DOI: 10.5061/dryad.3bk3j9kgb
title: Uncovering transport, deposition and impact of radionuclides released after the early spring 2020 wildfires in the Chernobyl Exclusion Zone

description: In the beginning of April 2020, large fires that started in the Chernobyl
 Exclusion Zone (CEZ) established after the Chernobyl accident in 1986
 caused media and public concerns about the health impact from the
 resuspended radioactivity. In this paper, the emissions of previously
 deposited radionuclides from these fires are assessed and their dispersion
 and impact on the population is examined relying on the most recent data
 on radioactive contamination and emission factors combined with satellite
 observations. About 341 GBq of 137Cs, 51 GBq of 90Sr, 2
 GBq of 238Pu, 33 MBq of 239Pu, 66 MBq of 240Pu
 and 504 MBq of 241Am were released in 1st–22nd April
 2020 or about 1,000,000,000 times lower than the original accident in 1986
 and mostly distributed in Central and East Europe. The large size of
 biomass burning particles carrying radionuclides prevents long-range
 transport as confirmed by low concentrations reported in Europe.
 The highest cumulative effective doses (&gt;15 μSv)
 were calculated for firefighters and the population living in the CEZ,
 while doses were much lower in Kiev (2–5 μSv) and negligible in
 Europe. All doses are radiologically insignificant and no health impact on
 the European population is expected from the April 2020 fires.
description: Emissions were calculated with three methods.
 Method 1 (bottom-up) uses burned area, based on a modified method
 from [<i>Stohl et al.</i>, 2007], and MODIS active fires with
 the maximum confidence level (100%) combined with a statistical
 approach [<i>Wotawa et al.</i>, 2006]. Then, we use the most
 recently updated emission factors (EFs) for radionuclides [<i>Hao et
 al.</i>, 2018] together with ground contamination
 data [<i>Kashparov et al.</i>, 2001, 2003, 2018] from the CEZ
 (Fig. S 2, Fig. S 3). Method 2 (top-down) combines EFs
 of <sup>137</sup>Cs (in gr species per kg of dry mass burned)
 from [<i>Hao et al.</i>, 2018] with combusted biomass (in kg
 of dry mass) from Copernicus Atmosphere Monitoring Service (CAMS) Global
 Fire Assimilation System (GFAS) [<i>Kaiser et al.</i>,
 2012]. Method 3 (top-down) uses experimental ratios
 of <sup>137</sup>Cs with particulate organic matter (POM)
 from [<i>Strode et al.</i>, 2012] for boreal regions and
 calculates emissions using POC from CAMS GFAS [<i>Kaiser et
 al.</i>, 2012]. Emissions calculated from the
 three different methods were ingested to the Lagrangian particle transport
 model FLEXPART (Flexible Particle Dispersion Model) version 10.4
 [<i>Pisso et al.</i>, 2019] that simulated transport and
 deposition
 of <sup>137</sup>Cs, <sup>90</sup>Sr, <sup>238</sup>Pu, <sup>239</sup>Pu, <sup>240</sup>Pu and <sup>241</sup>Am. A preliminary assessment on the committed internal (inhalation) and external (air submersion/immersion and deposition) exposure has been conducted for four population groups (1-year old infants, 10-year old children, adults and workers/firefighters). The methodology is based on the[<i>WHO</i>, 2012] report for Fukushima and includes the most recent updates on dose calculations. 
description: <strong>Preprocessing.tar</strong> includes MODIS
 active fires from 1-22 April, contamination data
 for <sup>137</sup>Cs, <sup>90</sup>Sr, <sup>238</sup>Pu, <sup>239</sup>Pu, <sup>240</sup>Pu and <sup>241</sup>Am and CAMS GFAS POC and FRP that were used to calculate emissions with 3 methods. The Python scripts used to calculate emissions and create the RELEASES files for FLEXPART model are also included. <strong>FLEXPART_forward.tar</strong> includes all FLEXPART output netCDF files, in which the transport and deposition of <sup>137</sup>Cs, <sup>90</sup>Sr, <sup>238</sup>Pu, <sup>239</sup>Pu, <sup>240</sup>Pu and <sup>241</sup>Am were simulated. <strong>FLEXPART_backward.tar</strong> includes all FLEXPART output binary files that prove that the origin of air masses when measurements of radioactivity were carried out was directly from the Chernobyl Exclusion Zone. Three receptor points were investigated, namely Thessaliniki, Vienna International Centre (VIC) and Kiev. Each output is linked to a specific particle size distribution for the species as explained in the manuscript. <strong>Postprocessing.tar</strong> consists of all python scripts to create the figures and videos of the manuscript including those that were used for validation of the model and for the dosimetric assessment.