An International Marine-Atmospheric222Rn Measurement Intercomparison in Bermuda Part II: Results for the Participating Laboratories.
As part of an international measurement intercomparison of instruments used to measure atmospheric222Rn, four participating laboratories made nearly simultaneous measurements of222Rn activity concentration in commonly sampled, ambient air over approximately a 2 week period, and three of these four laboratories participated in the measurement comparison of 14 introduced samples with known, but undisclosed ("blind")222Rn activity concentration. The exercise was conducted in Bermuda in October 1991. The222Rn activity concentrations in ambient Bermudian air over the course of the intercomparison ranged from a few hundredths of a Bq · m-3to about 2 Bq · m-3, while the standardized sample additions covered a range from approximately 2.5 Bq · m-3to 35 Bq · m-3. The overall uncertainty in the latter concentrations was in the general range of 10 %, approximating a 3 standard deviation uncertainty interval. The results of the intercomparison indicated that two of the laboratories were within very good agreement with the standard additions, and almost within expected statistical variations. These same two laboratories, however, at lower ambient concentrations, exhibited a systematic difference with an averaged offset of roughly 0.3 Bq · m-3. The third laboratory participating in the measurement of standardized sample additions was systematically low by about 65 % to 70 %, with respect to the standard addition which was also confirmed in their ambient air concentration measurements. The fourth laboratory, participating in only the ambient measurement part of the intercomparison, was also systematically low by at least 40 % with respect to the first two laboratories.
National Institute of Standards and Technology, Gaithersburg, MD 20899-0001, USA.
R
R
Collé
National Institute of Standards and Technology, Gaithersburg, MD 20899-0001, USA.
M P
MP
Unterweger
National Institute of Standards and Technology, Gaithersburg, MD 20899-0001, USA.
J M R
JM
Hutchinson
Australian Nuclear Science and Technology Organization, PB1, Menai, NSW 2234 Australia.
S
S
Whittlestone
Centre des Faibles Radioactivités, Laboratoire Mixte, C.N.R.S-C.E.A., 91198 Gif-sur-Yvette, France.
Georges
G
Polian
Centre des Faibles Radioactivités, Laboratoire Mixte, C.N.R.S-C.E.A., 91198 Gif-sur-Yvette, France.
Bénédicte
B
Ardouin
Atmospheric Chemistry Laboratories, Department of Chemistry, Drexel University, 32nd & Chestnut Streets, Philadelphia, PA 19104, USA.
Jack G
JG
Kay
Atmospheric Chemistry Laboratories, Department of Chemistry, Drexel University, 32nd & Chestnut Streets, Philadelphia, PA 19104, USA.
James P
JP
Friend
Atmospheric Chemistry Laboratories, Department of Chemistry, Drexel University, 32nd & Chestnut Streets, Philadelphia, PA 19104, USA.
Byron W
BW
Blomquist
Atmospheric Chemistry Laboratories, Department of Chemistry, Drexel University, 32nd & Chestnut Streets, Philadelphia, PA 19104, USA.
Wolfgang
W
Nadler
Atmospheric Chemistry Laboratories, Department of Chemistry, Drexel University, 32nd & Chestnut Streets, Philadelphia, PA 19104, USA.
Thomas T
TT
Dang
Environmental Measurements Laboratory, U.S. Department of Energy, New York, NY 10014, USA.
R J
RJ
Larsen
Environmental Measurements Laboratory, U.S. Department of Energy, New York, NY 10014, USA.
A R
AR
Hutter
air; environment; intercomparison; marine atmosphere; measurement; radon-222