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The concentration and sorption behavior of 237 Np on the bottom sediments of water bodies in the Far East region of Russia (Lake Khanka and Peter the Great Bay) were studied for the first time. The 237 Np concentrations vary from 1.06 × 10 -6 to 4.43 × 10 -5 mBq g -1 in the bottom sediments of Lake Khanka and from 1.05 × 10 -4 to 2.52 × 10 -3 mBq g -1 for Amur Bay. The experiment on the adsorption of Np on marine and lake sediment showed that it is sorbed through complexation with silicates (albite, leucite). The Np sorption isotherm on marine sediments is described by the Langmuir equation; the distribution coefficients (Kd) of Np vary from 57 to 588 mL g -1 . For lake sediments, the isotherm is described by the Henry equation; the Kd value reaches 935 mL g -1 ., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Kuzmenkova Natalia reports financial support was provided by Russian Science Foundation. Hou Xiaolin reports financial support was provided by National Natural Science Foundation of China. Co-author is an assocaited editor in Journal of Environmental radioactivity., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

About ten years have passed since the last published report in Russian on the speciation and distribution features of radionuclides in the bottom sediment of Production Association (PA) "Mayak" (further mentioned as Mayak) artificial reservoirs. Herein, the desorption parameters of 137 Cs, 90 Sr, 241 Am, and 238,239+240 Pu and their association with bottom sediment components were investigated in two Mayak reservoirs (R-17 (decommissioned) and R-4 (still in use) with big differences in size, activity and water regime). It was established that 137 Cs and 90 Sr desorption from the R-17 bottom sediment reach constant values after 24 h, and the desorption degree is not dependant on pH but on ionic strength. Sequential extraction indicated that the main accumulation mechanism of 137 Cs is incorporation into the clay minerals. The maximum plutonium content was detected in the residual fraction of the R-17 bottom sediment, which could be associated with the effects of precipitation aging. In R-4, plutonium is equally distributed between residual and bound to organic matter fractions. The 241 Am is associated with carbonates in the R-17 bottom sediment and with organic matter in the R-4 bottom sediment and to lesser extent with iron-manganese oxides. The radionuclides are becoming less environmentally available with time since deposition., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

In April and August 2015, a massive fire occurred in the Chernobyl Exclusion zone. The fire spread to neighboring areas due to the prevailing strong winds. In this paper, we analyze the peat fires as a unique source of radioactive contamination. After an expedition directly to the peat fire site (the evacuation zone of the Bryansk region), we collected a number of aerosol samples. We came to the conclusion that peat fires cannot be the reason for radioactive particle transport in the Bryansk region as well as in the Chernobyl evacuation zone. During the peat fire, radioactive contamination was not transferred by aerosols beyond 500 m. The 137 Cs concentration in the aerosol filters varied between 0.55 and 0.64 Bq/m 3 , and that at the same distance from the fire seat and peat edge was 4.4∙10 -3 Bq/m 3 ; the activity values in the peat bog and in the nearest inhabited locality did not exceed the background values. Strontium-90 was not found in aerosol samples. The soil-to-air transport rate of 137 Cs was 2.7∙10 -6 . After the Chernobyl accident, the majority of the 137 Cs was incorporated into the structure of clay minerals, and these did not change during the peat fire. The mobility of 137 Cs in the flight peat material particles was established. To confirm the territory status of the evacuation zone, we also collected some food samples. Berries and mushrooms consumed at the assumed rate for dose estimation would result in doses that exceed the public dose limit by approximately a factor of five., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)