Water Activity Content Research Articles

Development and Characterization of High-Energy Protein Bars with Enhanced Antioxidant, Chemical, Nutritional, Physical, and Sensory Properties.

Protein-rich energy bars are known as an excellent nutritional supplement for athletes that help to build and repair connective tissues. The study is, therefore, aimed at developing high-protein bars using lupine seeds, wheat germ, and selected dried fruits including raisins, dates, apricots, and cranberries. Different formulations (F1, F2, F3, and F4) were performed at different ratios of ingredients to produce high-protein bars and compared them with a control bar made of whey-protein concentrate and oat flakes. For this purpose, a proximate analysis, total phenol content, total flavonoid content, DPPH radical scavenging activity, water content, nutritional, and sensory analysis was performed to evaluate the results. The proximate analysis of the produced protein bars showed a significantly higher protein content (22 ± 2) and total phenolic activity (57 ± 33) in formulation group 4 as compared to the other groups. Furthermore, the least water activity content was found in formulation group 1 (1 ± 0.0) when compared with the control group (1 ± 0.0). The results from the sensory evaluation revealed that T3 had the highest average scores in overall consumer acceptability. Our study found that total phenolic, flavonoid, and fiber content were significantly higher in the prepared protein bars indicating prospective health benefits when compared to the control group. Overall, the study demonstrates that high-protein bars using functional ingredients like dried fruit can provide enriched nutritionally valuable food options for consumers.

Risk assessment from radon in domestic water for the Greek population.

This study focused on assessing the risk from the exposure to radon contained in domestic water for a significant part (~20%) of the Greek population. Also, the variation of radon in domestic water was monitored from 2017 to 2023 in certain villages that showed relatively high radon levels and relied on boreholes for their water supply. The radon in domestic water activity concentrations measured in the investigated Greek places ranged from lower than the minimum detection limit (2BqL-1) levels up to 187BqL-1 with an average value of 9.1BqL-1. Overall, higher radon in domestic water activity concentrations were observed in places supplied from boreholes located inside granitic and metamorphic rock areas. Only one out of the 487 examined places, which accounts for 0.015% of the examined Greek population, showed an average radon-in-water activity concentration higher than the parametric value of 100BqL-1 adopted by Greece following the EURATOM Directive (2013/51/EURATOM). Therefore, radon-in-water does not pose a health concern (risk) for the investigated Greek population. The total (inhalation and ingestion) annual effective doses to adults, corresponding to the measured radon-in-water activity concentrations, ranged from nearly 0 to 1.20mSv y-1 with an average value of 0.059mSv y-1, while for children, they ranged from almost 0 to 1.26mSv y-1 with an average value of 0.061mSv y-1. Regarding the variation of radon in domestic water monitoring, places supplied with water from one borehole showed no significant fluctuations from their average radon-in-water activity concentration, with standard deviations of ~20% at a coverage factor of k=1. Even though some places supplied from three to four boreholes showed no significant fluctuations (standard deviation <= 30% at k=1) from their average radon level, special attention is needed for places supplied from many boreholes when one measurement over the year is to be performed for the annual effective dose assessment. This is because the prevailing during-year borehole combination may not exist on the measurement day, resulting in an underestimated or overestimated dose assessment. Radon removal from domestic water supplies in the Arnea village (due to elevated radon-in-water activity concentrations) did not affect the inhalation risk for the residents of an examined house in Arnea. However, radon removal from the water supply was essential to reduce the ingestion risk for the house occupants. There is a possibility of radiation overexposure (>20mSv y-1) for the workers in a thermal spa on Ikaria Island, and further investigation needs to be conducted with extended measurement periods.

Analysis of radon concentrations in drinking water in coastal regions of Karnataka, South India.

The measurements of radon activity in water samples from several parts of Karnataka were studied. Drinking water quality is a routine tool in health and environmental research. Radon exposure puts the entire public at risk for radiological damage through inhalation and ingestion. Radon concentrations were measured using the emanometry technique. Estimated 222Rn activity concentration in water has been found to vary from 2.05 to 28.02Bql-1 with an average value of 7.38Bql-1. For all samples under study, the total average annual effective doses are much less than the safe limit of 100μSv y-1.

