Fallout traces of the Fukushima NPP accident in southern West Siberia (Novosibirsk, Russia)

Mercury geochemistry of marine sediments from the eastern Laptev Sea: The spatial distribution, levels, and contamination assessment

Twenty-seven sediment samples from the eastern Laptev Sea were analyzed for mercury and total organic carbon as well as grain-size distribution. The average total mercury (THg) concentrations in sediments are 29 ± 14 μg kg^-1. A significant correlation of THg content with total organic carbon and clay and silt fractions was shown. The ²¹⁰Pb-dated sediment core was used to evaluate the contamination degree and flux of THg in sediments from the eastern Laptev Sea. The average sedimentation rate for the all dated intervals was 0.17 cm/year. The THg flux increased from 20 to 28 μg/m²/year in the period of 1892-1950 to 53-59 μg/m²/year in the modern period of 2011-2015. According to various indices, the ecological risk from THg in studied sediment was low.

137Cs and 40K activity concentrations in edible wild mushrooms from China regions during the 2014–2016 period

Introduction. Contamination by radiocaesium of edible wild mushrooms after major nuclear accidents is a long-lasting process in some regions of the world. Following greater awareness of radioactive pollution in Asia, particularly after the Fukushima accident, this study investigated the radioactivity of 137Cs and 40K contamination in edible wild mushrooms in China. Study objects and methods. The objects of the research were edible wild mushrooms collected during 2014 to 2016, from the Inner Mongolian and Yunnan regions of China. To obtain an insight into any environmental impacts to distant regions of mainland Asia, the mushrooms were analyzed for 137Cs activity. In parallel, the natural activity of 40K was also determined and used to estimate the content of total K. The topsoil underneath the mushrooms was also investigated from a few sites in Bayanhushu in Inner Mongolia in 2015. Results and discussion. The results showed that in 4 to 6 mushrooming seasons after the accident, mushrooms from both regions were only slightly contaminated with 137Cs, which implied negligible consequences. The activity concentrations of 137Cs in dried caps and whole mushrooms in 63 of 70 lots from 26 locations were well below 20 Bq kg–1 dry weight. Two species (Lactarius hygrophoroides L. and Lactarius volemus L.), from Jiulongchi in Yuxi prefecture showed higher 137Cs activities, from 130 ± 5 to 210 ± 13 Bq kg–1 dw in the caps. 40K activities of mushrooms were around two- to three-fold higher. A composite sample of topsoil (0–10 cm layer) from the Bayanhushu site (altitude 920 m a.s.l.) in Inner Mongolia showed 137Cs activity concentration at a low level of 6.8 ± 0.7 Bq kg–1 dw, but it was relatively rich in potassium (40K of 595 ± 41 Bq kg–1 and total K of 17000 ± 1000 mg kg–1 dw). Conclusion. Wild mushrooms from the Yunnan and Inner Mongolia lands only slightly affected with radioactivity from artificial 137Cs. Lack of 134Cs showed negligible impact from Fukushima fallout. Ionizing radiation dose from 137Cs in potential meals was a fraction of 40K radioactivity. The associated dietary exposure to ionizing irradiation from 137Cs and 40K contained in mushrooms from the regions studied was considered negligible and low, respectively. Mushroom species examined in this study are a potentially good source of dietary potassium.

Assessment of mercury levels in modern sediments of the East Siberian Sea

Mercury (Hg) is an important environmental indicator of anthropogenic pollution. In this study, the Hg content in the bottom sediments of the East Siberian Sea was observed to range from 13 to 92 ppb, with an average of 36 ppb. Facies dependence was also observed and expressed as an increase in the Hg concentration in fine-sized sediments on the shelf edge and continental slope, compared to that in the sandy silts and sands of the inner shelf. The Hg accumulation in bottom sediments of the eastern part has increased over the past 150 years due to an increase in global emissions of anthropogenic Hg, which is caused by the transboundary transport of Hg to the Arctic. Moreover, changes in the Hg value, which occur due to the plankton arriving at the bottom sediments because of changes in hydrology and primary production, are thought to be associated with global warming.

Radioactive contamination of pine (Pinus sylvestris) in Krasnoyarsk (Russia) following fallout from the Fukushima accident

Following the Fukushima accident in March 2011, samples of pine trees (Pinus sylvestris) were collected from three sites near the city of Krasnoyarsk (Siberia, Russia) during 2011-2012 and analyzed for artificial radionuclides. Concentrations of Fukushima-derived radionuclides in the samples of pine needles in April 2011 reached 5.51 ± 0.52 Bq kg(-1)(131)I, 0.92 ± 0.04 Bq kg(-1)(134)Cs, and 1.51 ± 0.07 Bq kg(-1)(137)Cs. An important finding was the detection of (134)Cs from the Fukushima accident not only in the pine needles and branches but also in the new shoots in 2012, which suggested a transfer of Fukushima cesium isotopes from branches to shoots. In 2011 and 2012, the (137)Cs/(134)Cs ratio for pine needles and branches collected in sampling areas Krasnoyarsk-1 and Krasnoyarsk-2 was greater than 1 (varying within a range of 1.2-2.6), suggesting the presence of "older", pre-Fukushima accident (137)Cs. Calculations showed that for pine samples growing in areas of the Krasnoyarskii Krai unaffected by contamination from the nuclear facility, the activity of the Fukushima-derived cesium isotopes was two-three times higher than the activity of the pre-accident (137)Cs.

