Nikolaos Evangeliou

Radioactive pollution in Athens, Greece due to the Fukushima nuclear accident

As a result of the nuclear accident in Fukushima Dai-ichi power plant, which started on March 11, 2011, radioactive pollutants were transferred by air masses to various regions of the Northern hemisphere, including Europe. Very low concentrations of (131)I, (137)Cs and (134)Cs in airborne particulate matter were measured in Athens, Greece during the period of March 24 to April 28, 2011. The maximum air concentration of (131)I was measured on April 6, 2011 and equaled 490 ± 35 μBq m(-3). The maximum values of the two cesium isotopes were measured on the same day and equaled 180 ± 40 μBq m(-3) for (137)Cs and 160 ± 30 μBq m(-3) for (134)Cs. The average activity ratio of (131)I/(137)Cs in air was 3.0 ± 0.5, while the corresponding ratio of (137)Cs/(134)Cs equaled 1.1 ± 0.3. No artificial radionuclides could be detected in air after April 28, 2011. Traces of (131)I as a result of radioactive deposition were measured in grass, soil, sheep milk and meat. The total deposition of (131)I (dry + wet) was 34 ± 4 Bq m(-2), and of (137)Cs was less than 10 Bq m(-2). The maximum concentration of (131)I in grass was 2.1 ± 0.4 Bg kg(-1), while (134)Cs was not detected. The maximum concentrations of (131)I and (137)Cs in sheep milk were 1.7 ± 0.16 Bq kg(-1) and 0.6 ± 0.12 Bq kg(-1) respectively. Concentrations of (131)I up to 1.3 ± 0.2 Bq kg(-1) were measured in sheep meat. Traces of (131)I were found in a number of soil samples. The radiological impact of the Fukushima nuclear accident in Athens region was practically negligible, especially as compared to that of the Chernobyl accident and also to that of natural radioactivity.

Global and local cancer risks after the Fukushima Nuclear Power Plant accident as seen from Chernobyl: A modeling study for radiocaesium (134Cs & 137Cs)

The accident at the Fukushima Daiichi Nuclear Power Plant (NPP) in Japan resulted in the release of a large number of fission products that were transported worldwide. We study the effects of two of the most dangerous radionuclides emitted, (137)Cs (half-life: 30.2years) and (134)Cs (half-life: 2.06years), which were transported across the world constituting the global fallout (together with iodine isotopes and noble gasses) after nuclear releases. The main purpose is to provide preliminary cancer risk estimates after the Fukushima NPP accident, in terms of excess lifetime incident and death risks, prior to epidemiology, and compare them with those occurred after the Chernobyl accident. Moreover, cancer risks are presented for the local population in the form of high-resolution risk maps for 3 population classes and for both sexes. The atmospheric transport model LMDZORINCA was used to simulate the global dispersion of radiocaesium after the accident. Air and ground activity concentrations have been incorporated with monitoring data as input to the LNT-model (Linear Non-Threshold) frequently used in risk assessments of all solid cancers. Cancer risks were estimated to be small for the global population in regions outside Japan. Women are more sensitive to radiation than men, although the largest risks were recorded for infants; the risk is not depended on the sex at the age-at-exposure. Radiation risks from Fukushima were more enhanced near the plant, while the evacuation measures were crucial for its reduction. According to our estimations, 730-1700 excess cancer incidents are expected of which around 65% may be fatal, which are very close to what has been already published (see references therein). Finally, we applied the same calculations using the DDREF (Dose and Dose Rate Effectiveness Factor), which is recommended by the ICRP, UNSCEAR and EPA as an alternative reduction factor instead of using a threshold value (which is still unknown). Excess lifetime cancer incidents were estimated to be between 360 and 850, whereas 220-520 of them will be fatal. Nevertheless, these numbers are expected to be even smaller, as the response of the Japanese official authorities to the accident was rapid. The projected cancer incidents are much lower than the casualties occurred from the earthquake itself (>20,000) and also smaller than the accident of Chernobyl.

