Continental-scale impact of bomb radiocarbon affects historical fossil fuel carbon dioxide reconstruction

<b>Source data underlying the figures and tables presented in the paper:</b><b>Continental-scale impact of bomb radiocarbon affects historical fossil fuel carbon dioxide reconstruction</b>Jing Li¹, Nannan Wei², Xu Wang³*, Pingyang Li¹, Yanmin Sun¹, Wenbiao Feng¹, Zhineng Cheng¹, Sanyuan Zhu¹, Weimin Wang⁴, Duohong Chen⁵, Shizhen Zhao¹, Guangcai Zhong¹, Guangyi Zhou², Jun Li¹, and Gan Zhang¹*¹State Key Laboratory of Advanced Environmental Technology, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China² School of Nuclear Science and Technology, University of South China, Hengyang 421001, China³Tropical Forestry Research Institute, Chinese Academy of Forestry, China, Guangzhou, Guangdong, 510520⁴Shenzhen Ecological and Environmental Monitoring Center of Guangdong Province<i>, </i>Shenzhen 518049<i>, </i>China⁵Environmental Key Laboratory of Regional Air Quality Monitoring, Ministry of Ecology and Environment, Guangdong Ecological and Environmental Monitoring Center, Guangzhou 510308, China^* Correspondence to: Gan Zhang ([e-mail]), Xu Wang ([e-mail])Tel.: [phone]. Fax: [phone].<br><b>Data in Figure 1 (Continental-scale impact of bomb 14C).xlsx</b>：The file contains three worksheets corresponding to the data presented in Figure 1, each addressing the radiocarbon (Δ14C) impact of historical nuclear bomb tests. Sheet “Figure 1a” presents Δ14C differences (ΔΔ14C) between background stations in China and compilations from corresponding latitudinal zones. Compilation data for NH-3, NH-2, and NH-1 are from Hua et al.1 The background stations in China include: Nanling (3000 km from Lop Nor, this study), Huangzhong (1300 km from Lop Nor, Xiong et al.), 2 Shangdianzi (2400 km from Lop Nor, Niu et al.), 3 Mingyin (2000 km from Lop Nor, Dai and Fan), 4 and Dailing (3200 km from Lop Nor, Dai and Fan). 5 All these stations use tree-ring samples, with comparisons conducted during the tree-ring growth periods: March–October at Nanling and Minying, May–August at Huangzhong, and May–September at Shangdianzi and Dailing. It also includes the yield of fission and fusion bomb tests at Semipalatinsk and Lop Nor.6 Sheet “Figure 1b” shows ΔΔ14C between background stations in China and European backgrounds (Vermunt and Jungfraujoch (JFJ), atmospheric data). The Vermunt data (1959–1983) is from Levin et al., and the JFJ data (1986–2015) is from Hammer and Levin. 7, 8 It also includes the yield of fission and fusion bomb tests at Semipalatinsk and Lop Nor.6. Sheet “Figure 1b” displays ΔΔ14C between European sites, zonal compilations and European backgrounds. These European sites including: Fruholmen (air, 1100 km from Novaya, Nydal and Lövseth), 9 Trondheim (air, 2100 km from Novaya, Nydal and Lövseth), 9 Trondelag (tree-ring, 2100 km from Novaya, Svarva et al.),10 Lindesnes (air, 2650 km from Novaya, Nydal and Lövseth), 9 Eastwen Jutland (tree-ring, 2700 km from Novaya, Kudsk et al.)11 and Niepolomice (tree-ring, 3100 km from Novaya, Rakowski et al.).12 Vermunt and JFJ are 3100 km from Novaya. It also includes the yield of fission and fusion bomb tests at Novaya.6<b>Data in Figure 2 (trajectory_frequency) folder: </b>The subfolder “Figure 2a–c – Lop Nor – HZ, SDZ, NL” contains trajectory frequency files for Huangzhong (HZ), Shangdianzi (SDZ), and Naling (NL) from 27 October to 26 November 1966, following the Lop Nor bomb test on 27 October 1966. The subfolder “Figure 2d–e – Semipalatinsk – HZ, NL” includes trajectory frequency files for Huangzhong and Naling from 22 August to 19 November 1957, during the Semipalatinsk bomb tests conducted between 22 August and 26 September 1957. The subfolder “Figure 2f – Novaya Zemlya – Fruholmen” contains trajectory frequency files for Fruholmen from 5 August 1962 to 1 January 1963, corresponding to the Novaya Zemlya tests carried out from 5 August to 25 December 1962.<b>Data in Figure 3 and SI Figure2 (Comparison of CO2ff estimations)</b><b>.xlsx:</b><b> </b>It comprises four worksheets presenting CO_2ff estimations for Xi’an, Beijing, Shenzhen, and Hengshan, respectively. . Each worksheet includes results derived using regional (Huangzhong (HZ), Shangdianzi (SDZ), Nanling (NL)), latitudinal (NH-1, NH-2, NH-3), and European (EU) background references. This data is both source data for Figure 3 and SI Figure2.<b>Data in SI Figure 1 (Δ14C curves).xlsx: </b>It contains Δ14C curves of Nanling compared to global stations. Tree-ring Δ14C datasets include Nanling (1921-2020, this study), Huangzhong (1957-2015)2 and Shangdianzi (1948-2018)3 in China, as well as of Olympic Peninsula, US (1921-1953) 13. Δ14C compilation of NH-3 is from Hua et al.1 Atmospheric Δ14C levels of European backgrounds, includes Vermunt (1959-1983) and Jungfraujoch (1986-2019) 7, 8.