Following the success of WG 145 members Simon Clegg, Heather Benway, and Andrew Dickson in obtaining 3 year grants from NERC (in the UK) and NSF in the USA, we are very pleased to announce major additions to our collaboration:

• Frank Bastkowski and Steffen Seitz, of Physikalisch-Technische Bundesanstalt (PTB), Braunschweig.
• Igor Maksimov and Toshiaki Asakai, of the National Metrology Institute of Japan.
• Daniela Stoica, of the Laboratoire national de métrologie et d’essai, Paris.
• Pablo Lodeiro and Eric Achterberg, of GEOMAR (the Helmholtz Institute of Ocean Research, Kiel).

The first three groups will all be making Harned Cell measurements of HCl activities in solutions containing Tris/TrisH+ buffer, and the components of seawater (beginning with NaCl).

Pablo and Eric will be measuring salt solubilities in aqueous mixtures, to obtain values of the activities of the salts at saturation. They may also be carrying out potentiometric titrations.

The purpose of both types of experiments is to obtain the activities of dissolved species in the solutions, and so determine the parameters of the Pitzer the chemical speciation model we are developing. These parameters, whose values are functions of temperature and pressure, express the strength of interactions between pairs of cations and anions, and then triplets of ions (two ions of one sign, and one ion of opposite sign). They can only be determined by fitting to measurements.