Distribution of natural radioactivity in sediment cores from Amvrakikos Gulf (Western Greece) as a part of IAEA's campaign in the Adriatic and Ionian Seas

The vertical distribution of natural radionuclides ((232)Th decay, (238)U decay, (40)K and (210)Pb) was assessed in sediment cores collected from the Amvrakikos Gulf, (Ionian Sea, Western Greece). Two collection stations were selected, the first at the western part of the Gulf near Preveza Strait (13A station) and the other near the centre of the Gulf (13B station). Activity concentrations were measured by means of gamma-ray spectrometry using high-purity germanium (HPGe) detectors installed at two national laboratories. The activity concentration of (226)Ra was found in a range from 10 to 20 Bq kg(-1), while the activity concentration of (222)Rn daughters ((214)Pb, (214)Bi) ranged from 6 to 20 Bq kg(-1). The activity concentration of (228)Ac varied from 20 to 28 Bq kg(-1), while (220)Rn daughters ((212)Pb, (208)Tl) from 7 to 35 Bq kg(-1). As concerns (40)K and (210)Pb, their activities varied from 400 to 830 Bq kg(-1) and from 11 to 360 Bq kg(-1), respectively. Also, the data of (210)Pb were utilised in the calculations of the sedimentation rate along the sediment cores. Both locations were characterised by a consistent pattern with the average rates of 0.55 ± 0.02 and 0.32 ± 0.02 cm y(-1), corresponding to 13A and 13B stations, respectively. Finally, the measurements constituted the basis of the first reported database concerning the radiological condition of the Gulf and which can be reclaimed as reference values in future monitoring studies.

An overview of current knowledge concerning the health and environmental consequences of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident.

Since 2011, the scientific community has worked to identify the exact transport and deposition patterns of radionuclides released from the accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Japan. Nevertheless, there still remain many unknowns concerning the health and environmental impacts of these radionuclides. The present paper reviews the current understanding of the FDNPP accident with respect to interactions of the released radionuclides with the environment and impacts on human and non-human biota. Here, we scrutinize existing literature and combine and interpret observations and modeling assessments derived after Fukushima. Finally, we discuss the behavior and applications of radionuclides that might be used as tracers of environmental processes. This review focuses on (137)Cs and (131)I releases derived from Fukushima. Published estimates suggest total release amounts of 12-36.7PBq of (137)Cs and 150-160PBq of (131)I. Maximum estimated human mortality due to the Fukushima nuclear accident is 10,000 (due to all causes) and the maximum estimates for lifetime cancer mortality and morbidity are 1500 and 1800, respectively. Studies of plants and animals in the forests of Fukushima have recorded a range of physiological, developmental, morphological, and behavioral consequences of exposure to radioactivity. Some of the effects observed in the exposed populations include the following: hematological aberrations in Fukushima monkeys; genetic, developmental and morphological aberrations in a butterfly; declines in abundances of birds, butterflies and cicadas; aberrant growth forms in trees; and morphological abnormalities in aphids. These findings are discussed from the perspective of conservation biology.

Temporal and spatial distribution of 137Cs in Eastern Mediterranean Sea. Horizontal and vertical dispersion in two regions.

