IAEA-385 , Irish Sea Sediment

Inorganic , Sediments

A sample of about 250 kg of sediment was collected from the Irish Sea (54.3°N, 3.7°W) by the Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Lowestoft, U.K., in 1995. The sediment, which was sent to IAEA-MEL for processing, was frozen for 2 hours at -40°C, and then freeze-dried with a +5°C/h temperature increase rate. Secondary drying was performed over 24 hours under 0.02 mbar pressure at a constant temperature of +40°C. The sediment was then ground into powder, sieved through a 250 µm mesh and homogenized by mixing in a nitrogen atmosphere. The samples were bottled in polyethylene flasks under nitrogen gas, sealed with polyethylene caps and labeled with the code IAEA-385. The bottles containing 100 g of sediment powder each were sterilized according to ISO standards at 25 kGy in an irradiation facility.

Reference date for decay correction: 1996-01-01

Certified values for massic activities (based on dry mass)
Radionuclide Certified value [Bq kg-1] 95% Confidence interval [Bq kg-1]
40K 607 604-612
137Cs 33.0 32.7-33.6
226Ra 21.9 21.6-22.4
228Ra 32.0 31.3-32.5
230Th 30.6 30.0-33.6
232Th 33.7 32.8-33.9
234U 27 26-28
238U 29 28-30
238Pu 0.44 0.42-0.48
239+240Pu 2.96 2.89-3.00
241Am# 3.84 3.78-4.01

# The values should be corrected for in-growth from 241Pu.

Information values for massic activities (based on dry mass)
Radionuclide Information value [Bq kg-1] 95% Confidence interval [Bq kg-1]
90Sr 0.58 0.42-0.68
210Pb(210Po)$ 32.9 31.2-35.3
235U 1.34 1.25-1.44
239Pu 1.92 1.30-2.07
240Pu 1.18 0.97-1.32
241Pu 30 26-32

$ 210Pb and 210Po are considered to be in equilibrium.

The values listed above were established on the basis of statistically valid results submitted by laboratories which had participated in an international interlaboratory comparison organized by the IAEA Marine Environment Laboratories, Monaco. The details concerning the criteria for qualification as a certified or information value may be found in the report IAEA/AL/151 (attached). 

Help and Service
Copyright © 2009 International Atomic Energy Agency, P.O. Box 100, Wagramer Strasse 5, A-1400 Vienna, Austria