Long term investigation of 137Cs in chicken meat and eggs from northwest Croatia

Abstract

This paper presents the results of long-term investigations of ¹³⁷Cs activity concentrations in chicken meat and eggs from northwest Croatia for the period 1987–2018. The research has been done as a part of monitoring program of radioactive contamination in Croatia. The highest activity concentrations in both of these foodstuffs were measured in 1987 and have been decreasing exponentially ever since. The Fukushima-Daiichi accident in 2011 did not cause any increase of ¹³⁷Cs activity concentrations. The ecological half-life for ¹³⁷Cs was estimated to be 8.0 and 8.4?years for chicken meat and eggs respectively. The correlation between ¹³⁷Cs in fallout and chicken meat as well as between ¹³⁷Cs in fallout and eggs is very good, the respective correlation coefficients being 0.79 and 0.72, indicating that fallout was the main source of ¹³⁷Cs contamination in both foodstuffs. The estimated effective doses received by adult members of the Croatian population due to the intake of radiocaesium by chicken meat and egg consumption for the overall observed period are very small, 2.0 and 0.6 µSv respectively. Therefore, chicken meat and chicken egg consumption was not a critical pathway for the transfer of radiocaesium to humans.     

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

Background  

The fallout of artificially produced radioactive isotopes has been recorded at a site in southern West Siberia (54°50′43.6″ N, 083°06′22.4″ E, Novosibirsk, Russia).     

Radioactive isotope uptake in a grass-legume association

The radioactive uptake of Medicago sativa and Rye grass in a pasture exposed to the fallout from the Chernobyl reactor accident, was determined in four consecutive harvests covering a period of one year after the accident,In plants of Medicago sativa, inoculated with an effective Rhizobia meliloti strain isolated from Greek soils, a high degree of biological nitrogen fixation was observed at all harvests using N-15 techniques. At the second and third harvests, the percentage nitrogen derived from fixation (%NdfF), the percentage nitrogen derived from soil (%NdfS), as well as the radioactive uptake from the soil remained stable. At the fourth harvest, however, the %NdfF decreased while the %NdfS and the radioactive uptake from soil significantly increased. At the first harvest the radioactivity in both plants, caused mainly by direct fallout contamination, was considerably higher than that observed at the later harvests. Medicago sativa contained significantly less radioactivity than the grass at all harvests, although both plants were grown under the same environmental conditions. Even at the fourth harvest, almost one year after the initial contamination, the radioactivity of grass remained at high levels ( 20 Bq g(-1) of protein) while in Medicago sativa it assumed considerably lower values (3.6 Bq g(-1) of protein). A possible involvement of biological nitrogen fixation in the reduction of radioactive uptake is discussed. Finally, certain practical conclusions are drawn with respect to a safer management of pastures exposed to radioactivity.     

The occurrence and bioavailability of radioactive 137Cs in small forest lakes in Southern Finland

Following the Chernobyl accident in late April 1986, central Finland was subjected to considerable radioactive fallout. The radioactive isotope of caesium, (137)Cs, was potentially the most harmful isotope in the fallout because of its long half-life (30 years). (137)Cs activities remained unexpectedly low within the biota (algae, zooplankton, aquatic moss, fish) of some humic forest lakes in southern Finland compared to the clear water lakes within the same district. This observation suggested that humic substances, by binding (137)Cs chemically, may reduce its bioavailability in lake water. Our laboratory experiments (throughflow systems; gel chromatography) demonstrated that binding of (137)Cs by humic substances was negligible in untreated lake waters; only when most of the alkali metals had been removed with an ion exchange resin was any binding of (137)Cs by low molecular humic fractions apparent. Instead, the concentrations of cations (especially potassium) were of overwhelming importance for the bioavailability of (137)Cs within the lacustrine ecosystems. The concentrations of (137)Cs within food chains are expected to stay at a high level for many years especially in lakes with long water renewal times.     