Comparison of the Chernobyl and Fukushima nuclear accidents: a review of the environmental impacts

The environmental impacts of the nuclear accidents of Chernobyl and Fukushima are compared. In almost every respect, the consequences of the Chernobyl accident clearly exceeded those of the Fukushima accident. In both accidents, most of the radioactivity released was due to volatile radionuclides (noble gases, iodine, cesium, tellurium). However, the amount of refractory elements (including actinides) emitted in the course of the Chernobyl accident was approximately four orders of magnitude higher than during the Fukushima accident. For Chernobyl, a total release of 5,300 PBq (excluding noble gases) has been established as the most cited source term. For Fukushima, we estimated a total source term of 520 (340-800) PBq. In the course of the Fukushima accident, the majority of the radionuclides (more than 80%) was transported offshore and deposited in the Pacific Ocean. Monitoring campaigns after both accidents reveal that the environmental impact of the Chernobyl accident was much greater than of the Fukushima accident. Both the highly contaminated areas and the evacuated areas are smaller around Fukushima and the projected health effects in Japan are significantly lower than after the Chernobyl accident. This is mainly due to the fact that food safety campaigns and evacuations worked quickly and efficiently after the Fukushima accident. In contrast to Chernobyl, no fatalities due to acute radiation effects occurred in Fukushima.

An overview of Fukushima radionuclides measured in the northern hemisphere

The Great East Japan Earthquake and tsunami on March 11, 2011 resulted in the tragic accident at the Fukushima Nuclear Power Plant (NPP) and subsequently uncontrolled release of radioactive contaminants into the atmosphere. This review article attempts to compile and interpret data collected by various national and international monitoring networks in response to the Fukushima releases across the northern hemisphere. The majority of the releases occurred during the period March 12-22 with a maximum release phase from March 14-17, 2011. The radioactivity released was dominated by volatile fission products including isotopes of the noble gases (xenon and krypton), iodine, cesium, and tellurium. The radioactive gases and particles released in the accident were dispersed over the middle latitudes of the entire northern hemisphere and for the first time also measured in the southern Hemisphere. Isotopes of iodine and cesium were detected in air, water, milk and food samples collected across the entire northern hemisphere. Elevated levels of fission products were detected from March to May 2011 at many locations over the northern hemisphere. This article focuses on the most prevalent cesium and iodine isotopes, but other secondary isotopes are also discussed. Spatial and temporal patterns and differences are contrasted. The activity ratios of (131)I/(137)Cs and (134)Cs/(137)Cs measured at several locations are evaluated to gain an insight into the fuel burn-up, the inventory of radionuclides in the reactor and the isotopic signature of the accident. It is important to note that all of the radiation levels detected outside of Japan have been very low and are well below any level of public and environmental hazard.

Artificial radioactivity in environmental media (air, rainwater, soil, vegetation) in Austria after the Fukushima nuclear accident

Several environmental media in Austria were monitored for artificial radionuclides released during the Fukushima nuclear accident. Air (up to 1.2 mBq/m(3) particulate (131)I) and rainwater (up to 5.2 Bq/L (131)I) proved to be the media best suited for the environmental monitoring, allowing also a temporal resolution of the activity levels. Significant regional differences in the wet deposition of (131)I with rain could be observed within the city of Vienna during the arrival of the contaminated air masses. Forward-trajectory analysis supported the hypothesis that the contaminated air masses coming from the northwest changed direction to northeast over Northern Austria, leading to a strong activity concentration gradient over Vienna. In the course of the environmental monitoring of the Fukushima releases, this phenomenon-significant differences of (131)I activity concentrations in rainwater on a narrow local scale (8.1 km)-appears to be unique. Vegetation (grass) was contaminated with (131)I and/or (137)Cs at a low level. Soil (up to 22 Bq/kg (137)Cs) was only affected by previous releases (nuclear weapon tests, Chernobyl). Here, also significant local differences can be observed due to different deposition rates during the Chernobyl accident. The effective ecological half-lives of (137)Cs in soil were calculated for four locations in Austria. They range from 7 to 30 years. No Austrian sample investigated herein exceeded the detection limit for (134)Cs; hence, the Fukushima nuclear accident did not contribute significantly to the total radiocesium inventory in Austrian environmental media. The levels of detected radioactivity were of no concern for public health.