222RN at Bermuda and Mauna Loa: Local and distant sources

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Continuous measurements of atmospheric222Rn were made for the past three years by the Environmental Measurements Laboratory (EML) at the Atmosphere/Ocean Chemistry Experiment site located at Tudor Hill, Bermuda and at the National Oceanic and Atmospheric Administration/Climate Monitoring and Diagnostics Laboratory Mauna Loa Observatory. The222Rn analyzer is based on the two-filter tube method. At the Bermuda site, monthly median222Rn concentration range from ∼50 to 700 mBq m-3, and the concentrations vary seasonally, with a maximum in the winter and a minimum in the summer. The concentrations are significantly elevated when local winds traverse the island. At MLO, monthly median222Rn concentrations range from ∼ 100 mBq m-3 during the fall months to ∼ 400 mBq m-3 during the spring months. The springtime maximum values correspond to periods of rapid transport in the free troposphere from the Asian continent, corroborated by backward air mass trajectories. The222Rn data are also used to help decipher local daily upslope/downslope conditions present at MLO. This study illustrates the value of atmospheric222Rn monitoring, when screened through the filter of local meteorology, in studying the transport of continental air to the oceans, as well as the dynamics of local meteorological effects. © 1995 Akadémiai Kiadó.

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Journal of Radioanalytical and Nuclear Chemistry Articles