Caesium-137 activity concentration in the water columns of the Gulf of Patras (Central Greece) and the North-Eastern Aegean Sea (easterward to Lemnos Island) was investigated in selected sampling stations during the period September 2004-June 2006. The methodology followed was based on the sorption of caesium (Cs) on cotton wound cartridge filters impregnated by Cu(2)[Fe(CN)(6)] via in-situ pumping. In terms of the horizontal and vertical records, the activity concentrations of (137)Cs in the Gulf of Patras ranged between 1.2 and 6.7Bqm(-3), depending on the sampling period and the prevailing physicochemical regime at the sampling station. The general pattern of the decreased activity concentrations of (137)Cs with increasing depth was reversed in the Gulf of Patras during the cold period attributed to the prevailing advective processes of the area. The activity concentrations of (137)Cs in the North-Eastern Aegean Sea ranged from 2.6 to 12.8Bqm(-3), whereas significant stratified curves were observed during the warm period and also, in one station during the cold period. In terms of temporal variation, the discharges in the Gulf of Patras resulted in enhanced levels of (137)Cs, whereas in the North Aegean Sea the incoming water masses form the Black Sea had an apparent influence throughout the year by increasing the (137)Cs levels, hence presenting a weak seasonal variation. Comparing the two studied areas, one could say that the North Aegean Sea, as an open sea environment, presented higher concentrations due to the influence of the Black Sea water masses. The estimated inventories of (137)Cs in the Gulf of Patras ranged 0.25+/-0.03-0.79+/-0.03kBqm(-2), whereas in the North-Eastern Aegean Sea they ranged 0.33+/-0.02-0.92+/-0.03kBqm(-2).

Wildfires in Chernobyl-contaminated forests and risks to the population and the environment: A new nuclear disaster about to happen?

Radioactive contamination in Ukraine, Belarus and Russia after the Chernobyl accident left large rural and forest areas to their own fate. Forest succession in conjunction with lack of forest management started gradually transforming the landscape. During the last 28 years dead wood and litter have dramatically accumulated in these areas, whereas climate change has increased temperature and favored drought. The present situation in these forests suggests an increased risk of wildfires, especially after the pronounced forest fires of 2010, which remobilized Chernobyl-deposited radioactive materials transporting them thousand kilometers far. For the aforementioned reasons, we study the consequences of different forest fires on the redistribution of (137)Cs. Using the time frequency of the fires that occurred in the area during 2010, we study three scenarios assuming that 10%, 50% and 100% of the area are burnt. We aim to sensitize the scientific community and the European authorities for the foreseen risks from radioactivity redistribution over Europe. The global model LMDZORINCA that reads deposition density of radionuclides and burnt area from satellites was used, whereas risks for the human and animal population were calculated using the Linear No-Threshold (LNT) model and the computerized software ERICA Tool, respectively. Depending on the scenario, whereas between 20 and 240 humans may suffer from solid cancers, of which 10-170 may be fatal. ERICA predicts insignificant changes in animal populations from the fires, whereas the already extreme radioactivity background plays a major role in their living quality. The resulting releases of (137)Cs after hypothetical wildfires in Chernobyls forests are classified as high in the International Nuclear Events Scale (INES). The estimated cancer incidents and fatalities are expected to be comparable to those predicted for Fukushima. This is attributed to the fact that the distribution of radioactive fallout after the wildfires occurred to the intensely populated Western Europe, whereas after Fukushima it occurred towards the Pacific Ocean. The situation will be exacerbated near the forests not only due to the expected redistribution of refractory radionuclides (also trapped there), but also due to the nutritional habits of the local human and animal population.

How "lucky" we are that the Fukushima disaster occurred in early spring: predictions on the contamination levels from various fission products released from the accident and updates on the risk assessment for solid and thyroid cancers.

The present paper studies how a random event (earthquake) and the subsequent disaster in Japan affect transport and deposition of fallout and the resulting health consequences. Therefore, except for the original accident in March 2011, three additional scenarios are assessed assuming that the same releases took place in winter 2010, summer 2011 and autumn 2011 in order to cover a full range of annual seasonality. This is also the first study where a large number of fission products released from the accident are used to assess health risks with the maximum possible efficiency. Xenon-133 and (137)Cs are directly estimated within the model, whereas 15 other radionuclides are calculated indirectly using reported isotopic ratios. As much as 85% of the released (137)Cs would be deposited in continental regions worldwide if the accident occurred in winter 2010, 22% in spring 2011 (when it actually happened), 55% in summer 2011 and 48% if it occurred during autumn 2011. Solid cancer incidents and mortalities from Fukushima are estimated to be between 160 and 880 and from 110 to 640 close to previous estimations. By adding thyroid cancers, the total number rises from 230 to 850 for incidents and from 120 to 650 for mortalities. Fatalities due to worker exposure and mandatory evacuation have been reported to be around 610 increasing total estimated mortalities to 730-1260. These estimates are 2.8 times higher than previously reported ones for radiocaesium and (131)I and 16% higher than those reported based on radiocaesium only. Total expected fatalities from Fukushima are 32% lower than in the winter scenario, 5% that in the summer scenario and 30% lower than in the autumn scenario. Nevertheless, cancer fatalities are expected to be less than 5% of those from the tsunami (~20,000).