Production of Kaeng Liang Soup (Thai Style Spicy Mixed Vegetable Soup) Powder Using Foam-mat Drying

Kaeng Liang is an ancient local Thai soup that has been reported to have many benefits along with the popularity of powdered food seasonings having increased significantly in Thailand. The aim of this study was to investigate the factors affecting the foam-mat drying of Kaeng Liang soup powder. The physical, chemical, microbiological, nutritional, and sensory properties of the sample were studied. Three Kaeng Liang soup recipes were selected to study sensory acceptability. The best formula was selected to produce Kaeng Liang soup powder by foam-mat drying. Then, the optimum level of egg white protein (EWP) at three levels namely 2%, 4%, and 6% for use in foam-mat drying was studied. The best level condition of egg white power was selected to study drying at 60°C, 70°C, and 80°C further. It was shown that using 6% EWP and drying at a temperature of 80°C for 480 min meant that the water activity content was in accordance with the standards set forth in the instant community product standards, including the water solubility index and water reabsorption index. Moreover, the microbiological qualities are in accordance with the community product standards. As for the nutritional value of Kaeng Liang soup powder, it contains carbohydrates, proteins, fats, phosphorus, and calcium respectively. The acceptance of the product by 100 consumers was established by the high sensory score in the range of extremely liked as a score of 3.82-3.91 (1-dislike extremely to 5-like extremely). Therefore, the application of foam-mat drying can be used to produce Kaeng Liang soup powder.

Investigation of environmental radioactivity levels and human health risk around San'ao Nuclear Power Plant (China) before operation

Baseline study on environmental radioactivity levels and public health conditions are crucial before the operation of nuclear facilities. Our goal is to establish a baseline database before the operation of San'ao Nuclear Power Plant (SNPP). To achieve this, water and food samples collection was carried out around the SNPP from 2021 to 2022 for laboratory analysis to determine the radioactivity levels. Thereafter, annual effective dose (AED) to local residents were evaluated by the analysis results and cancer incidence rates were analyzed by health data of local residents. Our results showed that the gross α and β activity concentrations in water varied within < 0.016–0.023 Bq/L and 0.031–0.080 Bq/L, respectively. The 90Sr and 137Cs activity concentrations range from 3.1 to 9.7 mBq/L and 0.11–0.42 mBqg/L in water, and range from 0.037 to 0.95 Bq/kg and 0.015–0.38 Bq/kg in food. All obtained results of gross α and β, 90Sr and 137Cs were below the thresholds of World Health Organization (WHO) and Chinese national standard. The AED induced by ingestion of food or drinking water were below the thresholds of WHO or Chinese national standard, indicating that radiation exposure was at a safe level. The incidence rate of all cancer sites combined among the residents around the SNPP was slightly higher than other regions, but still remained at the same scale. However, the incidence rate of thyroid cancer stood out to be significantly higher than the national average value in China, presumably due to excessive iodine intake in the study region.

Assessing radiation dosimetry for microorganisms in naturally radioactive mineral springs using GATE and Geant4-DNA Monte Carlo simulations.

Mineral springs in Massif Central, France can be characterized by higher levels of natural radioactivity in comparison to the background. The biota in these waters is constantly under radiation exposure mainly from the α-emitters of the natural decay chains, with 226Ra in sediments ranging from 21 Bq/g to 43 Bq/g and 222Rn activity concentrations in water up to 4600 Bq/L. This study couples for the first time micro- and nanodosimetric approaches to radioecology by combining GATE and Geant4-DNA to assess the dose rates and DNA damages to microorganisms living in these naturally radioactive ecosystems. It focuses on unicellular eukaryotic microalgae (diatoms) which display an exceptional abundance of teratological forms in the most radioactive mineral springs in Auvergne. Using spherical geometries for the microorganisms and based on γ-spectrometric analyses, we evaluate the impact of the external exposure to 1000 Bq/L 222Rn dissolved in the water and 30 Bq/g 226Ra in the sediments. Our results show that the external dose rates for diatoms are significant (9.7 μGy/h) and comparable to the threshold (10 μGy/h) for the protection of the ecosystems suggested by the literature. In a first attempt of simulating the radiation induced DNA damage on this species, the rate of DNA Double Strand Breaks per day is estimated to 1.11E-04. Our study confirms the significant mutational pressure from natural radioactivity to which microbial biodiversity has been exposed since Earth origin in hydrothermal springs.