A study of the movement of radioactive material released during the Windscale fire in October 1957 using ERA40 data

In October 1957 a fire in Pile Number 1, a nuclear reactor at the Windscale Works, Sellafield, resulted in the accidental release of radionuclides to the atmosphere. Previous studies have described the atmospheric transport of the resultant radioactive plume from its release on the Cumbrian coast of Northwest England to its passage across mainland Europe. Those past studies have suffered from uncertainties concerning the quantity and timing of emissions and meteorological conditions. Crabtree [1959. The travel and diffusion of the radioactive material emitted during the Windscale accident. Quarterly Journal of the Royal Meteorological Society 85, 362] initially produced estimates of plume transport based on weather observations and radiosonde profiles. Later, ApSimon et al. [1985. Long-range atmospheric dispersion of radioisotopes—I. The MESOS model. Atmospheric Environment 19(1), 99–111] based estimates of plume transport on trajectories calculated from weather charts. More recently, Nelson et al. [2006. A study of the movement of radioactive material discharged during the Windscale fire in October 1957. Atmospheric Environment, 40, 58–75] used a full three-dimensional dispersion model using digitised weather data from similar charts.This study aims to further reduce uncertainty in the plume's behaviour by using the latest available Numerical Weather Prediction Model reanalysis of meteorological data from the European Centre for Medium Range Weather Forecasts (ERA-40) coupled with current best estimates of the radioactive emissions profile. The results presented here generally support the findings of previous studies though an improvement in model comparisons against observational measurements has been found. The opportunity was also taken to extend the time horizon, and hence geographical coverage, of the modelled plume. It is considered that this paper presents the best estimate to date of the plume's behaviour.     

The potential of lichens as long-term biomonitors of natural and artificial radionuclides

Lichens were used as biomonitors of Chernobyl fallout 137Cs, of cosmogenic 7Be and of radioactive members of the natural uranium and thorium decay chains. Samples were taken from two locations in France, including lichens sampled at different distances of a coal fired power plant and close to a uranium ore processing waste disposal site. All samples were analyzed gamma-spectrometrically after equilibrium concentrations of short-lived isotopes had been attained. Activity concentrations of the members of the uranium and thorium decay chains in Parmelia sulcata sampled 1994 decrease with distance from the plant, whereas in lichens taken at the waste disposal site a decrease with time was observed. Comparison of 7Be activity concentrations measured in lichens with atmospheric deposition rates confirms that P. sulcata can be used as a quantitative biomonitor of radioactive trace substances. Retention half-lives calculated with a simple one-compartment model are 2.6 +/- 1.2 years for cesium, which was detected in all samples even more than a decade after the Chernobyl accident, and of 0.7 (+/- 0.1) to 3.3 (+/- 0.7) years for lead. Consequences of our results for model identifiability and parameter estimation of a two-compartment model are discussed.     

Eliminating Mechanical Shaking of Dust Filter Bags

The feasibility of open burning under selected meteorological conditions is discussed. Meteorological provisos and nonmeteorological factors are enumerated. Topics discussed include: combustion, fuel moisture, fire hazard, forecasting, fallout and odor, and air pollution potential. A mathematical estimate of visibility reduction is described and evaluated. A procedure for estimating atmospheric ventilation is presented. The author concludes that most massive open fires result in adverse effects on either a local or areawide scale. Hence, the best meteorological decision possible is frequently one that minimizes one scale of effect at the expense of the other.     

Radionuclide content of Las Vegas Wash sediments

The Las Vegas Wash is an excavated waterway channel which drains all surface water and effluent discharge from sewage-treatment facilitates from the greater Las Vegas Metropolitan Area to Lake Mead. Fine and course sediment samples were collected at 100-m intervals and analyzed to determine the distribution of gamma-emitting radionuclides in the lower 5,500 m of the Las Vegas Wash. Results indicate depletion of long-lived fission products in upstream Wash sediments. However, trace levels of ¹³⁷Cs measured in downstream sediments suggest the resuspension and transport of radioactive fallout within the Wash. Levels of ⁴⁰K, ²³²Th, ²³⁵U, and ²³⁸U found in Wash sediments were consistent with levels typically found in southeast Nevada soils.     

