3,000 Table t Excess radon . aw H4 2,000 + cay Of tadon 4 Liquid tquid id rem emove , . Decay of RaA 3 x S 1,000; T 0 — |at30 days) Spas *Vichy Celestin Juventus *Vichy Catalan 48-5 45°5 43-3 — — — 3,150 1,250 1,700 16:4 36-4 25-5 Llandrindod 26-2 . *Perrier 10 20 30 Hours after sealing liquid sample . 40 Penzance Penzance thorium series, such as thorium-228 (radiothorium- 228), at comparable levels of activity, the initial thorium series activity of these waters is regarded as due to radium-224 and its daughters. These values are given in Table 3 corrected for decay ofactivity since time of sampling. In a numberof the waters having very low activity it has not been possible to determine either the level of radium-224 or of the lIong-lived members of the thorium series. In a few specimens having intermediate values of long-lived «-aetivity, the presence of thorium-228 and its daughters has been observed but at levels representing small fractions of the total long-lived a-activities given in Table I. Results The values of long-lived a-activity together with the activities due to excess radon-222 and its daughters are given in Table 1 for various categories of water. In a number of instances waters from more than one source have been measured for a given town, and these are listed separately. Ground-waters have been divided into two groups comprising those derived from boreholes in chalk and those from boreholes in other geological strata. Surface waters include sources such as springs, rivers, lakes and reservoirs. Column 4 of Table 1 gives the content of solid matter observed (in parts per million), and column 5 the long-lived «-activity of this residue 30 days after evaporation of the liquid specimen. Table 2 indicates the range of values and mean long-lived «-activity for the different categories of water and their residues. In Table 3 the total a-activity of a number of the more active samples is broken down into its three main components. Discussion It will be seen from Tables | and 2 that the highest values of long-lived a-activity are found in the group of spa waters, which possess high contents of mineral matter having specific activities greater than those 2 1 St. Ives Fig. 3 in a numberof our specimens is due to the presence of radium-224 and its daughters in the freshly sampled waters. In the absence of long-lived members of the 1 3 2 1 1,000-2,000 16°7 200-300 Penzance Camborne Camborne 3 1 2 1 200-300 4:5 2:2 1,500—2,0U0 —_ 2,540 3,320 10,200 (uue./gm. 14-7 7-9 1-7 — 210 675 370 21°5 3-3 9-40 4-10 2:20 1:41 9,000-10,000 600 100-200 1,000-2,000 163 170 125 83 57-6 24:1 17-6 17-0 1-00 9,000~10,000 42 1:24 1:02 2 sampling) 37-0 1:8 St.ives Helston Helston Helston sans of residue million) Buxton *Vittel + _ a-Activity (parts per Cornish waters 0 Solid matter observed at time of Bath Decay of RaB+RaC (4zc./litre {uuc./litre Leamington / “tt a-activity at30days)| & me 33 Long-lived and daughters; Origin 700-800 160-200 0-90 0-59 0-46 500-600 4,000—5,000 4,000—5 000 54 7 133 33 3 4-8 23-0 14-6 23-8 6-8 7-1 92-0 * Ground-watcrs (not chalk strata) Bristol 1 Wolverhampton: Bristol 2 Leamington Spalding Hartlepools Ashford (Kent) Cirencester 2 South Staffs 1 Ground-waters (chalk strata) London 1 Uxbridge Canterbury Sutton (Surrey) Ashford. (Kent) Portsmouth Colne Vailey Amersham i Barnet 2-90 300-400 1,230 24 2°28 1:75 —_— 600-700 73 300 8-4 5-8 1:34 $-00 100-200 100-200 360 38U 3:7 2-6 0-58 0°33 ~ 10 —_— 210 zou 133 2-8 1-22 0°65 0:30 — — —_ 380 216 234 3°2 3-0 1:3 0-27 10-20 100 2:7 0-26 _— 200 1-60 O-3F 1 0-23 0-22 0-22 - — 100-200 — 420 3:8 2:8 1-3 1:3 209 360 217 1-1 0-5 i-d 100-200 200 0-11 0-11 —_ —_ 125 188 a9 0-6 1 4 3 2 0:81 0-62 0:52 0:47 0-41 100-200 300-400 50-100 — —_ 370 240 158 380 284 244 30 25 2:2 2°6 3:3 1:2 1:5 1-4 13:1 12-0 Festiniog Skipton Aberdeen Manchester 1 Charminster Dundee Torquay Edinburgh Aberystwyth Glasgow Glamorgan 2 0-20 0-20 0:14 0-12 0-11 0-11 0:11 0:10 0:10 0-09 0-09 —_— <i —_ — — <i <l <i — — — _ 380 42 54 96 33 55 33 —_ — 33 _ 2-5 3:3 2-2 1-2 3°'3 2-0 3-0 —_ _ 2-7 South Staffs 2 0-08 — 208 _ —_— 33 29 0-03 — —_ — —_ — 5 _ 21 30 —_ —_ 0-03 —_ _ _— Farnham Common Brighton Surface waters Bristol Glamorgan Bristol London London Bath Belfast Paignton Blaenau Sheffield Hamilton Birmingham Manchester 2 Argyit Flan Valley Caernarvon Manchester 3 Dolgelley Bangor Betws-yCoed Hazleton 0-19 100-200 0-33 0°38 Q-30 0-09 10-20 —_— _ —_ 0-08 <i 0-05 <1 0-07 0-05 0-04 0-04 0-04 0:08 0-02 _ 54 1:7 0:4 38 21 15 3:3 _ * Bottled specimens as purchased 1:0 2-1 1-7 3-0 _— 1:9 1-0 —