Time variation of radon in tap water in locations of a Greek area with geological background for elevated radon-in-water concentrations and correlation study between radon, gross alpha, uranium, and radium concentrations

Background: Radon (222Rn), a naturally occurring radioactive gas, dissolves in water, and it can be found in elevated concentrations in public water supplies when water originates from ground sources in areas rich in uranium. An area of great interest for measuring radon-in-water is the Migdonia basin in Northern Greece due to its geological background and because all of its villages are supplied with water from boreholes.&#x0D; Objectives: The main aim of this paper was to study the time variation of radon in tap water activity concentration in nine villages of the Migdonia basin supplied with water from boreholes and to determine factors that may affect it. Radon in water correlation between the source (borehole) and the consumption point (tap) was studied for some villages. Also, the correlation among radon, gross alpha, beta, uranium (238U), and radium (226Ra) activity concentration in water was studied.&#x0D; Design and methods: Water samples were collected and measured for their radon activity concentration from 66 villages in the Migdonia basin in order to find places with relatively high radon concentrations. The time variation of radon-in-water was studied for villages that showed relatively high radon concentrations for 3–4 years (2018–2022). All samples were measured for their 222Rn activity concentration using gamma-ray spectrometry. Water samples were also analyzed for their gross alpha, beta, and uranium isotopes activity concentration.&#x0D; Results and conclusions: Average radon in tap water activity concentrations measured in the area ranged from background concentrations to 185 Bq L-1. The corresponding annual effective doses from waterborne radon inhalation using both UNSCEAR and ICRP dose conversion factors ranged from 0.01 to 0.466 mSv y-1 and from 0.02 to 0.868 mSv y-1, respectively, while radon ingestion annual effective doses varied from 0.007 to 0.324 mSv y-1. Time variation of radon activity concentration in tap water for villages supplied from one borehole or a constant number of boreholes showed relatively low standard deviations (&lt;24%) at a coverage factor of k = 1. Those deviations are probably caused by the time variation of boreholes’ radon concentration and water demand changes. A significant decline in radon concentration from the source (borehole) to the consumption point (tap water) was observed. Therefore, sampling should be performed at the consumption point. However, knowing the supplying borehole concentration is useful as it determines the potential for radon in drinking water. No apparent correlation was found among radon, gross alpha, beta, uranium, and radium concentrations in water. However, in some cases, remedial actions (withdrawal of boreholes) for uranium concentration also decreased radon concentration.

RADON IN DRINKING WATER FROM ALTERNATIVE SOURCES OF WATER SUPPLY IN THE NORTH OF KOSOVO.

In this study, the results of research on radon activity concentrations in natural mineral waters, traditionally used for drinking but also for other needs, in rural and urban households in northern Kosovo are presented. Radon activity concentration in water was measured by the alpha spectrometric method with a RAD7 device. Radon activity concentrations in the 24 waters studied ranged from 1.6±0.5 to 46.3±6.3Bq l-1, with an average activity concentration of 12.4±2.0Bq l-1, which was somewhat higher than the EPA recommended maximum activity concentration, but below the WHO recommended maximum. The contribution of radon activity concentrations in water was determined in relation to the total radon activity in air and enclosed space. The estimated annual effective doses of inhalation and ingestion radon from water were 109.4±16.7 and 2.6±0.4μSv y-1, respectively.

