June 2017:

The Town Hall meeting at the 2016 Ocean Sciences Meeting (see the news item for February 2016) was followed up with two web-based surveys of user needs that attracted a total of 166 responses. The results are now being prepared for publication and dissemination, and will guide the development of user-friendly software for chemical speciation modelling.

April to June 2017:

Simon Clegg worked at the University of Gothenburg with WG 145 Chair David Turner to plan the experiments to be carried out at Scripps, LNE, PTB, NMIJ and GEOMAR starting later this year (see the news item below). David has been documenting the current "state-of-the-science" Pitzer model of Tris buffer in seawater at 25°C. This will be the basis of our work on the statistics and uncertainty analysis needed to develop the traceability element of the speciation model.

Collaboration is also developing with Pavel Tischenko of the Pacific Oceanological Institute in Vladivostok (Associate Member of WG 145). Pavel has expertise in Pitzer-based speciation modelling, and experiments using Harned Cells. He has measured the properties of solutions containing major components of the Tris buffers that we are currently working on.

March 2017:

We have begun a collaboration with Daniela Stoica of LNE (Laboratoire national de métrologie et d'essais, in Paris), Frank Bastkowski of PTB (Physikalisch-Technische Bundesanstalt, in Braunschweig), and Igor Maksimov (National Metrology Institute of Japan, NMIJ) to develop a speciation model of the Tris (2-amino-2-hydroxymethyl-propane-1,3-diol) buffers in artificial seawater that are used to calibrate pH instrumentation. This is now an intermediate goal of WG 145, and an important step towards the complete model of seawater. The work will complement the NERC/NSF research project described in the news item below. The three institutes will carry out Harned Cell measurements, which will complement those from Andrew Dickson's group, and enable us to produce a temperature and composition dependent model of the buffer solutions. Additional experiments will be carried out by Pablo Lodeiro at GEOMAR in Kiel. Pablo is part of the group of WG 145 member Eric Achterberg.

January 2017:

Working group members Simon Clegg, Andrew Dickson, and Heather Benway have been awarded funding for a 3 year project "A Thermodynamic Chemical Speciation Model for the Oceans, Seas, and Estuaries". This 3 year project, supported by Natural Environment Research Council of the UK and the National Science Foundation (USA), will help achieve several of the goals of the Working Group. The initial focus of the project will be measurements and modelling the properties of the buffers that are used to calibrate measurements of the pH of seawater.

The project is expected to start in November this year. Experiments will be carried out at Scripps Institution of Oceanography (by Andrew Dickson) and model development at the University of East Anglia (by Simon Clegg). We are very grateful for the involvement of scientists at the national metrological institutes of Germany (Physikalisch-Technische Bundesanstalt, at Braunschweig), France (Laboratoire national de metrologie et d'essais, Paris), Japan (National Metrological Institute of Japan), and the Helmholtz Institute of Ocean Research Kiel. (Eric Achterberg at Kiel is a Working Group member.) Scientists at these institutions will be making substantial contributions to the project by measuring the properties of aqueous solutions of the components of the pH buffer and of seawater, which are important for the development of the speciation model. Their interest is in the "traceability" of pH measurements, and the development of reference standards. The relationship of such studies to model development is discussed in a recent paper co-authored by Andrew Dickson (Metrologia 53, R26-R39, 2016; doi:10.1088/0026-1394/53/1/R26).

September 2016:

Our article 'Towards a quality-controlled and accessible Pitzer model for seawater and related systems' (Frontiers in Marine Science 3, art. 139, 2016; https://doi.org/10.3389/fmars.2016.00139) has been published. The authors are Working Group members David Turner, Eric P. Achterberg, Chen-Tung A. Chen, Simon L. Clegg, Vanessa Hatje, Maria Maldonado, Sylvia G. Sander, Constant M. van den Berg, and Mona Wells.

July 2016:

Working group members Simon Clegg, Andrew Dickson, and Heather Benway have submitted a proposal to NERC in the UK, entitled "A Thermodynamic Chemical Speciation Model for the Oceans, Seas, and Estuaries". The 3 year project, if it receives funding, will involve both experiments and modelling and will help us achieve the goals of the Working Group.

June 2016:

The thermodynamic data upon which Pitzer chemical speciation models are based remain incomplete for some major and minor components of seawater, especially at temperatures other than 25 oC. Here we make recommendations for new measurements of thermodynamic properties, in order of their importance for the calculation of pH and calcite or aragonite saturation.

May 2016:

Working group member Simon Clegg submitted a proposal "Traceable oceanic carbon cycle measurements TOCCMe" to the EU EMPIR research programme. The lead principal investigator was Daniela Stoica of Laboratoire de Métrologie et d’Essais (LNE) in Paris. (Note: although this proposal was not successful it led to the collaboration with three metrology institutes described in the entry for March 2017.

February 2016:

Working group members Sylvia Sander, David Turner, and Simon Clegg led a "Town Hall" at the AGU/ASLO 2016 Ocean Sciences meeting, entitled "Toward a Standard, User-Friendly Chemical Speciation Model for Seawater and Estuarine Waters". At this event we engaged with the chemical oceanography community to understand their interests and needs.

Summary of Working Group Projects:

New measurements and model development (see Figure 1 of our publication in Frontiers in Marine Science)

Component(s) and Systems Applications Working Group Projects
pH buffers in artificial seawater pH measurement, acidification NERC/NSF 3 year funded project. Contacts: Simon Clegg, Andrew Dickson, and Heather Benway
CO2 system modelling Acidification, calcite and aragonite saturation
Trace metals – complexation by natural organic matter Trace metals as micronutrients and geochemical tracers Application of NICA-Donnan modelling to marine natural organic matter. Contacts: David Turner, Martha Gledhill
Trace metals – CLE-CSV ligands Ensuring the quality of measurements of trace metal complexation by natural organic matter
Trace metals – model ligands for laboratory experiments Understanding trace metal bioavailability
Natural organic matter Contribution to alkalinity in estuarine and brackish waters
Sulphidic pore waters and deep waters Diagenesis; release of elements and compounds to the overlying water
Hydrothermal systems (high pressure and temperature Significance as sources and sinks of chemical elements
Polar brines Understanding the CO2 system at the ice-water interface
Salt lakes Evaporite formation