Herbicides and nitrogen in precipitation: progression from west to east and contribution to the Marne river (France)

Herbicides and nitrogen fallout were studied in France at six sites from west to east. Atrazine, a herbicide widely used in France and forbidden in some European countries was found. Its fallout was quantified to 400 kg on the river Marne catchment (13 500 km2), an agricultural region located east of Paris. The average fallout contribution to the Marne river contamination was estimated at 20 ng/l from March to August. Independently of the wind direction, only a small part of this atmospheric contamination can reach adjacent countries.     

Ecological half-life of caesium in roe deer (Capreolus capreolus)

Biological half-lives for various radionuclides have been determined for many animals kept in the laboratory or under controlled conditions. Only occasionally has been it possible to determine the ecological half-lives of radionuclides in wild animals, where the contamination has occurred in their natural habitats. Following the fallout from the Chernobyl accident and its subsequent ingestion by wildlife, no one knew how long it would take the wild animals to eliminate the radionuclides, and in particular radiocaesium, from their bodies. In this study of roe deer (Capreolus capreolus), bucks (males)were shot at weekly/fortnightly intervals from mid-May till the end of July, as part of the annual cull on an area, which included some young forestry (Stone Chest-National Grid Reference NY48090), planted in 1971/72. The ration of 137Cs:134Cs, typical of the Chernobyl fallout, was seldom observed in these animals due to the highly variable concentrations of 137Cs originating from bomb fallout. Therefore, 134Cs was used instead because its presence was almost entirely due to the Chernobyl fallout. After using log10 transformation of the 134Cs concentrations, a significant (p < 0.01) regression was obtained which accounted for 85% of the variation. From the regression, the ecological half-life for 134Cs was found to be 28.3 days.     

Radiocaesium activity concentrations in potatoes in Croatia after the Chernobyl accident and dose assessment

Systematic investigations of (137)Cs and (134)Cs activity concentrations in potatoes (Solanum tuberosum) for the post-Chernobyl period (1986-2005) in the Republic of Croatia are summarized. The correlation between (137)Cs activity concentrations in fallout and potatoes, has been found to be very good, the correlation coefficient being r = 0.88 with P(t) < 0.001 for 18 degrees of freedom. As the radiocaesium levels in potatoes decreased exponentially, the mean residence time of (137)Cs in potatoes was estimated by fitting the measured activity concentrations to the exponential curve. The mean residence time was found to be 6.8 +/- 1.1 years, the standard deviation being estimated by the Monte Carlo simulations. The initial observed (134)Cs:(137)Cs activity ratio in potatoes has been found to be quite variable, but slightly lesser than the theoretically predicted value of 0.5, calculated by applying the known inventory of these radionuclides in the Chernobyl reactor to the equation for the differential radioactive decay. This can be explained by presence of the pre-Chernobyl (137)Cs in soil that originated from nuclear fallout. The annual effective doses received by (134)Cs and (137)Cs intake due to consumption of potatoes estimated for an adult member of the Croatian population were found to be very small, as the per caput Dose for the entire 1986-2005 period was calculated to be about 2.9 microSv, (134)Cs accounting approximately for 1/3 of the entire dose. Therefore, after the Chernobyl accident consumption of potatoes was not the critical pathway for human intake of radiocaesium from the environment in Croatia.     

Global fallout Pu recorded in lacustrine sediments in Lake Hongfeng, SW China

Studies on the distribution and isotope compositions of fallout Pu are important for source characterization of possible future non-fallout Pu contamination in aquatic environments, and useful for dating of recent sediments to understand the pollution history of environmental contaminants. We present the historical record of atmospheric Pu fallout reconstructed from a sediment core from Lake Hongfeng, China. The Pu activity profile was in agreement with the 137Cs profile. Inventories were 50.7 Bq m(-2) for 239+240Pu and 1586 Bq m(-2) for 137Cs. The average 240Pu/239Pu atom ratio was 0.185+/-0.009, indicating that Pu originated from global stratospheric fallout rather than from direct tropospheric or close-in fallout from the Chinese nuclear testing conducted in the 1970s. Our data suggested that Lake Hongfeng would be an ideal setting for monitoring atmospheric fallout and environmental changes in this region.     

