photo of SAfe Scientific Party, 2004
SAFe Scientific Party, 2004

Sampling and Analysis of Iron (SAFe)

An international collaboration
Principal Investigator - Ken Johnson, Monterey Bay Aquarium Research Institute
Co-PI - Ken Bruland, UC Santa Cruz
Co-PI - Kenneth Coale, Moss Landing Marine Labs
Funded by the National Science Foundation
photo of Geo and Mike hanging a 30-L GO-flo bottle
Geo and Mike hanging a 30-L GO-flo bottle

The goal of this project was to conduct a collaborative exercise among a large group of experienced analysts to determine dissolved iron concentrations at sea and in the laboratory. This exercise focused on the entire spectrum of activities involved in making iron measurements, ranging from sampling, filtration, storage and analysis. A series of samples were archived for analysis in shore based laboratories to ensure that all types of analytical methods for iron were considered and distributed as an iron in sea water referencde material.

photo of Landing/Measures CLIVAR rosette
Landing/Measures CLIVAR rosette

Where differences were apparent, the work established the basis needed to assess the mechanisms that accounted for the difference. Ultimately, the goal is to enable the ocean science community to compare measurements of dissolved iron (and other trace metals) made at different places and times in the ocean with a high degree of confidence in the differences or similarities that are detected.

photo of Geo, Tina and Mike (in reflection) bottling SAFe samples.
Geo, Tina and Mike (in reflection) bottling SAFe samples

This project was an international multi-institutional collaboration designed to resolve differences that remain in measurements of iron in seawater. It was led by a Steering Committee of experienced iron analysts (Boyle, Bruland, Coale, Johnson, Measures and Moffett). In addition, a broad spectrum of research groups with extensive experience in measuring iron participated in the collaboration by making measurements at sea (in the US: Landing, Sedwick, Wu; in Europe: Blain, Croot, de Baar, van den Berg, Worsfold; in Japan: Obata, Takahashi).

photo of Ed Boyle and Ron Comer rigging the MITESS
Ed Boyle and Ron Comer rigging the MITESS

The broader impacts of this project extend to a variety of areas. The results will greatly enhance the infrastructure for ocean observations across space and time by allowing trace metals measurements to be broadly intercompared with the confidence that measurements are compatible. Without such assurance, global surveys and time series observations are nearly impossible.

Although education is not a direct component of this work, the results will enable consistent measurements of iron and trace metals concentrations at the graduate student level - a task that was often prohibitive due to the high level of training that was required.


Johnson, K., E. Boyle, K. Bruland, K. Coale, C. Measures, J. Moffett, A. Aguilar-Islas, K. Barbeau, B. Bergquist, A. Bowie, K. Buck, Y. Cai, Z. Chase, J. Cullen, T. Doi, V. Elrod, S. Fitzwater, M. Gordon, A. King, P. Laan, L. Baquer, W. Landing, M. Lohan, J. Mendez, A. Milne, H. Obata, L. Ossiander, J. Plant, G. Sarthou, P. Sedwick, G. Smith, B. Sohst, S. Tanner, S. Van den Berg, J. Wu. Developing standards for dissolved iron in seawater. EOS, 88: 131-132 (2007).

Lohan, M.C., A.M. Aguilar-Islas and K.W. Bruland. Direct determination of iron in acidified (pH 1.7) seawater samples by flow injection analysis with catalytic spectrophotometric detection: Application and intercomparison. Limnology & Oceanography: Methods, 4: 164-171 (2006).

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The development of this website and most of the research described here was supported by grants from the National Science Foundation.
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