Title: Isotopic compositions of
K. Böhlke, T.B.
Coplen, T.P. Ding,
R.D. Loss, Kevin
J.R. Rosman, P.D.P.
Taylor, T. Walczyk,
and M. Wieser
To design, compile and produce a new Report on the Isotopic Compositions
of selected Elements, containing updated data with uncertainties
that conform to ISO 9001 requirements.
The Commission on Isotopic Abundances and Atomic Weights
(CIAAW) has produced in the past (last one in 2001) several tables
emphasizing the isotopic abundances of the elements. The evaluated
data provided on these tables has usually been selected to represent
a) the best available measurements and b) that present in representative
materials which do not always correspond to the Commission's recommended
standard atomic weights for each element. The inconsistencies between
some of the recommended isotopic abundances and atomic weights has
been requiring our attention for some time which this proposal aims
link to Commission
The second major aim of this project is to address the increasing
importance of isotope ratio measurements in chemistry, geological,
environmental sciences, product authentication, forensic and life
sciences. This project recognizes the primary source of isotopic
data reported in the literature is as ratios and the urgent need
for an expanded and revised database listing isotopic ratios and
isotopic abundances in normal terrestrial materials and associated
reference materials to suit the majority of user communities.
For this reason CIAAW proposes to issue a new authoritative document
to update and disseminate this information. This is a major modification
and expansion of the present compilations and will include a simple
spreadsheet type data base from which a variety of reports can be
extracted and to facilitate future updates.
A major requirement of this project is to re-evaluate the uncertainties
associated with the original data, which necessitates revisiting
all of the original literature, and the development of new data
evaluation guidelines. Because of the time required to re-evaluate
all elements only a set of elements of immediate interest to the
isotope user community will be published in the first instance.
In the first set of elements, iron, tin, europium, dysprosium, and
erbium will be evaluated.
The task group will
- develop and implement new guidelines for data evaluation and presentation
- review and evaluate the isotope ratio data publications for ~10
- prepare a new layout of the spread sheet style data base and sample
- issue the new tables and widely distribute it using suitable channels
August 2007 - The project is a follow on from a previous
project. Various members of the task group have attended a series
of workshops in IRMM Belgium and the Chinese Academy of Geological
Science in Peking to develop a complete and transparent ISO9001
based working protocol for the evaluation of published isotopic
compositions of the element according to ISO 9001 requirements.
The elements evaluated were Pt, Ta, La, Nd, Zn and Cr.
The protocols and evaluations were recommended to the next Commission
on Isotopic Abundances and Atomic weights for approval at the Commission
at the PISA 2007 meeting. During this meeting the Commission approved
these protocols be trialed for the next (2007-2009) published isotopic
composition evaluation period.
A full report describing the details of proposed CIAAW guidelines
for determining best measurements of isotopic compositions and representative
isotopic compositions, and for calculating atomic weights and full
uncertainties is available. The report also illustrates the templates
and forms to be used in future evaluations. A spreadsheet/data base
system has also been developed to simplify the evaluation process
and clearly show calculation paths. The report has been prepared
by Michael Berglund, JK Böhlke, and Bob Loss.
Last update: 20 August 2007