Resuspension and atmospheric transport of radionuclides due to wildfires near the Chernobyl Nuclear Power Plant in 2015: An impact assessment

In April and August 2015, two major fires in the Chernobyl Exclusion Zone (CEZ) caused concerns about the secondary radioactive contamination that might have spread over Europe. The present paper assessed, for the first time, the impact of these fires over Europe. About 10.9 TBq of 137Cs, 1.5 TBq of 90Sr, 7.8 GBq of 238Pu, 6.3 GBq of 239Pu, 9.4 GBq of 240Pu and 29.7 GBq of 241Am were released from both fire events corresponding to a serious event. The more labile elements escaped easier from the CEZ, whereas the larger refractory particles were removed more efficiently from the atmosphere mainly affecting the CEZ and its vicinity. During the spring 2015 fires, about 93% of the labile and 97% of the refractory particles ended in Eastern European countries. Similarly, during the summer 2015 fires, about 75% of the labile and 59% of the refractory radionuclides were exported from the CEZ with the majority depositing in Belarus and Russia. Effective doses were above 1 mSv y−1 in the CEZ, but much lower in the rest of Europe contributing an additional dose to the Eastern European population, which is far below a dose from a medical X-ray.

The concentration of 137Cs in the surface of the Greek marine environment

The radiological status of the Greek marine environment, prior to the Chernobyl accident, was characterized mainly by the fallout from nuclear weapon tests. However, the release of radioactivity into the environment from the accident in the Chernobyl Nuclear Power Plant and its deposition in the Greek marine environment resulted in an increase of the (137)Cs activity concentration by approximately one order of magnitude. In addition, the direct transport of radiocaesium into the North Aegean Sea has been further influenced by the late impact of the Chernobyl accident on the Greek marine environment, related to the transfer of (137)Cs, mainly through the Dnieper but also the Danube rivers, to the Black Sea and further to the North Aegean Sea through the Straits of Dardanelles. The aim of this work is to provide a present day picture of the geographic variation of the concentration of (137)Cs in the surface layer of the Greek marine environment and hence, to evaluate the annual committed effective dose delivered to humans through the ingestion pathway from marine sources.

Black carbon sources constrained by observations in the Russian high Arctic

Understanding the role of short-lived climate forcers such as black carbon (BC) at high northern latitudes in climate change is hampered by the scarcity of surface observations in the Russian Arctic. In this study, highly time-resolved Equivalent BC (EBC) measurements during a ship campaign in the White, Barents, and Kara Seas in October 2015 are presented. The measured EBC concentrations are compared with BC concentrations simulated with a Lagrangian particle dispersion model coupled with a recently completed global emission inventory to quantify the origin of the Arctic BC. EBC showed increased values (100-400 ng m-3) in the Kara Strait, Kara Sea, and Kola Peninsula and an extremely high concentration (1000 ng m-3) in the White Sea. Assessment of BC origin throughout the expedition showed that gas-flaring emissions from the Yamal-Khanty-Mansiysk and Nenets-Komi regions contributed the most when the ship was close to the Kara Strait, north of 70° N. Near Arkhangelsk (White Sea), biomass burning in mid-latitudes, surface transportation, and residential and commercial combustion from Central and Eastern Europe were found to be important BC sources. The model reproduced observed EBC concentrations efficiently, building credibility in the emission inventory for BC emissions at high northern latitudes.