ∼0.1-0.2nM in spring 2004, when aerosol iron concentrations were low (mean 0.64 nmol/m-3). During summer 2003, we observed an increase of ∼0.6nM in surface water dFe concentrations over 13 days, presumably due to eolian Fe input; an estimate of total Fe deposition over this same period suggests an effective solubility of 3-30% for aerosol iron. Our summer 2003 water column profiles show potentially growth-limiting dFe concentrations (0.02-0.19nM) coinciding with a deep chlorophyll max. at 100-150 m depth, where phytoplankton biomass is typically dominated by Prochlorococcus during late summer.
Original Publication Citation
Sedwick, P.N., Church, T.M., Bowie, A.R., Marsay, C.M., Ussher, S.J., Achilles, K.M., . . . McGillicuddy, D.J. (2005). Iron in the Sargasso Sea (Bermuda Atlantic time-series study region) during summer: Eolian imprint, spatiotemporal variability, and ecological implications. Global Biogeochemical Cycles, 19(GB4006), 1-11. doi: 10.1029/2004GB002445
Sedwick, Peter N.; Church, T. M.; Bowie, A. R.; Marsay, C. M.; Ussher, S. J.; Achilles, K. M.; Lethaby, P. J.; Johnson, R. J.; Sarin, M. M.; and McGillicuddy, D. J., "Iron in the Sargasso Sea (Bermuda Atlantic Time-Series Study Region) During Summer: Eolian Imprint, Spatiotemporal Variability, and Ecological Implications" (2005). OEAS Faculty Publications. 89.