Effects of Large-Scale Wildfires on the Redistribution of Radionuclides in the Chornobyl River System.

Wildfires in radiologically contaminated areas raise significant concerns due to potential radionuclides redistribution and increased public radiation exposure. This study examined the impact of the 2020 Chornobyl wildfire on the redistribution of radionuclides, specifically Cs and Sr, in the Chornobyl River system. We determined the quantities and speciation of Cs and Sr in charred residues and soil after wildfires and analyzed the riverine concentrations of these radionuclides based on long-term monitoring data.

Hydrological setting controls Cs and Sr concentrations in a headwater catchment in the Chornobyl Exclusion Zone.

Concentration-discharge relationships are widely used to understand the hydrological processes controlling river water chemistry. This study investigates how hydrological processes affect radionuclide (Cs and Sr) concentrations in surface water in headwater catchments within the Chornobyl Exclusion Zone (ChEZ) in Ukraine. In the flat wetland catchments, the depth of the saturated soil layer changes little throughout the year, but changes in the saturated soil surface area during snowmelt and immediately after rainfall affect water chemistry by changing the opportunities for contact between the surface water and the soil surface.

Evaluating changes in radionuclide concentrations and groundwater levels before and after the cooling pond drawdown in the Chornobyl Nuclear Power Plant vicinity.

In the vicinity of the Chornobyl Nuclear Power Plant (ChNPP), the cooling pond (CP) was an artificially maintained reservoir with water levels regulated to 7 m above the Pripyat River until May 2014, when its pumps stopped operating, resulting in a natural drawdown. To investigate the surface-groundwater system before and after the drawdown, we evaluated the spatial and temporal changes in Sr and Cs radionuclide concentrations and groundwater levels in the shallow unconfined aquifer near the ChNPP from 2010 to 2019. Additionally, we compared water levels and Sr concentrations in Azbuchin Lake, wetlands inside the CP, and the Pripyat River.

Radiation-mediated supply of genetic variation outweighs the effects of selection and drift in Chernobyl Daphnia populations.

Populations experiencing varying levels of ionizing radiation provide an excellent opportunity to study the fundamental drivers of evolution. Radiation can cause mutations and thus supply genetic variation; it can also selectively remove individuals that are unable to cope with the physiological stresses associated with radiation exposure, or non-selectively cull swathes of the population, reducing genetic variation. Since the nuclear power plant explosion in 1986, the Chernobyl area has experienced a spatially heterogeneous exposure to varying levels of ionizing radiation.

Europe-Wide Atmospheric Radionuclide Dispersion by Unprecedented Wildfires in the Chernobyl Exclusion Zone, April 2020.

From early April 2020, wildfires raged in the highly contaminated areas around the Chernobyl nuclear power plant (CNPP), Ukraine. For about 4 weeks, the fires spread around and into the Chernobyl exclusion zone (CEZ) and came within a few kilometers of both the CNPP and radioactive waste storage facilities. Wildfires occurred on several occasions throughout the month of April.

Responses of DNA Mismatch Repair Proteins to a Stable G-Quadruplex Embedded into a DNA Duplex Structure.

DNA mismatch repair (MMR) plays a crucial role in the maintenance of genomic stability. The main MMR protein, MutS, was recently shown to recognize the G-quadruplex (G4) DNA structures, which, along with regulatory functions, have a negative impact on genome integrity. Here, we studied the effect of G4 on the DNA-binding activity of MutS from (methyl-independent MMR) in comparison with MutS from (methyl-directed MMR) and evaluated the influence of a G4 on the functioning of other proteins involved in the initial steps of MMR.

NMR resonance assignment and backbone dynamics of a C-terminal domain homolog of orange carotenoid protein.

