Radon measurement in karstic waters with Lucas cell technique

Based on Lucas cell technique, the portable device named "PRASSI" (SILENA m od. 5S) was used to realise discrete radon measurements in water samples. T he calibration factor is (64.7 +/- 6.9) cpm . Bq(-1) and, with the present set-up for measuring radon in water, the detection and the determination li mits are, respectively, 0.007 and 0.020 Bq. Thus, the device is well adapte d for determining low radon content in karstic waters. Several discrete rad on samplings were performed nearly every week in the three main springs of the Bastareny karstic system (Catalonian Pyrenees, N-E Spain). Thus, it was possible to estimate the reproducibility of the methodology as well as to characterise every spring of the aquifer in relation to their hydrogeologic al features. With the portable radon monitor, some useful measurements were achieved to estimate radon loss due to degassing process over short distan ces, with important consequences for radon studies in karstic waters. Lastl y, it was possible to perform intensive sampling during a flood and the res ults point out the great variability of radon levels, closely related to th e flow rate trend. That permitted also an intercomparison with other radon probes installed previously in every spring, for continuous radon measureme nts.