137Cs In Soil Research Articles

Relationship between the activity concentration of 137Cs in the growing shoots of Quercus serrata and soil 137Cs, exchangeable cations, and pH in Fukushima, Japan

Incorporation of radiocesium by plants via root uptake appears to be affected by some of the exchangeable cations in the soil and/or pH of the soil. However, few studies have examined the relationship between 137Cs in trees and soil properties in the area surrounding the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) after the accident in March 2011. To elucidate the relationships between the root uptake of 137Cs by deciduous broadleaved trees and soil properties, we measured the activity concentration of 137Cs in the growing shoots of coppiced konara oak (Quercus serrata) grown after the FDNPP accident and the amounts of total 137Cs; exchangeable (ex-) 137Cs, ex-K, ex-Mg, and ex-Ca; and pH (H2O) in soils collected from 34 forest stands in Fukushima between December 2016 and May 2017. Ex-137Cs showed a positive linear relationship with the activity concentration of 137Cs in the growing konara oak shoots, whereas ln-transformed ex-K, ex-Mg, ex-Ca, and pH (H2O) showed negative linear relationships with ln-transformed 137Cs activity concentrations in the growing shoots. However, only ex-137Cs and ex-K were identified as significant factors determining the activity concentration of 137Cs in konara oak according to multiple regression methods and a model selection using Akaike information criterion; ex-K had a stronger influence on the activity concentration of 137Cs in konara oak than ex-137Cs. In the present study, we demonstrated that soil ex-K negatively and non-linearly alters 137Cs activity concentration in deciduous broadleaved trees. We also noted that the relationship between 137Cs in deciduous broadleaved trees and soil ex-K in forests without K fertilization was similar to the relationships between 137Cs in other plants and ex-K in K-fertilized lands reported in previous studies of the FDNPP accident.

External Cesium-137 doses to humans from soil influenced by the Fukushima and Chernobyl nuclear power plants accidents: a comparative study

External exposure to gamma-photon irradiation from soil contamination due to nuclear power plant (NPP) accidents has significant contribution to human radiation exposure in the proximity of the NPP. Detailed absorbed doses in human organs are rarely reported in the literature. We applied the Monte Carlo Neutron Particle (MCNP) transport code to calculate and compare the absorbed doses in different human organs. The absorbed doses by gamma-photon radiation were from cesium-137 (137Cs) in soil contaminated by the two major NPP accidents. More serious and wide-spread impacts of the Chernobyl NPP accident on soil contamination in Ukraine, Belarus, Russia and countries as far as Sweden and Greece were due to the inland location, radiative plume transport pathway and high 137Cs emission strength (9 times the Fukushima emission). Based on our MCNP calculations, the largest absorbed dose was found in skin. The maximum calculated external 137Cs annual effective dose received from the Chernobyl accident was 10 times higher relative to the Fukushima accident. Our calculated effective doses at various influenced areas were comparable to those available in the literature. The calculated annual effective doses at areas near the Fukushima and Chernobyl NPPs exceeded the ICRP recommendation of 1 mSv yr−1.

Sorption–Diffusion Model of 137Cs Absorption by Bottom Deposits of Lakes in the Reconstruction of 137Cs Fallout to Water Basins

For 6 drainless lakes with average depths of ≤12 m, the fallout of 137Cs to water basins is reconstructed by using in calculation the sorption-diffusion model off radionuclide absorption by the bottom and the data of later (in years) monitoring of 137Cs. The model was used to calculate the concentration of 137Cs in water by the date of lake contamination, with the subsequent determination of the amount of 137Cs in the bulk of lake water. The manifold difference in the 137Cs fallout density to water basins (18–700 kBq/m2), time of 137Cs exposure, and dissimilar natural properties of lakes had no effect on the correction of estimating the 137Cs fallout: the calculated results agreed with the data on the content of 137Cs in coastal soils of water basins. By the dates of 137Cs monitoring in lake water (7, 16, 35 years after the contamination of a water basin) its amount in the water bulk did not exceed 0.18–6.6% of the amount fallen on the lake surface. The parameters of the 137Cs migration in the water–bottom system, the distribution (Kd) and diffusion (D) coefficient were 2000–4000 L/kg and 1.0–0.2 × 10–7 cm2/s, respectively. Silts as the main examples of the sorption properties of the water basin bottom determined for many years the contamination odd rainless lakes with 137Cs.

Continuous nitrogen fertilization retards the vertical migration of Fukushima nuclear accident-derived cesium-137 in apple orchard soil

We monitored the levels of cesium-137 (137Cs) in the soils of five orchards for six years following the Fukushima Daiichi Nuclear Power Plant accident on 11 March 2011 and found that the vertical distribution of accident-derived 137Cs varied significantly among the orchards with varying land-use and fertilizer management. Based on these results, this study evaluated how nitrogen (N) fertilizer management may have affected the vertical migration of 137Cs in the orchard soils. We selected an experimental orchard producing ‘Jonathan’ apples, where a long-term N-fertilizer trial has continued since 1973, with an N-fertilized plot (N plot; N added at 20 g m−2 y−1) and a non-fertilized plot (0 N plot). Five years after the accident, the vertical migration of accident-derived 137Cs was significantly lower in the N plot (2.3 cm) than in the 0 N plot (4.3 cm), suggesting greater 137Cs retention in the surface of the N plot. Application of a cesium bromide (133CsBr) tracer suggested that the retarded vertical migration of 137Cs in the N plot may be related to significantly lower amounts of exchangeable 133Cs and significantly higher proportions of non-exchangeable 133Cs in the upper 2 cm. We did not find any evidence of the aboveground plants contributing to more 133Cs retention in the N plot. However, greater 137Cs retention in the surface (0–2 cm) of the N plot may be due to more dissolved organic carbon (DOC), and high DOC may have contributed to deeper 137Cs migration in both the plots. Our results suggest that continuous N fertilizer application significantly retarded the migration of 137Cs by approximately one-half and resulted in less 137Cs reaching the mobile exchangeable form in the deeper root-zone layers.