Photoprotection in cyanobacteria is mediated by the Orange Carotenoid Protein (OCP), a two-domain photoswitch which has multiple natural homologs of its N- and C-terminal domains. Recently, it was demonstrated that C-terminal domain homologs (CTDHs) of OCP are standalone carotenoproteins participating in multidirectional carotenoid transfer between membranes and proteins. Non-covalent embedment of a ketocarotenoid causes dimerization of the small 16-kDa water-soluble CTDH protein; however, dynamic interactions of CTDH with membranes and other proteins apparently require the monomeric state.

Simulating dissolved Sr concentrations within a small catchment in the Chernobyl Exclusion Zone using a parametric hydrochemical model.

Strontium-90 (Sr) is the major long-lived radionuclide derived from the Chernobyl accident, and is still being detected in the heavily contaminated catchments of the Chernobyl Exclusion Zone. This study examines the long-term decrease in the dissolved-phase Sr concentration and the concentration-discharge (Sr-Q) relationship in stream water since the accident. We show that the slow decline in Sr follows a double-exponential function, and that there is a clear relationship between Sr and Q.

Impact of wildfire on Cs and Sr wash-off in heavily contaminated forests in the Chernobyl exclusion zone.

Wildfires may play a role in redistributing radionuclides in the environment in combination with hydrological processes such as surface runoff and soil erosion. We investigated plot-scale radionuclide wash-off at forest sites affected by wildfires in the Chernobyl Exclusion Zone (CEZ). We also compared speciation of the washed-off radionuclides with those in previous studies conducted just after the accident in 1986.

Variation in chronic radiation exposure does not drive life history divergence among populations across the Chernobyl Exclusion Zone.

Ionizing radiation is a mutagen with known negative impacts on individual fitness. However, much less is known about how these individual fitness effects translate into population-level variation in natural environments that have experienced varying levels of radiation exposure. In this study, we sampled genotypes of the freshwater crustacean, , from the eight inhabited lakes across the Chernobyl Exclusion Zone (CEZ).

Impact of Environmental Radiation on the Health and Reproductive Status of Fish from Chernobyl.

Aquatic organisms at Chernobyl have now been chronically exposed to environmental radiation for three decades. The biological effects of acute exposure to radiation are relatively well documented, but much less is known about the long-term effects of chronic exposure of organisms in their natural environment. Highly exposed fish in freshwater systems at Chernobyl showed morphological changes in their reproductive system in the years after the accident.

Worldwide isotope ratios of the Fukushima release and early-phase external dose reconstruction.

Measurements of radionuclides (RNs) in air made worldwide following the Fukushima accident are quantitatively compared with air and soil measurements made in Japan. Isotopic ratios RN:(137)Cs of (131)I, (132)Te, (134,136)Cs, are correlated with distance from release. It is shown, for the first time, that both within Japan and globally, ratios RN:(137)Cs in air were relatively constant for primarily particle associated radionuclides ((134,136)Cs; (132)Te) but that (131)I shows much lower local (<80 km) isotope ratios in soils relative to (137)Cs.

Testing models for predicting the behaviour of radionuclides in aquatic systems.

The paper describes the main results of the international EMRAS model testing exercise for radionuclide transport in watershed-river and estuarine systems. The exercises included the following scenarios: multi-point source of (3)H discharge into the Loire River (France), radioactive contamination of the Dnieper-Southern Boug estuary (Ukraine), remobilisation of radionuclide contamination from the Pripyat River floodplain (Ukraine) following the Chernobyl accident, release of radionuclides into the Techa River (Russia) and behaviour of (226)Ra in the Huelva estuary (Spain).

Assessment of state-of-the-art models for predicting the remobilisation of radionuclides following the flooding of heavily contaminated areas: the case of Pripyat River floodplain.

The performances of models are assessed to predict the wash-off of radionuclides from contaminated flooded areas. This process should be accounted for in the proper management of the aftermath of a nuclear accident. The contamination of the Pripyat River water following the inundation of a floodplain heavily contaminated by (90)Sr and (137)Cs of Chernobyl origin is used as the basis for modelling.