Citation

Hain K, Steier P, Froehlich MB, Golser R, Hou X, Lachner J, Nomura T, Qiao J, Quinto F, Sakaguchi A. Nat. Commun. 2020; 11(1): e1275.

Affiliation

Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan.

Copyright

(Copyright © 2020, Holtzbrinck Springer Nature Publishing Group)

DOI

10.1038/s41467-020-15008-2

PMID

32152279

Abstract

Isotopic ratios of radioactive releases into the environment are useful signatures for contamination source assessment. Uranium is known to behave conservatively in sea water so that a ratio of uranium trace isotopes may serve as a superior oceanographic tracer. Here we present data on the atomic [Formula: see text]U/[Formula: see text]U ratio analyzed in representative environmental samples finding ratios of (0.1-3.7)[Formula: see text]10[Formula: see text]. The ratios detected in compartments of the environment affected by releases of nuclear power production or by weapons fallout differ by one order of magnitude. Significant amounts of [Formula: see text]U were only released in nuclear weapons fallout, either produced by fast neutron reactions or directly by [Formula: see text]U-fueled devices. This makes the [Formula: see text]U/[Formula: see text]U ratio a promising new fingerprint for radioactive emissions. Our findings indicate a higher release of [Formula: see text]U by nuclear weapons tests before the maximum of global fallout in 1963, setting constraints on the design of the nuclear weapons employed.

Language: en