TY - JOUR

T1 - Disproportionately High Contributions of 60 Year Old Weapons-137Cs Explain the Persistence of Radioactive Contamination in Bavarian Wild Boars

AU - Stäger, Felix

AU - Zok, Dorian

AU - Schiller, Anna Katharina

AU - Feng, Bin

AU - Steinhauser, Georg

N1 - Funding Information: The authors are indebted to Joachim Reddemann, the Bavarian Hunting Association (BJV), and the many Bavarian hunters who supported this study with samples and interesting discussions. We thank Dieter Swart for provision of the data used in Figures S3 and S4 and Martin Steiner from BfS for the Cs inventory data for Bavaria. Financial support by the Bavarian Academy for Hunting and Nature is gratefully acknowledged. B.F. thanks the Alexander von Humboldt Foundation for a postdoctoral fellowship. Some graphics used in Figure 5 were designed by Freepik and provided by the Media Library of University of Maryland Center for Environmental Science, respectively. 137

PY - 2023/9/12

Y1 - 2023/9/12

N2 - Radionuclides released from nuclear accidents or explosions pose long-term threats to ecosystem health. A prominent example is wild boar contamination in central Europe, which is notorious for its persistently high 137Cs levels. However, without reliable source identification, the origin of this decades old problem has been uncertain. Here, we target radiocesium contamination in wild boars from Bavaria. Our samples (2019-2021) range from 370 to 15,000 Bq·kg-1137Cs, thus exceeding the regulatory limits (600 Bq·kg-1) by a factor of up to 25. Using an emerging nuclear forensic fingerprint, 135Cs/137Cs, we distinguished various radiocesium source legacies in their source composition. All samples exhibit signatures of mixing of Chornobyl and nuclear weapons fallout, with 135Cs/137Cs ratios ranging from 0.67 to 1.97. Although Chornobyl has been widely believed to be the prime source of 137Cs in wild boars, we find that “old” 137Cs from weapons fallout significantly contributes to the total level (10-68%) in those specimens that exceeded the regulatory limit. In some cases, weapons-137Cs alone can lead to exceedances of the regulatory limit, especially in samples with a relatively low total 137Cs level. Our findings demonstrate that the superposition of older and newer legacies of 137Cs can vastly surpass the impact of any singular yet dominant source and thus highlight the critical role of historical releases of 137Cs in current environmental pollution challenges.

AB - Radionuclides released from nuclear accidents or explosions pose long-term threats to ecosystem health. A prominent example is wild boar contamination in central Europe, which is notorious for its persistently high 137Cs levels. However, without reliable source identification, the origin of this decades old problem has been uncertain. Here, we target radiocesium contamination in wild boars from Bavaria. Our samples (2019-2021) range from 370 to 15,000 Bq·kg-1137Cs, thus exceeding the regulatory limits (600 Bq·kg-1) by a factor of up to 25. Using an emerging nuclear forensic fingerprint, 135Cs/137Cs, we distinguished various radiocesium source legacies in their source composition. All samples exhibit signatures of mixing of Chornobyl and nuclear weapons fallout, with 135Cs/137Cs ratios ranging from 0.67 to 1.97. Although Chornobyl has been widely believed to be the prime source of 137Cs in wild boars, we find that “old” 137Cs from weapons fallout significantly contributes to the total level (10-68%) in those specimens that exceeded the regulatory limit. In some cases, weapons-137Cs alone can lead to exceedances of the regulatory limit, especially in samples with a relatively low total 137Cs level. Our findings demonstrate that the superposition of older and newer legacies of 137Cs can vastly surpass the impact of any singular yet dominant source and thus highlight the critical role of historical releases of 137Cs in current environmental pollution challenges.

KW - cesium isotopes

KW - contaminant persistence

KW - environmental radioactivity

KW - nuclear forensics

KW - wild boar

UR - http://www.scopus.com/inward/record.url?scp=85170717333&partnerID=8YFLogxK

U2 - 10.1021/acs.est.3c03565

DO - 10.1021/acs.est.3c03565

M3 - Article

C2 - 37646445

AN - SCOPUS:85170717333

VL - 57

SP - 13601

EP - 13611

JO - Environmental Science and Technology

JF - Environmental Science and Technology

SN - 0013-936X

IS - 36

ER -