Intercalibration of radionuclides for IDP2017

Subject: Intercalibration of radionuclides for IDP2017

Dear Colleagues,

Please read this letter if you are involved in the analysis of radionuclides in seawater as part of GEOTRACES. I am sending this letter as a new member of the GEOTRACES standards and intercalibration (S&I) committee. As a committee, we are trying to ensure that data going into the official GEOTRACES products meet certain quality criteria, and my main responsibility will be to oversee the radionuclide data.

The next GEOTRACES intermediate data product (IDP2017) is already in preparation, and you should have received a letter detailing submission deadlines and general instructions. The actual intercalibration procedure is supposed to be done by the submitting researchers. As a committee, we will then look at the information submitted with the data, and decide whether your intercalibration is compliant with GEOTRACES standards, and consequently approved for IDP2017.

However, the situation is sometimes a bit complicated for radionuclides. Some require excessive volumes, others have very short half-lives, and again others can only be measured in a very limited number of labs- resulting in difficulties when you are trying to comply with intercalibration requirements, like crossover stations, CRMs, or replicates. You know these issues.

We have learned a lot from the intercalibration exercises already, and from the previous round of validations for the last IDP. Many potential issues have already been identified and solved, but there are still a number of questions in the community regarding what to observe when submitting radionuclide data to the S&I committee. In addition, new isotope systems and methods are constantly being added to the portfolio.

In order to clarify what can and will be expected in IDP2017 for individual radionuclide systems, I have therefore decided to create a document that will help us to identify the relevant issues, and come up with general criteria, but also with specific requirements for each isotope system. As you will be aware, there is a significant number of radionuclides in the ocean, and many ways of analyzing them.

I am now circulating a draft of this document, seeking your input and opinion, especially on the isotopes that I am less familiar with. This document has already been circulated amongst the lead authors of the existing intercalibration exercises, and now you are invited to comment on it. You can point out issues (or even isotopes) that you think have been overlooked, or just make general comments on the intercalibration procedures.

I’d like to state very clearly that this is not (yet) an official GEOTRACES document. At this stage, it is just an invitation to contribute to the competent validation of your data for the next IDP. In any case, I feel that it should help to make the intercalibration procedure more transparent for everyone.

Please forward this email to colleagues who you think might be interested; it should be circulated as widely as possible.

I’m looking forward to hearing from you via email: . I am away from my office until 2nd November, but I will respond after I have returned (it may still take a while, depending on the response to this enquiry).

Kind Regards,


Dr Walter Geibert

Alfred Wegener Institute
Helmholtz Centre for Polar and Marine Research
Am Handelshafen 12, 27570 Bremerhaven, Germany
phone: 0049 471 4831 2418