International Atomic Energy Agency
Department of Nuclear Sciences and Applications
IAEA Environment Laboratories
Vienna International Centre, P.O. Box 100, 1400 Vienna, Austria
REFERENCE SHEET
CERTIFIED REFERENCE MATERIAL
IAEA-446
RADIONUCLIDES IN BALTIC SEA SEAWEED (Fucus vesiculosus)
Certified values for massic activities
(Based on dry mass)
Radionuclide
40
K
137
228
Certified value
-1
[Bq kg ]
660
95% Confidence interval
-1
[Bq kg ]
626 – 671
Cs
18.8
18.2 – 19.2
Ra
15.4
15.0 – 16.7
10.5
10.0 – 11.0
234
U
239+240
Pu
0.024
0.022 – 0.026
Reference date for decay correction: 1 August 2006
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Information values for massic activities
(Based on dry mass)
Radionuclide
Information value
-1
[Bq kg ]
95% Confidence interval
-1
[Bq kg ]
90
Sr
5.1
4.5 – 5.3
99
Tc
14.8
13.8 – 20.2
10.9
10.2 – 12.0
17.0
14.2 – 18.9
15.0
12.6 – 15.5
210
210
Pb( Po)
226
$
Ra
228
Th
230
Th
0.36
0.22 – 0.38
232
Th
0.38
0.30 – 0.46
235
U
0.44
0.27 – 0.52
238
U
9.34
8.98 – 10.96
239
Pu
0.014
0.012 – 0.015
240
0.010
0.009 – 0.014
Pu
$ 210
Pb and 210Po are considered to be in equilibrium
Reference date for decay correction: 1 August 2006
Origin and preparation of the material
A total of 718 kg wet mass of seaweed (bladder wrack, Fucus vesiculosus) was collected from a coastline in the
western part of the Baltic Sea (54°57' N, 11°59' E) between 11 and 27 July 2006 by the Risø National
o
Laboratory, Denmark. The seaweed was first dried in open air and subsequently in heating cabinets at 85 C
leaving a total dry mass of 105 kg. The sample was then ground into powder, sieved through a 250 µm mesh,
homogenized by mixing in a nitrogen atmosphere, bottled in polyethylene sealed bottles (100g units) and
coded as IAEA-446 (for a total of 900 bottles). All bottles were sterilized according to ISO standards at 10 kGy
60
( Co) in an irradiation facility (Isotron, France).
Characterization study
The IAEA-446 candidate reference material was characterized in an interlaboratory comparison (ILC) with
participation of 29 laboratories including the IAEA’s Radiometrics Laboratory, Monaco. This ILC was organized
in 2010 with the aim of giving the participating laboratories the possibility of testing the performance of their
analytical methods on a seaweed sample with elevated radionuclide levels due to the influence of the
historical Chernobyl accident to the Baltic Sea region.
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The laboratories were requested to determine as many radionuclides as possible by gamma-ray spectrometry,
and any possible transuranium radionuclides and other radionuclides requiring radiochemical separation and
alpha or beta counting.
Assignment of values - Certification procedure
The assigned values were established on the basis of results reported by participating laboratories to the
IAEA’s Radiometrics Laboratory in Monaco [1].
The details concerning all reported results as well as the criteria for certification may be found in [1-3]. The
report "Worldwide Laboratory Comparison on the Determination of Radionuclides in IAEA-446 Baltic Sea
Seaweed (Fucus vesiculosus)”, IAEA, 2013 may be downloaded free of charge from:
http://nucleus.iaea.org/rpst/ReferenceProducts/ReferenceMaterials/Radionuclides/index.htm.
All other documents are available upon request.
Evidence on metrological traceability was provided by all laboratories and is summarized in the final report [1].
Based on the evidence on calibrators used, quality control procedures applied by the participating laboratories
and their generally high quality performance in previous IAEA proficiency tests, the Certification Committee
decided to accept these assigned values as certified or information as presented in the Tables above.
Statement on metrological traceability and uncertainty of assigned values
The property values assigned to the IAEA-446 certified reference material are calculated as massic activities of
-1
each radionuclide, expressed in the derived SI unit Bq kg . Measurement uncertainty associated with
individual assigned values is expressed as 95 % confidence interval of the mean of means.
Intended use
This Certified Reference Material is intended to be used for quality assurance/quality control of the analysis of
radionuclides in sediment samples, for the development and validation of analytical procedures and for
training purposes.
Instructions for use
The reference material is supplied in 100 g units. The minimum sample mass laboratories should take when
using the IAEA-446 CRM is 0.3 g for alpha spectrometry, 0.2 g for mass spectrometry, 0.5 g for liquid
scintillation counting and 10 g for gamma spectrometry.
