Hourly concentratons of Rn-222 in air samled from the inlet (12.5m asl) on the fromt mast and in sea water sampled from the depth of 4.5 m. In the data processing, recalibration of the radon detectors was made. Erronous data were also excluded by judging from the flow rate and humidity of air through the radon monitors.
The high-sensitivity radon monitor used is of a electrostaic type with a vessel volume of 70 L, in which Rn-222 atoms in the sample air decays into Po-218 atoms to be collected onto a negactively charged electrode. Alfa particles emitted from Po-218 and its decay products are detected nenergy-sensiteve PIN photodiode to determine Rn-222 concentration.
An EXCEL file containing a self-explanatory table of time seris data