Rapid Multisample Analysis for Simultaneous Determination of Anthropogenic Radionuclides in Marine Environment

An automated multisample processing flow injection (FI) system was developed for simultaneous determination of technetium, neptunium, plutonium, and uranium in large volume (200 L) seawater. Ferrous hydroxide coprecipitation was used for the preliminary sample treatment providing the merit of simultaneous preconcentration of all target radionuclides. Technetium was separated from the actinides via valence control of technetium (as Tc­(VII)) in a ferric hydroxide coprecipitation. A novel preseparation protocol between uranium and neptunium/plutonium fractions was developed based on the observation of nearly quantitative dissolution of uranium in 6 mol/L sodium hydroxide solution. Automated extraction (TEVA for technetium and UTEVA for uranium) and anion exchange (AGMP-1 M for plutonium and neptunium) chromatographic separations were performed for further purification of each analyte within the FI system where four samples were processed in parallel. Analytical results indicate that the proposed method is robust and straightforward, providing chemical yields of 50–70% and improved sample throughput (3–4 d/sample). Detection limits were 8 mBq/m³ (0.013 pg/L), 0.26 μBq/m³ (0.010 fg/L), 23 μBq/m³ (0.010 fg/L), 84 μBq/m³ (0.010 fg/L) and 0.6 mBq/m³ (0.048 ng/L) for ⁹⁹Tc, ²³⁷Np, ²³⁹Pu, ²⁴⁰Pu and ²³⁸U for 200 L seawater, respectively. The unique feature of multiradionuclide and multisample simultaneous processing vitalizes the developed method as a powerful tool in obtaining reliable data with reduced analytical cost in both radioecology studies and nuclear emergency preparedness

Iodine-129 in Snow and Seawater in the Antarctic: Level and Source

Anthropogenic ¹²⁹I has been released to the environment in different ways and chemical species by human nuclear activities since the 1940s. These sources provide ideal tools to trace the dispersion of volatile pollutants in the atmosphere. Snow and seawater samples collected in Bellingshausen, Amundsen, and Ross Seas in Antarctica in 2011 were analyzed for ¹²⁹I and ¹²⁷I, including organic forms; it was observed that ¹²⁹I/¹²⁷I atomic ratios in the Antarctic surface seawater ((6.1–13) × 10^–12) are about 2 orders of magnitude lower than those in the Antarctic snow ((6.8–9.5) × 10^–10), but 4–6 times higher than the prenuclear level (1.5 × 10^–12), indicating a predominantly anthropogenic source of ¹²⁹I in the Antarctic environment. The ¹²⁹I level in snow in Antarctica is 2–4 orders of magnitude lower than that in the Northern Hemisphere, but is not significantly higher than that observed in other sites in the Southern Hemisphere. This feature indicates that ¹²⁹I in Antarctic snow mainly originates from atmospheric nuclear weapons testing from 1945 to 1980; resuspension and re-emission of the fallout ¹²⁹I in the Southern Hemisphere maintains the ¹²⁹I level in the Antarctic atmosphere. ¹²⁹I directly released to the atmosphere and re-emitted marine discharged ¹²⁹I from reprocessing plants in Europe might not significantly disperse to Antarctica

Iodine-129 in Seawater Offshore Fukushima: Distribution, Inorganic Speciation, Sources, and Budget

The Fukushima nuclear accident in March 2011 has released a large amount of radioactive pollutants to the environment. Of the pollutants, iodine-129 is a long-lived radionuclide and will remain in the environment for millions of years. This work first report levels and inorganic speciation of ¹²⁹I in seawater depth profiles collected offshore Fukushima in June 2011. Significantly elevated ¹²⁹I concentrations in surface water were observed with the highest ¹²⁹I/¹²⁷I atomic ratio of 2.2 × 10^–9 in the surface seawater 40 km offshore Fukushima. Iodide was found as the dominant species of ¹²⁹I, while stable ¹²⁷I was mainly in iodate form, reflecting the fact that the major source of ¹²⁹I is the direct liquid discharges from the Fukushima NPP. The amount of ¹²⁹I directly discharged from the Fukushima Dai-ichi nuclear power plant to the sea was estimated to be 2.35 GBq, and about 1.09 GBq of ¹²⁹I released to the atmosphere from the accident was deposited in the sea offshore Fukushima. A total release of 8.06 GBq (or 1.2 kg) of ¹²⁹I from the Fukushima accident was estimated. These Fukushima-derived ¹²⁹I data provide necessary information for the investigation of water circulation and geochemical cycle of iodine in the northwestern Pacific Ocean in the future