On the use of dated sediments to investigate historical nuclear discharges.

Studsvik, a Swedish nuclear research facility, has been releasing aquatic radioactive discharges in the Baltic Sea, through the bay Tvären, since 1959. The permissible discharge levels are regulated by the Swedish Radiation Safety Authority (SSM) but only information about 60Co, 137Cs, 152Eu, total alpha and beta activities were reported up to 2002. Since then, the reports cover most a more comprehensive set of radionuclides. In this context, the seabed can be utilized as a chronological archive to investigate historical Studsvik releases. To this end, 23 sediment cores covering the whole area of the bay were studied and 5 of them were dated using 210Pb-dating methods. Since the discharges from Studsvik contain both plutonium and caesium, neither can be used to validate the 210Pb-dating method. Instead, stable lead with maximum deposition, known to be dated to 1970, was used. Cobalt-60, 137Cs, and 152Eu depth distributions were studied from the dated sediment cores and compared with reported levels of aquatic discharges. The expected sediment 137Cs-peak from the fallout from the Chornobyl accident was however smeared out, indicating an ongoing inflow of 137Cs with the Baltic seawater. Our findings show that reported releases of aquatic discharges of 60Co and 152Eu are consistent with measured sediment activity distribution. The sediments from the deepest parts of Tvären, with intact chronology and with a high time resolution, are ideal for investigating historical nuclear discharges and can be a tool to investigate unreported radionuclide releases. Dated sediment can in this way be a tool for nuclear safeguards to evaluate past and present activities in nuclear facilities.

On the radiotoxic 210Po in coffee beans worldwide and the impact of roasting and brewing on its extraction into beverages: from the experiments to 210Po content prediction.

We determined radiotoxic 210Po in roasted coffee beans from different regions worldwide, the beverages, and tried to create the prediction model of 210Po content based on its growth location. Additionally, the experiments on 210Po losses and extraction were performed to describe the actual exposure to 210Po. 210Po concentrations in coffee beans and brews tuned out low (maximally of 0.20 Bq∙kg-1 and 2.31 Bq∙L-1, respectively). We assessed the impact of the roasting process on 210Po content and its losses at a maximum of 56.7%. During infusion experiments, we estimated the extraction of 210Po to the coffee brew at a maximum of 40.6%. The amount of 210Po in the coffee brew depended on the infusion style and water type. We calculated the effective radiation doses from the coffee drink ingestion. Coffee drinking does not contribute significantly to the annual effective radiation dose worldwide.

Plutonium Signatures in a Dated Sediment Core as a Tool to Reveal Nuclear Sources in the Baltic Sea.

Plutonium distribution was studied in an undisturbed sediment core sampled from the Tvären bay in the vicinity of the Studsvik nuclear facility in Sweden. The complete analysis, including minor isotopes, of the Pu isotope composition (238Pu, 239Pu, 240Pu, 241Pu, 242Pu, and 244Pu) allowed us to establish the Pu origin in this area of the Baltic Sea and to reconstruct the Studsvik aquatic release history. The results show highly enriched 239Pu, probably originating from the Swedish nuclear program in the 1960s and 1970s and the handling of high burn-up nuclear fuel in the later years. In addition, the 244Pu/239Pu atomic ratio for the global fallout period between 1958 and 1965 is suggested to be (7.94 ± 0.31)·10-5. In the bottom layer of the sediment, dated 1953-1957, we detected a higher average 244Pu/239Pu ratio of (1.51 ± 0.11)·10-4, indicating the possible impact of the first US thermonuclear tests (1952-1958).

Estimation of plutonium 241Pu budget in the Gulf of Gdansk and the Gdansk Basin (the southern Baltic Sea).

