Inter-laboratory comparison for sea water CO2 measurements planned for 2012

A message from Clara Hoppe, Dieter Wolf-Gladrow, Andrew Dickson

The goal of this inter-laboratory comparison is to assess the present quality of sea water CO2 measurements for total alkalinity, total dissolved inorganic carbon, and pH. It is thus relevant to the marine science community as well as to laboratories involved in ocean acidification activities.

The test samples will be prepared in Andrew Dickson’s laboratory at the Scripps Institution of Oceanography, and will comprise four 500 mL bottles of different sea waters (two samples, each in duplicate), with one sample having a low p(CO2) at 20 °C (ca. 400 µatm) and the other a high p(CO2) (ca. 1200 µatm). The samples will also be analyzed at Scripps to provide reference values for the comparison.

Test samples will be available either from the Dickson laboratory in San Diego (California, USA) or from the Alfred Wegener Institute (AWI, Bremerhaven, Germany). It is expected that the samples will be available for distribution by May 1, 2012; and we plan that the results should be submitted to the organizers by September 1, 2012. The costs for participation are expected to be about US $150 (+ the costs of shipping).

At this time, we should like to assess the degree of interest in the community for such an inter-laboratory comparison. If you would be interested in participating, please contact Clara Hoppe ( or Andrew Dickson ( indicating your interest. Please also indicate what kinds of samples (open ocean, coastal, estuarine, from ocean acidification experiments, etc.) you normally analyze, as well as which measurements of the CO2 system you would plan to make on the test samples.

Clara Hoppe, Dieter Wolf-Gladrow, Andrew Dickson