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Abstract

This study presents long-term findings (1987-2008) on the vertical migration of 137Cs from the Chornobyl accident in undisturbed grassland soils in central and northern Sweden. We examined five mineral and three organic soils, with 137Cs deposition in 1986 ranging from 16 to 190 kBq m2. 137Cs activities were measured in 1 cm slices at depths of 0-10 cm and in 2.5 cm slices at 10-50 cm. Distribution (kBq m2) was calculated for different soil horizons, and migration rates were determined based on observed depths. During the initial period after the fallout (1987-1992), 137Cs was primarily located in the upper 0-2 cm layers of both mineral and organic soils, comprising 77 % to 94 % of the radionuclide. During the intermediate period (1994-2003), the average migration depth was 4.0 cm in mineral soils and 5.5 cm in the organic soils while during the later period (2004-2008) it was 4.4 and 7.0 cm, respectively. After about 20 years, approximately 80 % of the 137Cs activity was found in the upper 0-6 cm at five out of eight sites, and 75-78 % within 0-9 cm at two sites regardless of soil type. The average radionuclide migration rate of 137Cs in the period 1987 to 2008 across various sites was 0.31 cm yr-1. In mineral soils, the average migration rate was 0.28 cm yr-1 (range 0.13-0.47) and in organic soils it was 0.3 cm yr-1 (range 0.17-0.76). There was no significant relationship between soil clay content in mineral soils and the average migration depth of the radionuclide during the study period (P = 0.423).

Keywords

Chornobyl fallout; Field study; Grassland; Migration rate; Radiocaesium; Soil type

Published in

Geoderma
2025, volume: 461, article number: 117479
Publisher: ELSEVIER

SLU Authors

UKÄ Subject classification

Environmental Sciences
Soil Science

Publication identifier

  • DOI: https://doi.org/10.1016/j.geoderma.2025.117479

Permanent link to this page (URI)

https://res.slu.se/id/publ/143437