Metrology aspects (sampling, storage, transportation, and measurement) of radon in water

Background: Radon can enter homes using water during normal household activities, and it contributes to increasing the radon concentration of the adjacent space. Because of its gaseous form, it can easily escape during one of the procedures preceding its measurement (sampling, transport, and storage) and during its measurement resulting in its underestimation, which could lead to an underestimated dose calculation.&#x0D; Objectives: This study focused on quantifying and evaluating radon losses during sampling, transporting, and storing radon in water samples. Also, in terms of measuring radon in water activity concentration, two emanometry methods were compared to the direct method of gamma-ray spectrometry.&#x0D; Design and Methods: In terms of sampling, two methods were examined and compared. Road transport effect on radon losses was studied by measuring the radon in water concentration of radon-rich samples before and after their transportation at different ambient temperatures. Different materials (PET, glass, aluminum) were examined for their radon tightness by repetitive measurements and interpolation of the recorded data. Also, the effect of ambient temperature (1 to 40°C) on radon losses was studied during the storage phase. To compare radon in water measuring methods, water from the original bottle was poured carefully into the different sample containers that each method requires and measured by each method.&#x0D; Results and Conclusions: Sampling is the factor that can cause the most significant radon losses. Radon tightness investigation of different materials showed no significant differences in their ability to preserve radon inside the container, as their fitting curves followed the literature radon decay curve. Ambient temperature (1 to 40 °C) did not appear to affect radon losses during the storage phase. Unlike the storage phase, significant radon losses were observed during road transport at ambient temperatures of 31°C and above. Therefore, measures should be taken to avoid radon losses for ambient temperatures of 31°C and above when road transport is considered (e.g., using thermally insulated boxes and cooling elements). From the comparison of the two emanometry methods with gamma-ray spectrometry, it was found that all methods provide equal results within standard uncertainties.

Simultaneous determination of gross alpha/beta activities in water by liquid scintillation counting and its applications in the environmental monitoring

Based on the standards of ISO11704-2018 and ASTM D7283-17, a method for simultaneous determination of gross alpha and gross beta activity concentrations in water by liquid scintillation counting (LSC) was established, which can be applied to various types of water samples in routine monitoring, such as drinking water, groundwater, geothermal water, seawater, and radioactive wastewater. The sample’s pH value and concentrated volume must be controlled to avoid quenching as much as possible. The validation tests show that the deviations of gross alpha and gross beta activities can satisfy quality control requirements in a wide range of activity ratios from 1:102 to 67:1. For the actual samples, the measurement results of the LSC method are in good agreement with those of the thick source method, in which the relative deviations of gross alpha and gross beta are both less than 15% for these two methods. Moreover, the LSC method performs better in detection limit and has a simpler pretreatment process than the thick source method.

Best practices for predictions of radionuclide activity concentrations and total absorbed dose rates to freshwater organisms exposed to uranium mining/milling

Predictions of radionuclide dose rates to freshwater organisms can be used to evaluate the radiological environmental impacts of releases from uranium mining and milling projects. These predictions help inform decisions on the implementation of mitigation measures. The objective of this study was to identify how dose rate modelling could be improved to reduce uncertainty in predictions to non-human biota. For this purpose, we modelled the activity concentrations of 210Pb, 210Po, 226Ra, 230Th, and 238U downstream of uranium mines and mills in northern Saskatchewan, Canada, together with associated weighted absorbed dose rates for a freshwater food chain using measured activity concentrations in water and sediments. Differences in predictions of radionuclide activity concentrations occurred mainly from the different default partition coefficient and concentration ratio values from one model to another and including all or only some 238U decay daughters in the dose rate assessments. Consequently, we recommend a standardized best-practice approach to calculate weighted absorbed dose rates to freshwater biota whether a facility is at the planning, operating or decommissioned stage. At the initial planning stage, the best-practice approach recommend using conservative site-specific baseline activity concentrations in water, sediments and organisms and predict conservative incremental activity concentrations in these media by selecting concentration ratios based on species similarity and similar water quality conditions to reduce the uncertainty in dose rate calculations. At the operating and decommissioned stages, the best-practice approach recommends relying on measured activity concentrations in water, sediment, fish tissue and whole-body of small organisms to further reduce uncertainty in dose rate estimates. This approach would allow for more realistic but still conservative dose assessments when evaluating impacts from uranium mining projects and making decision on adequate controls of releases.

