Full range determination of 222Rn at the watershed scale by liquid scintillation counting

222Rn has been increasingly used to identify groundwater contribution to surface water. Particular attention has been paid to analytical protocols and counting parameters used for liquid alpha scintillation measurements over a range of activities covering river and groundwater domains. Direct measurements and Rn-extraction protocols are optimized, and scintillometer efficiency is calibrated using international standards over the 0.5–35 Bq/L range. The interval of activities was performed in surface water and groundwater from a small Canadian watershed.

► Several analytical tests were developed to optimize protocols for 222Rn measurements in water.
► Two analytical procedures, direct and extraction methods were found in order to guarantee a 0.5–35 Bq/L range of measurement.
► A specific test has been conducted to evidence that both methods are well calibrated.
► Those protocols have been tested on water from a small Canadian watershed.