An example of a fruitful international intercomparison

The reliability of the GEOTRACES data products including the eGEOTRACES Electronic Atlas is strongly related to the quality of the data acquired by the different laboratories contributing to this international effort. A key aspect for assessing this quality relies on the good intercomparison of the trace metal data. Iron (Fe) concentrations and moreover Fe isotopes count among the most delicate parameters to be measured in seawater.

Conway (Switzerland), John (USA) and Lacan (France) (2016, see reference below) present the first comparison of dissolved Fe stable isotope ratio profiles in the oceans, analyzed at different depths at 3 different GEOTRACES crossover stations in the Atlantic Ocean (Bermuda Atlantic Time Series Station, off Cape Verde and in the Cape Basin, south Atlantic).

Having assessed the strong agreement between data and profiles measured by 5 different laboratories at Bermuda Atlantic Time Series (BATS), the authors discuss the temporal variability observed at the three locations, taking advantage of reoccupation of the stations by multiple cruises on a 1-3 year timescale. The authors find that the deep ocean at these locations is largely invariant for Fe isotopes on these timescales, but that there is variability in surface waters and near low-oxygen margins.

16 Conway l
Comparison of δ56Fe (relative to IRRM-014) and Fe data from Bermuda Atlantic Time Series (BATS) in the subtropical North West Atlantic (31.75°N 64.17°W) from the U.S. GEOTRACES IC1 (June 2008) and GA03 cruises (USGT11, Nov. 2011). Data are reproduced from Boyle et al. (2012); Conway and John (2014a); Conway et al. (2013a; 2013b); John and Adkins (2012). Please click here to view the figure larger.


Conway, T. M., John, S. G., & Lacan, F. (2016). Intercomparison of dissolved iron isotope profiles from reoccupation of three GEOTRACES stations in the Atlantic Ocean. Marine Chemistry. doi:10.1016/j.marchem.2016.04.007

> Figure references:

Boyle et al., 2012: E.A. Boyle, S.G. John, W. Abouchami, J.F. Adkins, Y. Echegoyen-Sanz, M.J. Ellwood, A.R. Flegal, K. Fornace, C. Gallon, S. Galer, M. Gault-Ringold, F. Lacan, A. Radic, M. Rehkämper, O. Rouxel, Y. Sohrin, C. Stirling, C. Thompson, D. Vance, Z. Xue, Y. Yhao. GEOTRACES IC1 (BATS) contamination-prone trace element isotopes Cd, Fe, Pb, Zn, Cu, and Mo intercalibration. Limnol. Oceanogr. Methods, 10 (2012), pp. 653–665. doi: 10.4319/lom.2012.10.653

Conway and John, 2014a: T.M. Conway, S.G. John. Quantification of dissolved iron sources to the North Atlantic Ocean Nature, 511 (2014), pp. 212–215. doi:  10.1038/nature13482

Conway et al., 2013a:  T.M. Conway, A.D. Rosenberg, J.F. Adkins, S.G. John. A new method for precise determination of iron, zinc and cadmium stable isotope ratios in seawater by double-spike mass spectrometry Anal. Chim. Acta, 793 (2013), pp. 44–52. doi: 10.1016/j.aca.2013.07.025

Conway et al., 2013b: T.M. Conway, A.D. Rosenberg, J.F. Adkins, S.G. John. Corrigendum to “A new method for precise determination of iron, zinc and cadmium stable isotope ratios in seawater by double-spike mass spectrometry.” Anal. Chim. Acta, 801 (97) (2013). doi: 10.1016/j.aca.2013.09.010

John and Adkins, 2012: S.G. John, J.F. Adkins. The vertical distribution of iron stable isotopes in the North Atlantic near Bermuda Glob. Biogeochem. Cycles, 26 (2) (2012) doi: 10.1029/2011GB004043



Isotopes Atlantic Ocean Iron Global scale Pacific Ocean Neodymium Neodymium isotopes Particles Multiple TEIs Southern Ocean Zinc Thorium Land-ocean inputs Hydrothermal Arctic Ocean Analysis Modelling Circulation Cadmium Land-ocean input Thorium isotopes Data compilation Indian Ocean Cycles Mercury Radium Speciation Barium Silicon Aerosol input Iron isotopes Copper Manganese Hypoxia Radium isotopes Phosphate Cobalt Rare Earth Element Lead Lead isotopes Aluminium Protocol Mediterranean Sea Aerosols Boundary Exchange Protactinium Thorium-Protactinium Paleoceanography Environmental change Organic matter Nepheloids Aerosol Cadmium isotopes Zinc isotopes International Polar Year Uranium Microbial Rare Earth Elements Benthic Limitation Phytoplankton Oxygen Silicon isotopes Chromium Chronium isotopes BioGEOSCAPES Particulate Organic Carbon Export fluxes Residence times Methylmercury Surface waters Helium Paleocirculation Proxy Nickel Remineralization Nitrogen Sediments Climate change Lanthanum Yttrium Scandium Intercalibration Lithogenic Macronutriments Micronutriments Hafnium Hafnium isotopes Ice Sea ice Helium isotopes Particle fluxes Barium isotopes Biological pump Iodine Uranium isotopes Artificial Intelligence Cadmium sulfide Antarctic geology Beryllium Mammals Phosporus Time Series Productivity Red Sea Distribution coefficient Mesoscale transport Fertilisation Processes Estuaries Mesopelagic Anoxia Black Sea ICPMS Ecosystem CO2 degassing Transmissiometer Eddy Kinetic Energy Fate Scavenging Fractionation Distribution Iron sulfide Precipitation Shelf Inputs River Pitzer equations Gadolinium Intercomparison Coastal area Gallium Submarine Ground Water Discharge Cooper isotopes Total Hg Fertilization Experiments Behavior Budget Atmospheric Dynamic SAFE samples Boundary Scavenging Procedure Osmium Arsenic Aerosols input Nitrate Nutrients Deep water Copper isotopes Dissolved concentations

 Data Product (IDP2017)


 Data Assembly Centre (GDAC)


Subscribe Mailing list

Contact us

To get a username and password, please contact the GEOTRACES IPO.

This site uses cookies to offer you a better browsing experience. Find out more on how we use cookies and how you can change your settings.