2000 Volume 1 Issue 1 Pages 5-10
The distributions of the naturally occurring radionuclides 238U, 234U, 232Th, 230Th, 228Th, 228Ra, and 226Ra in river and hot spring water within the Peitou hot spring basin at the northern part of Taiwan were studied by using alph-and gamma-spectrometric methods and liquid scintillation counting method. The respective concentration ranges of 238U, 234U, 232Th, 230Th, 228Th, and 226Ra in river and hot spring water were 0.80-48, 1.2-51, 0.05-44, 0.09-39, 0.19-342, 3.0-22.5 mBq/L and 2.3-85, 2.9-91, 0.67-73, 1.14-66, 1.01-630, and 4. 5-36.5 mBq/L, respectively. In general, the distributions of uranium-series and thorium-series nuclides in river water, hot spring water were all pH dependent. The respective radioactivity ratios of 234U/238U in river and hot spring water are observed to be 1. 0-1.5 and 1.03-1.5, however, the radioactivity ratios of 228Th/232Th in river and hot spring water are 1.4-19 and 1.5-8.8, respectively. The high 228Th/232Th activity ratios showed that besides the recoil effect, enrichment of 228Ra to 232Th in the waters was another possible factor causing an excess of 228Th. Because radium may exist as (Pb, Ba, Ra) (SO4) x pseudo-colloid in hot spring water, which is the same as the more famous mineral of Peitoustone (Hukutolite), therefore, 228Ra and 226Ra are more abundant in the hot spring sediments, which radioactivity arel8-3010 and 16-230 Bq/kg (dry), respectively.