To overcome potential segregation effects due to storage, the material should be re-homogenized before use.
Homogeneity of the material
137
40
90
210
214
226
228
230
232
Sample homogeneity was checked by the determination of Cs, K, Sr, Po, Bi, Ra, Th, Th, Th
239+240
and
Pu activities in 10 bottles randomly chosen. The first homogeneity test between bottles was done for
10 × 3 aliquots chosen at random at different masses of samples (between 10 g and 20 g, between 50 g and
210
60 g for gamma spectrometry, beta counting, and alpha spectrometry, except a small amount of 0.5 g for Po
analysis by alpha spectrometry). The second test within bottles was done for another 10 × 3 aliquots at 5 g to
10 g of sample for gamma emitters and Pu isotopes analysis by alpha spectrometry and 0.2 g of material for U
isotopes determination using ICP-MS, respectively. Homogeneity was tested by using one-way analysis of
variance. The coefficient variation was below 15 % – 20 % for all radionuclides determined, depending on their
activity range. The "between samples" variances showed no significant differences from the "within sample"
variances for the radionuclides tested. Results were identical within statistical uncertainties.
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An additional homogeneity test for major and trace elements (P, S, Cl, K, Ca, Fe, Ni, Cu, Zn, As, Br, Sr, I, Ba and
Pb) for 4 g of the Fucus vesiculosus sample was done by XFR. The coefficient of variation was below 10% for
XRF determined elements.
Dry mass determination
The moisture content of the sample was found to be approximately 5.5%. As the results were reported on a
dry mass basis, the moisture content of the samples should be determined prior to use by drying at 60C in an
oven until a constant mass is obtained and the results corrected accordingly.
Handling and storage
The original unopened bottle should be stored securely at ambient temperature in a dry place. Analysts are
reminded to take appropriate precaution in order to avoid contamination of the material during handling.
Issue and expiry date
The issue date of this reference material is February 2013. The expiry date is February 2023. The IAEA is
monitoring the long term stability of the material and customers will be informed in case of any observed
change.
Legal disclaimer
The IAEA makes no warranties, expressed or implied, with respect to the data contained in this reference
sheet and shall not be liable for any damage that may result from the use of such data.
Compliance with ISO Guide 31:2000
The content of this this IAEA Reference Sheet is in compliance with the ISO Guide 31:2000: Reference
materials – Content of certificates and labels [4].
Citation of this reference sheet
It is suggested to cite this reference sheet according to the following example, as appropriate to the citation
format used: INTERNATIONAL ATOMIC ENERGY AGENCY, Reference Sheet for IAEA-446, Radionuclides in Baltic
Sea seaweed (Fucus vesiculosus). IAEA, Vienna, 5 pp. (The latest version published applies; see “Note” below).
Note
Certified values as stated in this reference sheet may be updated if more information becomes available. Users
of this material should ensure that the reference sheet in their possession is current. The current version may
be found in the IAEA’s Reference Materials online catalogue:
http://nucleus.iaea.org/rpst/ReferenceProducts/ReferenceMaterials
Further information:
For further information regarding this material, please contact:
Radiometrics Laboratory
International Atomic Energy Agency
Environment Laboratories
4, Quai Antoine 1er
MC 98000 MONACO
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Tel.: 377 97 97 72 72
Fax: 377 97 97 72 73
E-mail: [email protected]
REFERENCES
[1]
INTERNATIONAL ATOMIC ENERGY AGENCY, Worldwide Laboratory Comparison on the Determination
of Radionuclides in IAEA-446 Baltic Sea Seaweed (Fucus vesiculosus), IAEA Analytical Quality in
Nuclear Applications No. 25 (IAEA/AQ/25), IAEA, Vienna (2013).
[2]
POVINEC, P.P., PHAM, M.K., IAEA reference materials for quality assurance of marine radioactivity
measurements, J. Radioanal. Nucl. Chem. 248 1 (2001) 211–216.
[3]
SANCHEZ-CABEZA, J.-A., PHAM, M.K, POVINEC, P.P., IAEA programme on the quality of marine
radioactivity data, J. Environ. Rad. 99 (2008) 1680–1686.
[4]
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION, Reference materials
certificates and labels, ISO Guide 31: 2000, ISO, Geneva (2000).
Mr Ales Fajgelj
Chair,
RM Certification Committee
RS_IAEA-446/2013-02-19
– Content of
Ms Mai Khanh Pham
Project Officer,
Radiometrics Laboratory
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