<b>Data in SI Figure 3 (Temperature and precipitation of Nanling).xlsx: </b>This file provides monthly temperature and precipitation records from a site near the Nanling tree ring sampling station.<b>Data in SI Table 1 (ecological half-life of bomb 14C).xlsx: </b>This file contains the ecological half-life (T1/2,e) of bomb 14C. The datasets in low-mid latitudinal zone include Nanling (this study), Mingyin,4 and compilations of NH-3 during March–October (Same with the growth period of Nanling trees).1 The datasets in middle latitudinal zone include Huangzhong, 2 and compilations of NH-2 during May–Augst (Same with the growth period of Huangzhong trees).1 The datasets in mid-high latitudinal zone include Shangdianzi,3 European backgrounds (Vermunt and JFJ)7, 8, and compilations of NH-1 during May–September (Same with the growth period of Huangzhong trees).1<b>Data in SI Table 2 (CO2ff differences).xlsx:</b> This file shows d<b>ifferences</b><b> in </b><b>CO</b>_{<strong>2ff</strong>}<b> estimation using various backgrounds. </b>The table includes: 1) the differences between regional backgrounds (Huangzhong, Shangdianzi, Nanling) and latitudinal backgrounds (NH-1, NH-2, NH-3); 2) the differences between regional backgrounds and European backgrounds (Vermunt and JFJ). The evaluated sites include Shenzhen and Hengshan, located within the NH-3 region; Xi’an, located within the NH-2 region; and Beijing, located within the NH-1 region.<b>Source 14C data.xlsx:</b> This file contains the ¹⁴C measurements generated in this study, presented across three worksheets corresponding to the Nanling background station, the Shenzhen urban station, and the Hengshan regional station.<b>Source CO2 data (Mauna Loa).xlsx:</b> CO2 data from Mauna Loa (MLO) which belong to Global Greenhouse Gas Reference Network were used in this study as the background CO2 levels, which available from 1970 to 2020 (https://gml.noaa.gov/ccgg/trends/).14<b>Statistical analysis code and data folder: </b>It contains the python code, source data and results that conducted the statistical analysis.<b>References:</b>1. Hua, Q. et al. Atmospheric Radiocarbon for the Period 1950-2019. <i>Radiocarbon</i> <b>64</b>, 723-745 (2022).2. Xiong, X.H. et al. Time series of atmospheric Δ¹⁴CO₂ recorded in tree rings from Northwest China (1957-2015). <i>Chemosphere</i> <b>272</b> (2021).3. Niu, Z., Feng, X., Zhou, W., Wang, P. &amp; Cai, Q. Tree-ring Δ¹⁴C time series from 1948 to 2018 at a regional background site, China: Influences of atmospheric nuclear weapons tests and fossil fuel emissions. <i>Atmos. Environ.</i> <b>246</b>, 118156 (2021).4. Dai, K. &amp; Fan, C.Y. Bomb produced 14C content in tree rings grown at different latitudes. <i>Radiocarbon</i> <b>28</b>, 346-349 (1986).5. Dai, K., Qian, Y. &amp; Fan, C.Y. Bomb-produced ¹⁴C in tree rings. <i>Radiocarbon</i> <b>34</b>, 753-756 (1992).6. UNSCEAR United Nations Scientific Committee on the Effects of Atomic Radiation, UNSCEAR 2000 Report to the general assembly, with scientific annexes volume I: Sources and effects ofionizing radiation. (2000).7. Levin, I. et al. Delta ¹⁴CO₂ records from two sites in Central Europe. <i>CDIAC</i> (1997).8. Hammer, S. &amp; Levin, I. Monthly Mean Atmospheric Δ¹⁴CO₂ at Jungfraujoch and Schauinsland From 1986 to 2016. <i>heiDATA</i> <b>V2</b> (2017).9. Nydal, R. &amp; Lövseth, K. Carbon-14 measurements in atmospheric CO₂ from northern and southern hemisphere sites, 1962-1993. <i>Carbon Dioxide Information Analysis Center, World Data Center-A for Atmospheric Trace Gases, Oak Ridge National Laboratory, Tennessee.</i> (1996).10. Svarva, H. et al. The 1953–1965 rise in atmospheric bomb ¹⁴C in central Norway. <i>Radiocarbon</i> <b>61</b>, 1765-1774 (2019).11. Kudsk, S.G.K. et al. What is the carbon origin of early-wood? <i>Radiocarbon</i> <b>60</b>, 1457-1464 (2018).12. Rakowski, A.Z. et al. Radiocarbon method in environmental monitoring of CO₂ emission. <i>Nucl. Instrum. Meth. B.</i> <b>294</b>, 503-507 (2013).13. Stuiver, M. &amp; Quay, P.D. Atmospheric ¹⁴C Changes Resulting from Fossil-Fuel Co2 Release and Cosmic-Ray Flux Variability. <i>Earth. Planet. Sc. Lett.</i> <b>53</b>, 349-362 (1981).14. Thoning, K., Crotwell, A. &amp; Mund, J. Atmospheric Carbon Dioxide Dry Air Mole Fractions from continuous measurements at Mauna Loa, Hawaii, Barrow, Alaska, American Samoa and South Pole. 1973–2020. <i>Global Monitoring Laboratory (GML): Boulder, CO, USA</i> (2021).