Dekun Huang

Temporal variations of atmospheric depositional fluxes of 7Be and 210Pb over 8 years (2006–2013) at Shanghai, China, and synthesis of global fallout data

7Be and 210Pb, two atmospherically delivered radionuclides, have been broadly applied to study the processes including air mass transport, soil erosion, and particle cycling in aqueous systems. These studies require temporal variations of their depositional fluxes. In the present work, monthly atmospheric bulk depositional fluxes of 7Be and 210Pb were measured over 8 years (December 2005 to December 2013) at Shanghai, China. The bulk depositional fluxes of 7Be and 210Pb varied from 17.9 to 421 Bq m−2 month−1 and 6.8 to 82.1 Bq m−2 month−1, respectively. The volume-weighted activities ranged from 0.20 to 8.06 Bq L−1 for 7Be and 0.05 to 3.40 Bq L−1 for 210Pb. There were strong seasonal variations in the depositional fluxes of these nuclides. The seasonal fraction of depositional fluxes was >30% of the total annual depositional fluxes of 210Pb in winter and 7Be in spring. The lowest depositional fluxes were found in summer for both radionuclides, with precipitation-normalized enrichment factor (α) values of 50 km) and increase with the amount of precipitation in onshore region (distance from the coast ≤50 km). We also report that Shanghai, China, has the second highest bulk depositional fluxes of 210Pb in literature.

Intercalibrated radionuclide activities in spiked water samples of the IAEA worldwide open proficiency test

Proficiency testing is one of methods for regularly assessing the accuracy of the analytical data produced by laboratories for particular measurements. In 2008 and 2010, we participated in the IAEA 2008 and 2010 worldwide open proficiency tests on the determination of natural radionuclides in water spiked with 226Ra, 234U and 238U for activity analysis and with 90Sr and 230Th for gross alpha/beta analysis. Feedback statistics from the IAEA final report showed that the radioactivities of all of the samples fell within an acceptable range according to the IAEA. For 226Ra analysis, our result showed that 229Th–225Ra is suitable as a chemical tracer, although there are doubts that different co-precipitation efficient between parent 229Th and its daughter nuclide 225Ra in published literature. The impact factors of the analysis results, such as the lower limit of detection, standard substances, the background and efficiency for daily determination, are discussed in detail.