PHYSICOCHEMICAL AND SENSORY CHARACTERISTIC OF STARFRUIT-RED GUAVA FRUIT LEATHER AS AFFECTED BY THE ADDITION OF ARABIC GUM

Fruit leather is one of the processed fruit products. It’s shaped similar to thin sheets that can be rolled, has an elastic texture, and has a specific flavour. One of the suitable fruit that can be processed to fruit leather is starfruit and guava. The aim of this research was to study the physicochemical and sensory characteristics of the fruit leather made from starfruit (Dewa variety) and guava which were added with Arabic gum with different concentration (0%, 0.5%, 1%, 2%, and 2.5%). Data were analyzed by analysis of variance (ANOVA) at α = 0.05. The result showed that the addition of Arabic gum had a significant effect on tensile strength, water, ash, vitamin C content, and pH value, but it did not has a significant effect on crude fiber, water activity content, total bacteria, and total yeast and mold. While the addition of Arabic gum had a significant effect on color and texture sensory test. The best fruit leather was determined based on the physicochemical and sensory test, and it showed that the addition of 0.5% Arabic gum was the best. Characteristics of the best starfruit and guava fruit leather were tensile strength value 437.38 gf, water content 7.38%, ash content 2.02%, vitamin C content 77.08%, crude fiber content 1.85%, pH value 4.22, water activity value 0.48 , total bacteria &lt; 2.5 CFU/g, total yeast and mold &lt; 1 CFU/g with golden yellow color, slightly strong starfruit aroma, strong starfruit flavor, and elastic fruit leather texture.

ОЦЕНКА РАДИАЦИОННОЙ ОБСТАНОВКИ В РАЙОНЕ ПРОВЕДЕНИЯ МИРНОГО ЯДЕРНОГО ВЗРЫВА «ТАХТА-КУГУЛЬТА»

Purpose: Radiation survey in the area of peaceful nuclear explosion «Takhta-Kagylta» in the Stavropol Region.&#x0D; Material and methods: Radiation survey was performed on the territory of the protected area and on the territory of the 30-km zone from the explosion site. Methods of pedestrian gamma survey with a portable spectrometric complex Multirad-M were used in the course of the survey, along with gamma spectrometric and radiochemical measurements of radionuclide activities in samples and radiochemical separation of 90Sr and 137Cs. The measurement of tritium activity concentration in water was carried out using a low-background liquid alpha-beta radiometer Quantulus-1220.&#x0D; Results: The highest average value of gamma ambient dose equivalent rate was obtained in the area of the peaceful nuclear explosion site. A value of ambient dose equivalent rate at the area between the site and Kevsala village is lower than on the site, but higher than in Kevsala village and in other settlements. The mean value of the surface contamination of soil with 137Cs on the site was 0.43 kBq/m2, while that of 90Sr was 0.055 kBq/m2. Average values of soil surface contamination with radionuclides in the settlements located in the area of the explosion vary over the range between 0.16 and 0.37 kBq/m2 for 137Cs and between 0.035 and 0.066 kBq/m2 for 90Sr. 241Am specific activity values were below the minimum detectable activity (0.01 – 0.04 kBq/m2 at the time of the soil sample measurement of 10–30 h).&#x0D; The contents of 3H, 90Sr and 137Cs radionuclides in drinking water and water of the surface water reservoirs is significantly lower than the intervention levels established in NRB-99/2009. &#x0D; Conclusions: Radiation situation at the location of the technological well complies with the requirements of SanPiN 2.6.1.2819-10 “Radiation Safety and Protection of the Population Living in the Areas of Peaceful Nuclear Explosions (1965 – 1988)”, and does not pose a threat to the health of the population when staying there. It is necessary to arrange the territory of the protection area and technological (charging) well in accordance with the requirements of SanPiN 2.6.1.2819–10.&#x0D; Within the framework of long-term radiation monitoring, it is necessary to provide for the monitoring of the tritium content in the produced gas and in the groundwater of the Krasnogvardeiskoe deposit (located in the direction of the spread of groundwater from the location of the peaceful nuclear explosion).

