11 research outputs found
Vertical Distributions of Radionuclides (<sup>239+240</sup>Pu, <sup>240</sup>Pu/<sup>239</sup>Pu, and <sup>137</sup>Cs) in Sediment Cores of Lake Bosten in Northwestern China
Artificial
radionuclides (<sup>137</sup>Cs, <sup>239+240</sup>Pu, <sup>241</sup>Pu, <sup>241</sup>Am) deposited in lacustrine sediments
have been used for dating as well as radionuclide source identification.
In the present work, we investigated the vertical distributions of <sup>239+240</sup>Pu and <sup>137</sup>Cs activities, <sup>240</sup>Pu/<sup>239</sup>Pu atom ratios, and <sup>239+240</sup>Pu/<sup>137</sup>Cs
activity ratios in sediment cores collected from Lake Bosten, which
is the lake closest to the Lop Nor Chinese Nuclear Weapon Test site
in northwestern China. Uniformly high concentrations of <sup>239+240</sup>Pu and <sup>137</sup>Cs were found in the upper layers deposited
since 1964 in the sediment cores, and these were controlled by the
resuspension of soil containing radionuclides from the nearby land
surface. As the Chinese nuclear tests varied remarkably in yield,
the mixing of the tropospheric deposition from these tests and the
stratospheric deposition of global fallout has led to a <sup>240</sup>Pu/<sup>239</sup>Pu atom ratio that is similar to that of global
fallout and to a <sup>239+240</sup>Pu/<sup>137</sup>Cs activity ratio
that is slightly higher than that of global fallout. However, a low <sup>240</sup>Pu/<sup>239</sup>Pu atom ratio of 0.080 and high <sup>239+240</sup>Pu/<sup>137</sup>Cs activity ratio of 0.087, significantly different
from the global fallout values, were observed in one sediment core
(07BS10-2), indicating the inhomogenous tropospheric deposition from
the Chinese nuclear tests in Lake Bosten during 1967–1973.
These results are important to understand the influence of the CNTs
on the radionuclide contamination in Lake Bosten
Peroxygenase activity of OxdAs (WT and H320D).
<p>Peroxygenase activity of OxdAs (WT and H320D).</p
Analyses of peroxidase activities of OxdAs in the presence of ABTS.
<p>(A) The peroxidase activities of OxdAs depending on the H<sub>2</sub>O<sub>2</sub> concentration. OxdA(WT) [(a) black circles], OxdA(H320D) [(a) black triangles], and OxdA(H320A) [(b) black square]. (B) Michaelis—Menten kinetics of the peroxidase activity of OxdAs. OxdA(WT) (a), OxdA(H320D) (b) and OxdA(H320A) (c). The reactions with ABTS as a substrate were carried out under the “standard assay C” conditions as described under “Materials and Methods.” For all data points, values are means ± mean error.</p
Peroxidase activity of OxdAs using guaiacol as a substrate.
<p>Peroxidase activity of OxdAs using guaiacol as a substrate.</p
Peroxidase activity of OxdAs using ABTS as a substrate.
<p>Peroxidase activity of OxdAs using ABTS as a substrate.</p
Analyses of peroxidase activities of OxdAs in the presence of guaiacol.
<p>(A) The peroxidase activities of OxdAs depending on the H<sub>2</sub>O<sub>2</sub> concentration. OxdA(WT) [(a) black circles], OxdA(H320D) [(a) black triangles], and OxdA(H320A) [(b) black square]. (B) Michaelis—Menten kinetics of the peroxidase activity of OxdAs. OxdA(WT) (a), OxdA(H320D) (b) and OxdA(H320A) (c). The reactions with guaiacol as a substrate were carried out under the “standard assay B” conditions as described under “Materials and Methods.” For all data points, values are means ± mean error.</p
Michaelis—Menten kinetics of the catalase activity of OxdAs.
<p>The reactions were carried out under the “standard assay A” conditions as described under “Materials and Methods.” For all data points, values are means ± mean error. OxdA(WT) (A), OxdA(H320D) (B) and OxdA(H320A) (C).</p
Catalase activity of OxdAs (WT, H320D and H320A).
<p>Catalase activity of OxdAs (WT, H320D and H320A).</p
Contribution of radionuclide to dose rate estimated on expressway from Fukushima Prefecture to Aomori Prifecture.
<p>*FNPS: Fukshima Dai-ichi Nuclear Power Station.</p
Cumulative individual radiation dose accumulated daily.
<p>The survey teams have started measuring our departure from Hirosaki.</p