Alkylphenolic compounds and bisphenol A contamination within a heavily urbanized area: case study of Paris

This study evaluates the influence of a heavily urbanized area (Paris Metropolitan area), on receiving water contamination by both bisphenol A (BPA) and alkylphenol ethoxylate (APE) biodegradation product. The study began by investigating concentrations within urban sources. In addition to the more commonly studied wastewater treatment plant effluent, wet weather urban sources (including combined sewer overflows, urban runoff, and total atmospheric fallout) were considered. The initial results highlight a significant contamination of all urban sources (from a few nanograms per liter in atmospheric fallout to several micrograms per liter in the other sources) with clearly distinguishable distribution patterns. Secondly, concentration changes along the Seine River from upstream of the Paris Metropolitan area to downstream were investigated. While the concentrations of BPA and nonylphenoxy acetic acid (NP₁EC) increase substantially due to urban sources, the 4-nonylphenol concentrations remain homogeneous along the Seine. These results suggest a broad dissemination of 4-nonylphenol at the scale of the Seine River basin. Moreover, the relationship between pollutant concentrations and Seine River flow was assessed both upstream and downstream of the Paris conurbation. Consequently, a sharp decrease in dissolved NP₁EC concentrations relative to Seine River flow underscores the influence of single-point urban pollution on Seine River contamination. Conversely, dissolved 4-nonylphenol concentrations serve to reinforce the hypothesis of its widespread presence at the Seine River basin scale.     

137Cs determination and mutagenicity tests in wild Mus musculus domesticus before and after the Chernobyl accident

Wild rodents were collected alive in a suburban area to the north of Rome before, during, 6 months and 1 year after the Chernobyl accident. Radionuclide determinations to assess their content of (137)Cs and mutagenicity tests (bone-marrow micronucleus test and sperm abnormalities assay) were performed on the captured animals. The results obtained for the species Mus musculus domesticus (which was the rodent captured in highest numbers), compared with the results obtained before the fallout, showed an increase of both micronucleated polychromatic erythrocytes (MPCEs/1000 PCEs) and (137)Cs content during and after the fallout.     

Fitting empirical equations to rain scavenging ratios of atmospheric radioactive aerosols

An empirical equation of the type W = ZR^−p has been fitted to daily or monthly rainfall R and scavenging ratio W of bomb fallout and natural Pb-210 at a number of monitoring stations in India. The constants Z and p were evaluated by least squares techniques and have values in the range of 900–3400 and 0.22–0.49, respectively. In spite of these differences, which are partly due to statistical errors of measurements, the empirical equations are sufficiently similar under various conditions to be of value in predicting fallout. They also show the presence of an inverse relation between scavenging ratio and rainfall amount.     

Studies on Sulfuric Acid Mist Downwind from a Sulfuric Acid Manufacturing Plant

Air pollution downstream from a sulfuric acid manufacturing plant is comprised of two aspects, the amount of acid mist fallout and the concentration in the atmosphere. This investigation shows that it is desirable to determine each of these by an independent method of collection. Pans of distilled water were used to collect and determine the sulfuric acid mist fallout and an electrostatic precipitator was used to determine the sulfuric acid mist concentration in the atmosphere. The use of Stokes’ Law to convert the results obtained by one method to those obtained by the other requires a knowledge of the particle size of the sulfuric acid mist droplets. Data presented show that tho uso of an average particle size can yield a picture of pollution which is in error by many orders of magnitude. The study shows that areas adjacent to a plant may be subjected to fallout of rather large particle size when there are not adequate methods for removal from the emission or byproduct gases.     