Dosimetry of radon progeny deposited on skin in air and thermal water.

It is held that the skin dose from radon progeny is not negligibly small and that introducing cancer is a possible consequence under normal circumstances as there are a number of uncertainties in terms of related parameters such as activity concentrations in air and water, target cells in skin, skin covering materials, and deposition velocities. An interesting proposal has emerged in that skin exposure to natural radon-rich thermal water as part of balneotherapy can produce an immune response to induce beneficial health effects. The goal of this study was to obtain generic dose coefficients with a focus on the radon progeny deposited on the skin in air or water in relation to risk or treatment assessments. We thus first estimated the skin deposition velocities of radon progeny in air and thermal water based on data from the latest human studies. Skin dosimetry was then performed under different assumptions regarding alpha-emitting source position and target cell (i.e. basal cells or Langerhans cells). Furthermore, the impact of the radon progeny deposition on effective doses from all exposure pathways relating to ‘radon exposure’ was assessed using various possible scenarios. It was found that in both exposure media, effective doses from radon progeny inhalation are one to four orders of magnitude higher than those from the other pathways. In addition, absorbed doses on the skin can be the highest among all pathways when the radon activity concentrations in water are two or more orders of magnitude higher than those in air.

Composição centesimal e intenção de compra de biscoitos obtidos pela mistura das farinhas de talos de beterraba, flocos de aveia e farinha de trigo

Biscoitos tipo cookies são amplamente consumidos por pessoas de todas as faixas etárias, no entanto geralmente são elaborados a partir de farinhas refinadas. Pensando em melhorar as características nutricionais do biscoito, o objetivo deste estudo foi desenvolver um cookie a base de farinha mista de talos de beterraba (FTB) e flocos de aveia (FA) em associação com a farinha de trigo (FT). Os cookies foram desenvolvidos empregando-se o delineamento experimental centróide simplex, com um ponto central e restrição do limite máximo de farinha de trigo em 50%. Nos biscoitos foi determinada a composição centesimal e intenção de compra. A influência da mistura sobre as variáveis umidade, fibra total, fibra insolúvel, fibra solúvel, cinzas, carboidratos e intenção de compra foi explicada pelo modelo linear, já o modelo quadrático mostrou-se mais adequado para justificar o efeito das farinhas sobre o teor de proteico dos biscoitos. Os modelos propostos não conseguiram explicar a influência sobre o teor de lipídeo dos biscoitos. A FTB esteve associada a biscoitos com maiores teores de umidade, fibras, cinzas e atividade de água, apresentando efeito antagônico sobre o teor de carboidratos e sobre a aceitação. Já os FA apresentaram efeito sinérgico sobre o teor de proteína dos biscoitos. Portanto a associação de FTB e FA mostrou-se promissora para melhorar a qualidade nutricional dos biscoitos. No entanto, ressalta-se que a FTB não deve exceder 17% da base farinácea para não interferir na aceitação do produto.

Distribution and transfer of naturally occurring radionuclides and 137Cs in the freshwater system of the Plitvice Lakes, Croatia, and related dose assessment to wildlife by ERICA Tool.