Presented have been the results of inventory estimation of anthropogenic beta-emitting 241Pu, in different components in the southern Baltic Sea ecosystem. The total 241Pu activity present in the Gulf of Gdansk and the Gdansk Basin for 2021 was estimated at 1.99 TBq and 7.82 TBq, respectively, of which 1.59 TBq and 6.38 TBq in the sediments. The Vistula and the Neman River and the atmospheric fallout were distinguished as the primary sources of plutonium in these basins. In seawater of the Gulf of Gdansk, there was about 0.40 TBq 241Pu (20.1% of total activity) and 1.44 TBq 241Pu (18.4% of total activity) in the Gdansk Basin. The 241Pu accumulated in living organisms in 2021 was 1.13 GBq in the Gulf of Gdansk and 3.96 GBq in the Gdansk Basin. In the Gulf of Gdansk biota, 55.7% was accumulated in zoobenthos, while in the Gdansk Basin, 48.3% was in zoobenthos.

Total dissolution of environmental samples for the determination of uranium and thorium by ICP-MS and alpha-particle spectrometry.

A low-cost total dissolution method for accurate determination of uranium and thorium isotopes in environmental samples (soil and sediment) was introduced, optimised and validated. The method included alkaline fusion based on sodium hydroxide (NaOH) and sodium peroxide (Na2O2), followed by sequential extraction chromatography separation and measurements with ICP-MS or alpha-particle spectrometry. The overall chemical recoveries for U and Th for the entire procedure were about 80% and 90%, respectively. The 238U contribution from partial dissolution of the nickel crucibles accounted for about 80% of the total background activity.

210Po and 210Pb in King Bolete (Boletus edulis) and Related Mushroom Species: Estimated Effective Radiation Dose and Geospatial Distribution in Central and Eastern Europe.

210Po and 210Pb occur naturally and are the most radiotoxic isotopes of the uranium (U) decay chain. Samples of Boletus edulis and related mushroom species, including B. pinophilus, B. reticulatus, B. luridus and B. impolitus, collected from Poland and Belarus were investigated for the activity concentrations of these isotopes and also for their potential health risk through adult human consumption. The results showed that spatially, the occurrence of 210Po and 210Po was heterogeneous, with activities varying from 0.91 to 4.47 Bq∙kg-1 dry biomass and from 0.82 to 5.82 Bq∙kg-1 db, respectively. Caps and stipes of the fruiting bodies showed similar levels of contamination. Consumption of boletes foraged in Poland could result in exposure to a combined radiation dose of 10 µSv∙kg-1 db from both isotopes. This dose is not significant compared to the total annual effective radiation dose of 210Po and 210Pb (54-471 µSv∙kg-1) from all sources, suggesting that these mushrooms are comparatively safe for human consumption.

Development of 148Gd analysis method using stable Gd.

The analytical method of Gd determination was developed with the aim to analyse 148Gd in environmental and bioassay samples. It involves the use of anion exchange resin, extraction chromatography, and cation exchange resin. Alkaline fusion and calcium oxalate co-precipitation are used for solid samples dissolution and liquid samples preconcentration, respectively. Total method recovery was tested with natural Gd (157Gd) using ICP-QQQ-MS. A maximum total recovery of 75 % was obtained.

Bolete mushroom Boletus bainiugan from Yunnan as a reflection of the geographical distribution of 210Po, 210Pb and uranium (234U, 235U, 238U) radionuclides, their intake rates and effective exposure doses.

This pioneering study aimed to determine the activity concentrations of 210Po, 210Pb and uranium (234U, 235U, 238U) radionuclides in fruit bodies of wild bolete Boletus bainiugan Dentinger and to estimate its edible safety, which may give scientific evidence for the consumption of this species. The analyses were performed using alpha spectrometer after digestion, exchange resins separation and deposition. Measurement data were analysed and interpolation maps reflecting 210Po, 210Pb and uranium (234U, 235U, 238U) geographical distribution in Yunnan province (China) were presented. In addition, from the perspective of food safety, the possible related effective radiation dose to mushrooms consumers were estimated. The results indicated that 210Po, 210Pb and uranium (234U, 235U, 238U) radionuclides contents in B. bainiugan were significantly different with respect to geographical distribution, and their possible intake in a part of the region was considerably higher. A very interesting observation was done according to the values of 235U/238U activity ratio indicating the occurrence of uranium faction from the global fallout of nuclear weapon tests.

The level of 210Pb extraction efficiency in Polish herbal teas and the possible effective dose to consumers.