Radioactivity levels in a firn core from the Yukon Territory,Canada

Gross β-activity and tritium concentration measurements made on a 26.8m length of consolidated snow (firn) core retrieved from an altitude of 5340 m on Mt. Logan (Yukon Territory, Canada) have revealed a detailed chronology of natural and anthropogenic radioactivity levels extending from about 1943 to 1980. Oxygen isotope measurements were used to assist in the dating of the core and a reliable time scale spanning 1950–1980 has been established with an accuracy of at least ± 0.5 y, and in some cases ± 0.25y.An immediate result is the establishment of mean annual accumulation rates, which are, for the years 1963–1980: 0.36m y⁻¹ and for 1951–1980: 0.39m y⁻ water equivalent. Another result is the estimation of the ‘stratospheric residence time’ for the fission fallout products (mainly ⁹⁰Sr and ¹³⁷Cs). A value of the stratospheric residence time of about 1 y is derived from data spanning 1963–1967.Reference to the history of atmospheric thermonuclear device testing shows that individual or specific groups of tests by different countries can be identified.Comparison of the gross β-activity data with a similar set from Station Centrale (Greenland) shows that although the same trends exist in the two data sets, the amplitude of most corresponding major peaks in the Greenland data is significantly lower. Since the accumulation rates at the two sites are almost identical and since the deposition of radioactive aerosols in any case is expected to be dominated by dry fall-out, the differences are assumed to be related to the trajectory path and to the diffusion rates of the radionuclide clouds.     

Refining fire emissions for air quality modeling with remotely sensed fire counts: A wildfire case study

This paper examines the use of Moderate Resolution Imaging Spectroradiometer (MODIS) observed active fire data (pixel counts) to refine the National Emissions Inventory (NEI) fire emission estimates for major wildfire events. This study was motivated by the extremely limited information available for many years of the United States Environmental Protection Agency (US EPA) NEI about the specific location and timing of major fire events. The MODIS fire data provide twice-daily snapshots of the locations and breadth of fires, which can be helpful for identifying major wildfires that typically persist for a minimum of several days. A major wildfire in Mallory Swamp, FL, is used here as a case study to test a reallocation approach for temporally and spatially distributing the state-level fire emissions based on the MODIS fire data. Community Multiscale Air Quality (CMAQ) model simulations using these reallocated emissions are then compared with another simulation based on the original NEI fire emissions. We compare total carbon (TC) predictions from these CMAQ simulations against observations from the Inter-agency Monitoring of Protected Visual Environments (IMPROVE) surface network. Comparisons at three IMPROVE sites demonstrate substantial improvements in the temporal variability and overall correlation for TC predictions when the MODIS fire data is used to refine the fire emission estimates. These results suggest that if limited information is available about the spatial and temporal extent of a major wildfire fire, remotely sensed fire data can be a useful surrogate for developing the fire emissions estimates for air quality modeling purposes.     

Scavenging of electrified radioactive aerosol

Scavenging by water droplets is a mechanism for aerosol removal near clouds. Numerical methods are developed to quantify the removal of charged radioactive aerosols, including the electrical image force's contribution, attractive at small separations. Charging of radioactive aerosols is found to have significant effects on their collision efficiency and scavenging coefficient. The effect depends on the aerosol charge, and therefore, on the radioactive aerosol's decay rate and number concentration, but it does not depend significantly on the charge carried by the water drops. Scavenging coefficients are calculated for radioactive aerosols. For small particles at low aerosol concentrations (Z∼10–100 cm⁻³), charging can increase the scavenging coefficients by up to an order of magnitude. Electrification will, therefore, encourage the removal of small radioactive aerosols from the atmosphere, more rapidly than equivalent non-radioactive aerosols. The increase in removal at low radioactive-aerosol concentration may account for underpredictions of surface concentrations and will contribute to spatial variations in aerosol removal.     

Nuclear Weapons Tests and Environmental Consequences: A Global Perspective

The beginning of the atomic age marked the outset of nuclear weapons testing, which is responsible for the radioactive contamination of a large number of sites worldwide. The paper aims to analyze nuclear weapons tests conducted in the second half of the twentieth century, highlighting the impact of radioactive pollution on the atmospheric, aquatic, and underground environments. Special attention was given to the concentration of main radioactive isotopes which were released, such as ¹⁴C, ¹³⁷Cs, and ⁹⁰Sr, generally stored in the atmosphere and marine environment. In addition, an attempt was made to trace the spatial delimitation of the most heavily contaminated sites worldwide, and to note the human exposure which has caused a significantly increased incidence of thyroidal cancer locally and regionally. The United States is one of the important examples of assessing the correlation between the increase in the thyroid cancer incidence rate and the continental-scale radioactive contamination with ¹³¹I, a radioactive isotope which was released in large amounts during the nuclear tests carried out in the main test site, Nevada.