| Summary: | 碩士 === 國立清華大學 === 物理學系 === 92 === Abstract
Hokutolite, a sediment on Andesite, is a radiative mineral. At present it is only found at Peitou Hot Spring in Taiwan and Tamagawa Hot Spring in Japan. The main composition of Hokutolite is a solid solution of barium sulfate and lead sulfate. Previous studies have shown that the weight ratio of Ba to Pb in Hokutolite from Taiwan is either 0.6-1.8 or 1.5-2.5. On the contrary, the weight ratio of Ba to Pb in Hokutolite from Japan is about 3.7-3.8.
Using Particle Induced X-ray Emission, we obtained that the weight ratio of Ba and Pb in Hokutolite from Taiwan is about 0.7-1.45. However, Andesite and “Artificial Hokutolite” (Andesite sunk in Peito Hot Spring for one and a half months) are also be analyzed. The Ba/Pb weight ratio of Andesite and “Artificial Hokutolite” are 0.23 and 0.32, respectively. Thus, we hypothesize that Hokutolite has started to deposit on the “Artificial Hokutolite” in the month and half of our experiment.
In addition, we analyzed theγ-ray of radionuclide 224Ra in the water issuing from the source and downstream. The radioactivities at these two locations are 3.5Bq/L and1.1Bq/L, respectively. From this we estimate that the Hot Spring is diluted to about 1/3 by domestic sewage and rainfall.
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