The article presents the results of a study on the level of 210Pb efficiency extraction in Polish herbal teas as a possible additional source of this radioactive isotope in the human diet. The twelve most popular herbal teas available in Poland and their infusions in filtered and tap water were analyzed as well as 210Pb activity concentrations and effective doses (radiation) were calculated. The highest activity concentration of 210Pb in dried plants was determined in cistus - 35.5 Bq kg-1 dry wt, while the lowest was in milk thistle - 3.25 Bq kg-1 dry wt what gives respectively for cistus 46.1 ± 0.7 and 6.50 ± 0.29 mBq for milk thistle per one tea bag. The extraction efficiencies in the filtered water oscillated from 5.1 ± 0.5 for milk thistle to 27.3 ± 0.8% for cistus, while for the tap water they ranged from 7.3 ± 0.6% for lime to 33.3 ± 2.2% for white mulberry. Based on the study, it was found that the analyzed herbal tea consumption would give a small portion of the annual effective dose of 210Pb received in Poland - the annual effective radiation dose of 210Pb taken with herbal tea infusions (one glass daily) was calculated from 0.08 ± 0.01 to 3.17 ± 0.08 µSv.

Is ecological food also radioecological? - 210Po and 210Pb studies.

Presented are results of a study on accumulation of naturally occurring 210Po and 210Pb in ecological and conventional farming food products in Poland: fruits, vegetables and cereals. The main idea behind this research was to determine the activity concentrations of 210Po and 210Pb in ecological and commercial food as well as calculate and compare the effective dose (radiation) connected to different origin of analyzed food products consumption. The studies showed the majority of all compared food samples contained similar 210Po and 210Pb activities and statistically, the consumption of organic and commercial food would give similar annual effective dose.

On the distribution and inventories of radionuclides in dated sediments around the Swedish coast.

The activity concentrations and distribution of 137Cs, 238Pu, 239+240Pu, 241Am, and 210Pb was determined by the analysis of six sediment cores from the Baltic Sea and Kattegat. The chronology of the sediment cores has been used to evaluate the origin and time trend of the radionuclide sources in these sediments. The sediment cores were dated with a 210Pb model and the results were validated with fallout peaks, assumed to originate from the global nuclear weapons testing and the Chernobyl accident. Source identification, using the isotopic and radionuclide activity ratios, showed that the Chernobyl accident is the main source of 137Cs in the Baltic Sea; for 239+240Pu and 241Am the dominant source was shown to be fallout from nuclear weapons tests. For 238Pu and 241Am the Chernobyl accident had a significant impact on the direct fallout into the Baltic Proper, with up to a 65% contribution in the sediment slices dated to 1986. In these sediment slices the maximum activity ratios of 238Pu/239+240Pu and 241Am/239+240Pu were 0.314 ± 0.008 and 1.29 ± 0.06, respectively. The ratios clearly deviate from the corresponding ratios for global nuclear weapons fallout (around 0.028 and 0.54, respectively). Calculated inventories were 63-175 Bq·m-2 for 239+240Pu, 2.8-7.8 for 238Pu Bq·m-2 and 0.92-44.4 kBq·m-2 for 137Cs. Different fallout patterns for 137Cs and plutonium isotopes from the Chernobyl accident were confirmed through depth profiles analyses. The maximum inventory of 137Cs was observed in the Bothnian Sea, while Chernobyl-derived plutonium was found to be mostly present in Northern Baltic Proper. The radionuclides distribution in the depth profiles shows how contaminated water affects the sediment as it passes sampling stations according to the current circulation pattern in the Baltic Sea. Additionally, the effect of increased activity concentrations from of river discharges in the most contaminated area in the Bothnian Sea was observed.

210Po and 210Pb bioaccumulation and possible related dose assessment in parasol mushroom (Macrolepiota procera).

