A worldwide meta-analysis (1977–2020) of sediment core dating using fallout radionuclides including <sup>137</sup>Cs and <sup>210</sup>Pb<sub>xs</sub>

Abstract

Abstract. Dating recent sediment archives (< 150 years) constitutes a prerequisite for environmental and climatic reconstructions. Radiocaesium (137Cs) emitted during thermonuclear bomb testing (~1950 ̶ 1980) and nuclear accidents, as well as the decrease of excess lead-210 (210Pbxs) with depth are often combined to establish sediment core chronology. Although these methods have been widely used during the last several decades, there is a lack of structured and comprehensive worldwide synthesis of fallout radionuclide analyses used for dating sediment cores in environmental and Earth sciences. The current literature overview was based on the compilation of 573 articles published between 1977 and 2020, reporting the collection of 1351 individual dating sediment cores (the dataset can be accessed at https://doi.pangaea.de/10.1594/PANGAEA.931493). This review was conducted in order to map the locations where 137Cs fallout events were detected. These included the thermonuclear bomb testing peak in 1963, the Chernobyl accident in 1986, the Fukushima accident in 2011, and 24 additional events identified in 112 sites that led to local radioactive releases (e.g. Sellafield accidents, Chinese nuclear tests). When 210Pbxs records were used along with 137Cs data, detailed information on the 210Pbxs age depth models were also synthesized. Multiple information including the core collection method, sediment properties, radionuclide analysis techniques and catchment characteristics were also compiled. With the current growing number of studies analyzing sediment cores and the increasing interest in the deployment of sediment fingerprinting techniques including radionuclides as potential discriminant properties, this spatialized synthesis provides a unique worldwide compilation for characterizing fallout radionuclide sources and levels at the global scale. This synthesis provides in particular a referential of 137Cs peak attribution for improving the sediment core dating and it outlines the main questions that deserve attention in future research as well as the regions where additional 137Cs fallout investigations should be conducted in priority.

Drivers of 20th century sea‐level change in southern New Zealand determined from proxy and instrumental records

“…137 Cs concentrations, however, reach a clear peak at 0.065 m depth (Fig. 5b), which we attribute to 1965 CE, allowing 2 years for interhemispheric mixing and full atmospheric homogenization in the Southern Hemisphere (Hancock et al, 2011;Gehrels et al, 2012;Foucher et al, 2021). Changes in the 206 Pb/ 207 Pb curve are less pronounced than at Pounawea (Gehrels et al, 2008) or in Tasmania (Gehrels 2.…”

Delayed inputs of hot 137Cs and 241Am particles from Chernobyl to sediments from three Finnish lakes: implications for sediment dating

“…Artificial radionuclides such as 137 Cs and 241 Am play an important role in dating lake sediments, and the wide range of environmental records they contain. Matches between well dated features in the 137 Cs (or 241 Am) fallout record and clearly identifiable features in the activity versus depth record are used to date specific sediment layers (Foucher et al 2021). Although of limited value on their own, these chronostratigraphic dates play an important role in validating the more detailed chronologies obtained from 210 Pb records, or correcting 210 Pb dates in the event of any discrepancies (Appleby 2001).…”