3 research outputs found
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/m<sup>3</sup> (0.013 pg/L),
0.26 μBq/m<sup>3</sup> (0.010 fg/L), 23 μBq/m<sup>3</sup> (0.010 fg/L), 84 μBq/m<sup>3</sup> (0.010 fg/L) and 0.6 mBq/m<sup>3</sup> (0.048 ng/L) for <sup>99</sup>Tc, <sup>237</sup>Np, <sup>239</sup>Pu, <sup>240</sup>Pu and <sup>238</sup>U 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 <sup>129</sup>I 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 <sup>129</sup>I and <sup>127</sup>I, including
organic forms; it was observed that <sup>129</sup>I/<sup>127</sup>I atomic ratios in the Antarctic surface seawater ((6.1–13)
× 10<sup>–12</sup>) are about 2 orders of magnitude lower
than those in the Antarctic snow ((6.8–9.5) × 10<sup>–10</sup>), but 4–6 times higher than the prenuclear level (1.5 ×
10<sup>–12</sup>), indicating a predominantly anthropogenic
source of <sup>129</sup>I in the Antarctic environment. The <sup>129</sup>I 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 <sup>129</sup>I in Antarctic snow mainly originates
from atmospheric nuclear weapons testing from 1945 to 1980; resuspension
and re-emission of the fallout <sup>129</sup>I in the Southern Hemisphere
maintains the <sup>129</sup>I level in the Antarctic atmosphere. <sup>129</sup>I directly released to the atmosphere and re-emitted marine
discharged <sup>129</sup>I 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 <sup>129</sup>I in seawater depth profiles collected
offshore Fukushima in June 2011. Significantly elevated <sup>129</sup>I concentrations in surface water were observed with the highest <sup>129</sup>I/<sup>127</sup>I atomic ratio of 2.2 × 10<sup>–9</sup> in the surface seawater 40 km offshore Fukushima. Iodide was found
as the dominant species of <sup>129</sup>I, while stable <sup>127</sup>I was mainly in iodate form, reflecting the fact that the major source
of <sup>129</sup>I is the direct liquid discharges from the Fukushima
NPP. The amount of <sup>129</sup>I 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 <sup>129</sup>I 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 <sup>129</sup>I from the Fukushima
accident was estimated. These Fukushima-derived <sup>129</sup>I data
provide necessary information for the investigation of water circulation
and geochemical cycle of iodine in the northwestern Pacific Ocean
in the future