Presented are results of a study on accumulation and distribution of 210Po and 210Pb in the fruitbodies of parasol mushroom (Macrolepiota procera) and risk to human consumer due to exposure from highly radiotoxic decay particles emitted by both radionuclides. Mushrooms were collected from 16 forested places in central and northern regions of Poland. Activity concentrations of 210Po and 210Pb were determined after radiochemical separation of nuclides and subsequent measurement using validated method and alpha spectrometer. Results showed on spatially heterogeneous distribution of the 210Po and 210Po activity concentrations in M. procera and two interpolation maps were prepared. Activity concentrations of nuclides in dried caps of M. procera were in the range from 3.38 ± 0.41 to 16.70 ± 0.33 Bq∙210Po ∙kg-1 and from 5.11 ± 0.21 to 13.42 ± 0.30 Bq∙210Pb ∙kg-1. Consumption of M. procera foraged in central and northern Poland should not contribute significantly to the annual effective radiation doses from 210Po and 210Pb due to amount of both nuclides accumulated by fungus in caps.

A study on possible use of Urtica dioica (common nettle) plants as uranium (234U, 238U) contamination bioindicator near phosphogypsum stockpile.

The aim of this study was to determine uranium concentrations in common nettle (Urtica dioica) plants and corresponding soils samples which were collected from the area of phosphogypsum stockpile in Wislinka (northern Poland). The uranium concentrations in roots depended on its concentrations in soils. Calculated BCF and TF values showed that soils characteristics and air deposition affect uranium absorption and that different uranium species have different affinities to U. dioica plants. The values of 234U/238U activity ratio indicate natural origin of these radioisotopes in analyzed plants. Uranium concentration in plants roots is negatively weakly correlated with distance from phosphogypsum stockpile.

The radiological impact of phosphogypsum stockpile in Wislinka (northern Poland) on the Martwa Wisla river water.

The aim of this work was to determine the concentrations of uranium (234U, 235U, 238U), polonium (210Po) and lead (210Pb) radioisotopes in water samples and to explore the impact of the phosphogypsum stack on the Martwa Wisla waters. The 238U, 210Po and 210Pb concentrations in analyzed water samples reached maximum values of 11.7 ± 0.3, 2.0 ± 0.1 and 3.2 ± 0.1 mBq L-1 and activity ratios were maximally 1.18 ± 0.01 for 234U/238U, 0.041 ± 0.018 for 235U/238U and 0.69 ± 0.10 for 210Po/210Pb. The obtained results suggest that this impact is rather insignificant and does not affect significantly the Martwa Wisla river.

A study on possible use of Urtica dioica (common nettle) plant as polonium (210)Po and lead (210)Pb contamination biomonitor in the area of phosphogypsum stockpile.

The aim of this study was to test a possible use of Urtica dioica (common nettle) plant as a biomonitor of polonium (210)Po and lead (210)Pb contamination near phosphogypsum stacks by determining concentrations of these radionuclides in samples collected from the area of phosphogypsum stockpile in Wislinka (northern Poland). The (210)Po and (210)Pb contents in roots depended on their concentrations in soils. Bioconcentration factor values from soil to root of the plant did not depend on (210)Po and (210)Pb contents in soils that leads to the conclusion that different polonium and lead species have different affinities to U. dioica plants. The main sources of both analyzed radionuclides in green parts of plants are wet and dry air deposition and transportation from soil. The values of (210)Po/(210)Pb activity ratio indicate natural origin of these radioisotopes in analyzed plants. (210)Po and (210)Pb concentration in U. dioica roots is negatively weakly correlated with distance from phosphogypsum stockpile.

Uranium ((234)U, (235)U and (238)U) contamination of the environment surrounding phosphogypsum waste heap in Wislinka (northern Poland).

The aim of this work was to determine the uranium concentration ((234)U, (235)U and (238)U) and values of the activity ratio (234)U/(238)U in soil samples collected near phosphogypsum waste heap in Wislinka (northern Poland). On the basis of the studies it was found that the values of the (234)U/(238)U activity ratio in the analyzed soils collected in the vicinity of phosphogypsum dump in Wislinka are in most cases close to one and indicate the phosphogypsum origin of the analyzed nuclides. The obtained results of uranium concentrations are however much lower than in previous years before closing of the phosphogypsum stockpile. After this process and covering the phosphogypsum stockpile in Wislinka with sewage sludge, phosphogypsum particles are successfully immobilized. In the light of the results the use of phosphate fertilizers seems to be a major problem. Prolonged and heavy rains can cause leaching accumulated uranium isotopes in the phosphogypsum stockpile, which will be washed into the Martwa Wisla and on the fields in the immediate vicinity of this storage.

