Measurement of 129I and 137Cs in soils from belarus and reconstruction of 131I deposition from the chernobyl accident

129 I and 137 Cs have been measured in a large number of soil samples collected throughout the country of Belarus to support efforts for thyroid-dose reconstruction following the Chernobyl accident. Samples of soil consisting of multiple 30-cm-deep cores per site were sampled following a selection process to ensure sites were undisturbed and representative. Samples were measured by accelerator mass spectrometry (AMS) for 129 I, gamma spectrometry for 137 Cs, and gas chromatography (GC) for total iodine. Results show that both 129 I and 137 Cs are retained firmly in the top ∼15 to 20 cm of the soil. Our results also suggest that the correlation between 129 I and 137 Cs deposition across the country of Belarus is poor; hence, 129 I is a better surrogate for 131 I than is 137 Cs. It was also noted that total iodine concentrations in topsoil from Belarus are low compared with other regions of the world where radiogenic thyroid cancer has been studied.