This is a summary of news about our current activities.

Experiments

Pablo at GEOMAR has just completed the first of a series of measurements of the solubility of Tris in aqueous NaCl solutions at different temperatures. The data, together with the results of Harned Cell experiments to be carried by other WG 145 members, will be used to quantify the effects of Na+ and Cl- ions on Tris activity coefficients and to determine the values of interaction parameters in the Pitzer speciation model we are developing.

At Scripps Institution of Oceanography Andrew Dickson will very shortly have a new technician “in post”, who will be carrying out many of the Harned Cell experiments that we have planned for our project. One of his first tasks, after training, will be to take part in an inter-laboratory comparison of Harned cell measurements of emfs of a small number of standard solutions. Andrew Dickson’s laboratory will produce one set of these standard solutions, batches of which will be distributed to all laboratories. In addition, each laboratory will prepare samples of the same solutions, and measure both sets. The following laboratories are taking part: Scripps Institution of oceanography, NIST (Gaithersburg, USA), PTB (Braunschweig, Germany), LNE (Paris, France), NMIJ (Japan).

We are currently discussing our project with Jelena Miladinovic and her colleagues at the Faculty of Technology and Metallurgy, University of Belgrade. They are one of relatively few groups who carry out isopiestic experiments (very accurate measurements of water activity), which would be a valuable complement to Harned Cell data (which yield HCl activity products). We hope that Jelena and her group will be able to join our collaboration and, later this year, measure water activities of some of the key mixtures of Tris and seawater salts.

Other

David, Heather, Simon, and other members of WG 145 are preparing a manuscript describing the results of our online survey of chemical oceanographers regarding their usage/needs for chemical speciation models, and the reviews of current models carried out by WG 145 members early in the life of this Working Group. The manuscript will also contain our detailed proposals for the speciation modelling tools that will be produced by WG 145 (chemical species includes, inputs and outputs, links with “core” chemical oceanography models such as CO2SYS, etc.). It is expected that our survey results will be placed on this website, both in order to be referenced by the manuscript and for general comment.

Meetings

At the beginning of September 2018, in Prague, there is an ICPWS conference (17th International Conference on the Properties of Water and Steam). Andrew Dickson will be participating in the session and workshop “Marine chemistry and seawater pH”. It is likely that Simon Clegg will attend too, in order to talk about our project. We hope other members of the collaboration will also be able to come to the meeting. The detailed programme of the conference isn’t available yet, but the website is http://www.icpws2018.com/.