The 240Pu/239Pu atom ratio in Chinese soils

Yanan Huang; Stephen G Tims; Michaela B Froehlich; Shaoming Pan; L Keith Fifield; Stefan Pavetich; Dominik Koll

doi:10.1016/j.scitotenv.2019.04.251

The ²⁴⁰Pu/²³⁹Pu atom ratio in Chinese soils

Sci Total Environ. 2019 Aug 15:678:603-610. doi: 10.1016/j.scitotenv.2019.04.251. Epub 2019 Apr 19.

Authors

Yanan Huang¹, Stephen G Tims², Michaela B Froehlich³, Shaoming Pan⁴, L Keith Fifield³, Stefan Pavetich³, Dominik Koll³

Affiliations

¹ The key Laboratory of Coastal and Island Development of Ministry of Education, School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing 210023, PR China; Department of Nuclear Physics, Research School of Physics and Engineering, The Australian National University, Canberra 2601, ACT, Australia.
² Department of Nuclear Physics, Research School of Physics and Engineering, The Australian National University, Canberra 2601, ACT, Australia. Electronic address: steve.tims@anu.edu.au.
³ Department of Nuclear Physics, Research School of Physics and Engineering, The Australian National University, Canberra 2601, ACT, Australia.
⁴ The key Laboratory of Coastal and Island Development of Ministry of Education, School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing 210023, PR China. Electronic address: span@nju.edu.cn.

PMID: 31085490
DOI: 10.1016/j.scitotenv.2019.04.251

Abstract

The ²⁴⁰Pu/²³⁹Pu atom ratio is a very effective tool for the identification of the origin of plutonium (Pu) in the soil environment. We examine a dataset of ²⁴⁰Pu/²³⁹Pu atom ratios determined from surface and core soils at 240 sites across China. The data were compiled from 18 separate literature sources from the last 20 years. For the first time the spatial distribution (3 latitude bands and 7 natural regions) of the weighted average ²⁴⁰Pu/²³⁹Pu atom ratios in Chinese soils is investigated. An area to the West of Xining City, shows a weighted average ²⁴⁰Pu/²³⁹Pu atom ratio of 0.167 ± 0.002, lower than that of average global fallout, which likely arises from the addition of local fallout radionuclides from the Chinese nuclear weapon tests at Lop Nor between 1964 and 1980. The Yumen and Jiuquan areas of Northwest China in particular show evidence of very low ratio material from the Chinese nuclear weapon tests. Excluding the impacted area around the test site the weighted average ²⁴⁰Pu/²³⁹Pu ratio of 0.182 ± 0.002 suggests that global fallout is the main source of Pu in most Chinese soils.

Keywords: (240)Pu/(239)Pu; China; Plutonium isotopes; Soil.