The aim of this study was to investigate the natural radioactivity of Plitvice Lakes, under the assumption that due to its status as a National Park, the area can be considered an example of a natural freshwater system. Also, considering the transfer parameter data as the largest source of uncertainty in radiological risk assessments, the impact of site-specific data on dose rate assessment, as opposed to currently available data, was investigated. The study included gamma and alpha spectrometric measurements of 238U, 226Ra, 210Pb, 228Ra, and 40K in water, sediment, and fish samples, as well as 137Cs due to the coinciding of the study with the Fukushima accident. The content of naturally occurring radionuclides significantly varied in sediments of different Lakes, probably as a reflection of the different underlying geology of the area. Also, the 210Pb distribution in sediments indicated an up to 312 Bq kg-1 of the allochthonous contribution of this radionuclide at the beginning of the Lake's watercourse, which probably entered into the lake system by the major inlet river with its steady decrease along downstream lakes. Low 40K activity concentrations (27.5 ± 20.1 mBq L-1) in the Lake's waters might be one of the causes of increased 137Cs activity concentrations in fish samples (1.5 ± 0.4 Bq kg-1), which was found to be an order of magnitude higher than average values for different fish species from other Croatian freshwater systems (0.2 ± 0.1 Bq kg-1). A temporary increase of 137Cs activity concentrations was measured in water samples collected immediately after the Fukushima accident. Calculated site-specific sediment/water distribution coefficients and fish/water concentration ratios for radium and caesium were on average lower than generic ones found in the literature. Background dose rate assessments performed by the ERICA Tool indicated a profound impact of different input data on assessment results with water activity concentrations resulting in significantly higher dose rates (0.1-67 μGy h-1) in comparison to sediment activity concentrations (0.03-9 μGy h-1). An incremental dose rate due to 137Cs was found to be in the range of < 0.001-0.023 μGy h-1 which, in comparison to background dose rates, can be considered negligible.

Transport and Redistribution of Radiocesium in Fukushima Fallout through Rivers.

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released the most significant quantity of radiocesium into the environment since Chernobyl, and detailed measurements over the initial 5 years provide new insights into fluvial redistribution of radiocesium. We found that the high initial activity concentration of 137Cs-bearing suspended sediment in rivers was followed by a steep exponential decline (λ1) which extended to approximately 1 year after the accident, while the rate of initial decline in radiocesium activity concentration in water was an order of magnitude higher than rates measured after Chernobyl. Fluvial transport of 137Cs to the ocean from the Abukuma river totaled 12 TBq between June 2011 and August 2015 and almost all this radiocesium (96.5%) was transported in the particulate form. The primary sources of 137Cs were paddy fields, farmland, and urban areas [plaque-forming unit (PFU)], discharging 85% of the exported 137Cs from 38% of the watershed area. After 1 year, activity concentrations were lower and exhibited a more gradual secondary decline (λ2) which was associated with reduced radiocesium losses from PFU areas, while forest areas continue to represent more stable contaminant stores.

Temporal trends of &amp;lt;sup&amp;gt;137&amp;lt;/sup&amp;gt;Cs activity concentration in pond waters in the vicinity of Fukushima Dai-ichi nuclear power plant

Abstract. Closed and semi-closed water bodies, such as lakes and ponds, are important water resources in Fukushima area and they are the most sensitive environments to radioactive contamination after the Fukushima Dai-ichi nuclear power plant accident. Wakiyama et al. (2017) investigated 137Cs activity in water and bottom sediment in four ponds; Suzuuchi (SU), Funasawa (FS), Inkyozaka (IZ), and Kashiramori (KM), within 10 km zone from the FDNPP during 2015–2016. This study follows up their observation to address longer time trends of 137Cs activity concentration in pond waters and to show speciation of 137Cs in soil and bottom sediment. Mean total 137Cs activity concentration in water ranged from 2.5 to 29 Bq L−1. There was not found steady trend in the activity concentration of total and particulate 137Cs for four ponds. The concentration of dissolved 137Cs was usually low in winter during the entire observation period in all four ponds. A tendency to a decrease in the 137Cs activity concentration in suspended sediments was found for four ponds and the decreasing rate constants, including radiological decay, on SU, FS, IZ and KM were 0.33, 0.53, 0.29 and 0.25 yr−1, respectively. The results of sequential extractions of soil and bottom sediment samples showed higher proportion of bioavailable 137Cs, i.e., exchangeable and organic bound 137Cs, in bottom sediment than in the soil.

