Radioactive disequilibrium of uranium and thorium nuclide series in river waters from the Ta-Tun volcanic group area in Taiwan

摘要: Alpha spectrometry and liquid scintillation counting were used in this study to analyze the radioactivities of naturally occurring radionuclides, 238U, 234U, 232Th, 230Th, 228Th 226Ra, river waters from Ta-Tun volcanic group area Northern Taiwan. The respective concentration range 226Ra was 0.80–48, 1.2–51, 0.05–44, 0.09–39, 0.19–342 3.0–22.5 mBq L−1 234U/238U 228Th/232Th activity ratios greater than 1, indicating radioactive disequilibrium waters. high showed that besides recoil effect, enrichment 228Ra 232Th another possible factor causing an excess 228Th. concentrations uranium thorium changed with pH water. U/Th ratio about 1; acidic (pH < 5) samples; whereas it much higher 1 neutral ∼ 7) samples.