Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1738786 | Journal of Environmental Radioactivity | 2010 | 9 Pages |
Abstract
In order to investigate the applicability of 212Pb as a tracer for atmospheric transport in the sub-regional scale (few hundred kilometers in horizontal direction and up to â¼1Â km by height), we measured the air concentrations of the short-lived radionuclide 212Pb along with the long-lived 7Be and 210Pb near the ground surface. For this purpose, simultaneous observations were continued for several days at three locations: a reference point representative for standard land surface atmosphere conditions, a second location at an altitude 650Â m near the reference point, and on a solitary island â¼180Â km from the reference point. Measurements of radioactivity in aerosol particle samples collected at intervals of 2-3Â h with a high-volume air sampler were performed by extremely low background gamma-ray spectrometry with the use of Ge detectors located at the Ogoya Underground Laboratory. Concentration of 7Be or 210Pb and their variation patterns was found to be similar among the three points during the whole observation period except for moment of the passage of a cold front. The results indicate that distributions of concentrations of the long-lived nuclides were uniform in this range. On the other hand, concentration levels and the variation patterns of the short-lived 212Pb differed greatly from one location to another, reflecting differences in geographical location and altitude of the observation points. Additionally, there were certain indications that observed concentration of 212Pb contained two components: an autogenous component from sources nearby and a heterogenous one from faraway sources carried by atmospheric horizontal transport. Results of this study provide experimental proof that 212Pb can be used as a tracer of sub-regional atmospheric transport.
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Authors
Takuya Abe, Toshiso Kosako, Kazuhisa Komura,