Study of the naturally occurring radionuclide Beryllium-7 (Be-7) in Hong Kong

Beryllium-7 (Be-7) is one of the naturally occurring radionuclides being monitored under the Global Atmosphere Watch Programme of the World Meteorological Organization. Be-7 mainly originates from cosmic rays. It can be used as a tracer to facilitate understanding of the atmospheric vertical transport by observing its spatial and temporal distribution characteristics. The Hong Kong Observatory has been operating an environmental radiation monitoring programme for decades, and long record of Be-7 activity concentration data in airborne particulate samples are available to characterize the behaviour of Be-7 in the lower atmosphere in Hong Kong. In this study, Be-7 activity concentration data of airborne particulates collected at three locations in Hong Kong from 1993 to 2020 are examined. Temporal variations are analyzed. In particular, the long-term monthly average Be-7 activity concentrations are found to be most sensitive to precipitation. The relevant data analysis, as well as key factors affecting the Be-7 activity concentrations in the lower atmosphere in Hong Kong, will be described.