Effects of the Storm Daniel on the environmental radiological map of Thessaly

Abstract Thessaly includes one of Greece’s largest plains and the watershed of Pindus Mountain range and thus is particularly susceptible to flooding. Storm Daniel caused extensive floodings in Thessaly basins, in September 2023. Significant agricultural productivity, along with relevant industrial activity, takes place in Thessaly; therefore, such intensive climate change phenomena affect not only the topical ecosystem but the national economy. In this work, Thessaly was divided into six sectors, to investigate the changes in the environmental radioactivity map caused by the Storm Daniel. Samples were collected from flooded and not-flooded locations in each sector. γ-Spectroscopy was performed on the samples with a high-purity germanium detector. The results for all the sectors show Cs-137 concentrations in the flooded areas lower than the ones in the not-flooded areas. Specifically, the mean concentration of Cs-137 in flooded and not-flooded areas is 4.6 Bq/kg and 38.8 Bq/kg, respectively. The concentrations of the other radionuclides vary across the sampled sectors, indicating the influence of flood events on the distribution of the NORM radionuclides in the soil. Remarkable differences are observed only in flooded and not-flooded areas for U-238 and Ra-226. The mean concentrations of U-238 are 18.6 Bq/kg and 24.7 Bq/kg, and the mean concentrations of Ra-226 are 21.1 Bq/kg and 28.5 Bq/kg, respectively. The uncertainty of the measurements is approximately 17% for U-238 and about 6% for all the other radionuclides. The findings contribute to the understanding of the environmental impact of floods, particularly in regions with significant agricultural and ecological value. This work suggests that floods can alter the radionuclide profile of soils. Additionally, it highlights the need for ongoing monitoring and further research to assess the long-term effects of flooding on radiological maps and the broader implications for the environment and public health.