Long-term distribution and migration of 137Cs in a small lake ecosystem with organic-rich catchment: A case study of Lake Vorsee (Southern Germany)

In the shallow eutrophic Lake Vorsee with an organic-rich catchment the 137Cs activity concentration in water samples (n = 250) and different fish species (n = 631) was determined for a period of 30 years starting soon after the Chernobyl fallout. To understand the distribution and migration of 137Cs in the ecosystem of Lake Vorsee, also the 137Cs inventory in soils of the catchment area, in sediments, in suspended matter, in water plants, as well as its vertical distribution in soils and sediments were studied.The time dependency of the 137Cs activity concentration in water and fish was modelled with a compartment model (AQUASCOPE) as well as with the sum of two exponential functions. Results for effective half-lives of 137Cs in water are Teff1 = 1.2 a and Teff2 = 7.2 a; for small cyprinidae Teff1 = 0.6 a and Teff2 = 8.9 a; and for pike Teff1 = 1.4 a and Teff2 = 12.1 a. The vertical distribution of 137Cs activity concentration in soils was described by a partial differential equation (diffusion constant D = (1.05 ± 1.16) cm2⋅a−1 and convection speed v = (0.14 ± 0.07) cm⋅a−1) and its distribution in sediments by a system of two coupled partial differential equations (fixation rate f = 2.0 d−1; distribution coefficient Kdex = (543 ± 140) L⋅kg−1; sedimentation rate RS = (0.030 ± 0.010) g⋅(cm2⋅a)−1; bioturbation constant Dbio, decreasing linearly with depth with Dbioabs = (3.3 ± 1.0) cm2⋅a−1 at the surface).According to the extended AQUASCOPE model, the following fractions of the total 137Cs inventory were found in the different compartments of the lake ecosystem in 2016: 9.0⋅10−1 in soils of the catchment area, 1.0⋅10−1 in sediments, 5.5⋅10−5 in water, 1.5⋅10−5 in suspended matter, 1.3⋅10−5 in watermilfoil, and 1.6⋅10−6 in fish.

Effects of in vivo exposure to tritium: a multi-biomarker approach using the fathead minnow, Pimephales promelas

Tritium (3H) is a radioactive isotope of hydrogen. In the environment, the most common form of tritium is tritiated water (HTO). However, tritium can also be incorporated into organic molecules, forming organically bound tritium (OBT). The present study characterized the effects of tritium on the health of the fathead minnow, Pimephales promelas. Fish were exposed to a gradient of HTO (activity concentrations of 12,000, 25,000, and 180,000Bq/L) and OBT using food spiked with tritiated amino acids (OBT only, with an activity concentration of 27,000Bq/L). A combined exposure condition where fish were placed in 25,000Bq/L water and received OBT through feed was also studied. Fish were exposed for 60days, followed by a 60-day depuration period. A battery of health biomarkers were measured in fish tissues at seven time points throughout the 120days required to complete the exposure and depuration phases. HTO and OBT were also measured in fish tissues at the same time points. Results showed effects of increasing tritium activity concentrations in water after 60days of exposure. The internal dose rates of tritium, estimated from the tissue free-water tritium (TFWT) and OBT activity concentrations, reached a maximum of 0.65μGy/h, which is relatively low considering background levels. No effects were observed on survival, fish condition, and metabolic indices (gonado-, hepato-, and spleno-somatic indexes (GSI, HSI, SSI), RNA/DNA and proteins/DNA ratios). Multivariate analyses showed that several biomarkers (DNA damages, micronucleus frequency, brain acetylcholinesterase, lysosomal membrane integrity, phagocytosis activity, and reactive oxygen species production) were exclusively correlated with fish tritium internal dose rate, showing that tritium induced genotoxicity, as well as neural and immune responses. The results were compared with another study on the same fish species where fish were exposed to tritium and other contaminants in natural environments. Together with the field study, the present work provides useful data to identify biomarkers for tritium exposure and better understand modes of action of tritium on the fathead minnow.