Determination of99Tc in coastal seawater collected in Fukuoka, Japan

Vertical distributions of 99Tc and the 99Tc/137Cs activity ratio in the coastal water off Aomori, Japan

“…The 99 Tc concentration and the activity ratios of 99 Tc/ 137 Cs in surface water ranged from 1.8 to 2.4 mBq/m 3 and 10.2 Â 10 À4 to 12.0 Â 10 À4 , respectively. The 99 Tc concentrations in surface water in this work were comparable to those measured previously in the coastal waters off Fukuoka Prefecture, Japan (1.0e7.4 mBq/m 3 : Momoshima et al, 1995) and in the Pacific Ocean (0.5e3.3 mBq/m 3 : Momoshima et al, 2005). Table 4 shows the compilation of previous reports for 99 Tc concentrations and 99 Tc/ 137 Cs activity ratios in surface seawater.…”

“…The activity ratios of 99 Tc/ 137 Cs in surface water were 2.5e3 times higher than the ratio predicted from fission yield, 4.1 Â 10 À4 in 2007, with a correction for radioactive decay (Momoshima et al, 1995). Much higher 99 Tc/ 137 Cs activity ratios have been reported in seawater in Europe under the influence of radioactive liquid discharge from reprocessing plants (Holm et al, 1988;Brown et al, 2002;Lindahl et al, 2003: Table 4).…”

“…The 99 Tc concentrations around the Japanese Islands were significantly lower compared to those found at the eastern coastal region in the North Atlantic, where seawater is contaminated with liquid effluent released from the spent nuclear fuel reprocessing plants in Europe (Holm et al, 1988;Lindahl et al, 2003). Momoshima et al (1995Momoshima et al ( , 2005 suggested that 99 Tc in the coastal waters off Fukuoka and in the Pacific Ocean was derived only from global fallout. The low 99 Tc concentrations observed in this work were also at the global fallout level, even though the reprocessing plant at Aomori Prefecture has started test operation.…”

“…The reported background data of 99 Tc in surface seawater are limited (Dahlgaard et al, 1995;Momoshima et al, 1995Momoshima et al, , 2005. Moreover, its vertical distribution is not available because of its very low radioactivity in seawater, so that several thousand liters of seawater are required for only a single determination.…”

Hydrologic and Geochemical Controls on the Transport of Radionuclides in Natural Undisturbed Arid Environments as Determined by Accelerator Mass Spectrometry Measurements

“…Garcia-Leon et al (1993) observed ~0.1 mBq/L in pre-Chernobyl rain in Spain. In comparison, ocean samples have been measured in the range 0.001 mBq/L (Momoshima et al, 1995) to 0.06 mBq/L (Holm, 1993).…”