A study on lead (210Pb) and polonium (210Po) contamination from phosphogypsum in the environment of Wislinka (northern Poland).

The results of polonium ((210)Po) and lead ((210)Pb) determination in different environmental soil samples collected in the vicinity of the phosphogypsum stack in Wislinka (northern Poland) are presented and discussed in this paper. The (210)Po and (210)Pb concentrations in soil samples from the phosphogypsum stack recorded in this study are significantly higher only in areas that are close to the heap. The relationship between atmospheric deposition and elevated analyzed radionuclides concentrations in top soil layers, especially in the vicinity of the phosphogypsum stack, was showed in this study. (210)Po and (210)Pb radionuclides were detected in concentrations which could have harmful effects on human health or the environment. The considerably high concentrations of (210)Po and (210)Pb in soil samples collected from the vicinity of the phosphogypsum stack obtained in this study can lead to the conclusion that the presently undertaken recultivation process is successful and the 300 m(2) protection zone around the phosphogypsum stack seems to be able to offset the negative influence of the phosphogypsum stack on the surrounding environment.

Polonium (²¹°Po), uranium (²³4U, ²³8U) isotopes and trace metals in mosses from Sobieszewo Island, northern Poland.

The activity of polonium (210)Po and uranium (234)U, (238)U radionuclides, as well as trace metals in mosses, collected from Sobieszewo Island area (northern Poland), were determined using the alpha spectrometry, AAS (atomic absorption spectrometry) and OES-ICP (atomic emission spectrometry with inductively coupled plasma). The concentrations of mercury (directly from the solid sample) were determined by the cold vapor technique of CV AAS. The obtained results revealed that the concentrations of (210)Po, (234)U, and (238)U in the two analyzed kinds of mosses: schrebers big red stem moss (Pleurozium schreberi) and broom moss (Dicranum scoparium) were similar. The higher polonium concentrations were found in broom moss (Dicranum scoparium), but uranium concentrations were relatively low for both species of analyzed mosses. Among the analyzed trace metals the highest concentration in mosses was recorded for iron, while the lowest for nickel, cadmium and mercury. The obtained studies showed that the sources of polonium and uranium isotopes, as well as trace metals in analyzed mosses are air city contaminations transported from Gdansk and from existing in the vicinity the phosphogypsum waste heap in Wislinka (near Gdansk).

The radiochemical contamination (²¹°Po and ²³8U) of zone around phosphogypsum waste heap in Wislinka (northern Poland).

The aim of this work was the determination of the impact of phosphogypsum waste heap in Wislinka (northern Poland) for radiological protection of zone around waste heap. These studies are very important for the estimation of natural alpha radionuclides contents in the vicinity of phosphogypsum waste heap and for environmental pollution assessment of this area. The process of bioaccumulation of radionuclides in interior plants parts prove to examine their origin sources, too. The activity of (210)Po, (234)U, and (238)U were measured using an alpha spectrometer. The values of uranium and polonium concentration in water with immediate area of waste heap are considerably higher than in the waters of the Martwa Wisla river. The values of activity ratio (234)U/(238)U are approximately about one in the phosphogypsum (0.97 ± 0.05) and in the water of retention reservoir and pumping station (0.92 ± 0.01 and 0.99 ± 0.08), while in the water from the Martwa Wisla river they are slightly higher than one (1.03 ± 0.07 and 1.17 ± 0.06). In the analyzed plants species the highest amounts of polonium and uranium were found in ruderal plants samples (between 51 ± 1 and 89 ± 1 for (210)Po; between 36 ± 3 and 68 ± 3 for (238)U) as well as hygrophilous plant samples (18 ± 1 and 84 ± 3; 42 ± 2 and 130 ± 4, respectively for (210)Po and (238)U). The more amounts of (210)Po and (238)U radionuclides were accumulated mainly in the roots of plant species in comparison to green parts. The general conclusion of realized study is higher influence of phosphogypsum on radioactive contamination of environmental zone around heap waste in Wislinka (northern Poland).