Baseline radioecological data for the soil and selected bioindicator organisms in the temperate forest of Plitvice Lakes National Park, Croatia.

The aim of this study was to provide baseline radioecological data for the temperate forest ecosystem in Plitvice Lakes National Park. Emphasis was placed on the determination of naturally occurring radionuclides since there is an acknowledged lack of data for these radionuclides in non-accident conditions in wildlife, even for bioindicator organisms. Activity concentrations of 238U, 226Ra, 210Pb, 232Th, 40K, 134Cs, and 137Cs were measured by gamma spectrometry in soil and bioindicators: earthworms, conifer needles, mosses, and lichens. From the measured activity concentrations, concentration ratios were calculated to quantify the transfer of these radionuclides from soil to bioindicators. Our results show that soil activity concentrations are biased toward results from other studies conducted within the Dinaric mountain region. However, in moss and lichen samples, we measured higher activity concentrations of 226Ra and lower activity concentrations of 40K and 137Cs in comparison to similar studies. Also, we estimated lower concentration ratios for all radionuclides from soil to these organisms, except for 210Pb, in comparison to generic values. The transfer of 238U was generally low for all of the bioindicator organisms. For conifer needles, a correlation was found between activity concentrations of 226Ra and 137Cs in soil and related concentration ratios. Correlation was also found between the activity concentration of 40K in soil and transfer of 40K and 137Cs to mosses and lichens. A comparison with literature data highlighted the lack of 226Ra related concentration ratios for conifer trees and especially for earthworms. Therefore, the results of this study could supplement the sparse data currently available on radionuclide background data in similar ecosystems and related soil-to-wildlife transfer of radionuclides. Dose rate assessments, performed by the ERICA Tool, estimated that 96% of the overall exposure of wildlife in the Park area is due to the background dose rates, while 0.06μGyh-1 on average can be attributed as an incremental dose rate from 134Cs and 137Cs.

Results of the fourth combined scientific expedition for the radition monitoring in the Kurily-Kamchatka region of the Pacific ocean

This paper continues the series of publications on evaluation of the consequences of the Fukushima-1 nuclear power plant accident and the impact of the emergency radionuclide discharges on the contamination of the sea biota and coastal areas of the Far-East regions. In autumn 2019, the fourth scientific expedition of the Russian geographic society on the monitoring of the radiation situation in Kurily-Kamchatka region was performed on the training vessel «Professor Khlyustin». The expedition included 9 specialists from noncommercial organization «Polar research Fund «Polar Fund», «Russian state hydrometeorological institute», «Radium institute after V.G. Khlopin» of the State Corporation «Rosatom», «Kurchatov institute», «SaintPetersburg research institute of radiation hygiene after prof. P.V. Ramzaev» and «Marine state university after admiral G.I. Nevelsky». The aim of the fourth expedition was to evaluate the radiation situation in the Sea of Japan and Kurily-Kamchatka region after the Fukushima-1 NPP accident as a continuation of the similar marine expeditions in 2011, 2012 and 2014. The survey was performed in the water area of the sea of Japan and Okhotsk sea. The results indicate that the concentration of 137Cs and 90Sr in sea water, hydrobionts, soil, ground and sea vegetation is still on the baseline level due to the global fallouts.

Evaluation of 137Cs ageing by dynamics of 137Cs/133Cs ratio in Andosol paddy fields with/without potassium fertilizer application

The mobility of 137Cs in soil decreases with time owing to fixation by micaceous minerals. Such ageing is a critical parameter for estimating and predicting annual change in 137Cs contamination risk of agricultural products. The decrease in the exchangeable fraction of 137Cs has traditionally been used as an index of the 137Cs ageing. Under field conditions, however, exchangeable 137Cs is influenced by several environmental factors. In this study, we propose a new index to evaluate the 137Cs ageing with minimum influence of environmental factors. The ratio of the exchangeable 137Cs fraction to exchangeable fraction of 133Cs ((137Cs/133Cs)exch) eliminates the influence of environmental factors on exchangeable 137Cs. We assessed the applicability of the (137Cs/133Cs)exch index, using a four-year field study of a rice paddy in allophanic Andosol, starting 200 days after the Fukushima Dai-ichi Nuclear Power Plant accident. The influence of K fertilization was also investigated. The 137Cs and 133Cs exchangeable fractions varied together, indicating that both were similarly controlled by environmental factors. The values of (137Cs/133Cs)exch decreased with time, reflecting 137Cs fixation by the ageing. The half-time of the (137Cs/133Cs)exch decline was 6.6–17.7 years. Relative to K fertilization, the lack of K fertilization seemed to affect the 137Cs ageing in two ways: the early 137Cs fixation progressed more rapidly, probably because fewer competing K+ ions were present, and the long-term ageing process was occasionally hampered, probably by the release of reserve K from micaceous minerals. The (137Cs/133Cs)exch values were similar to the ratio of the 137Cs to 133Cs transfer factor of the rice straw. Thus, we conclude that the (137Cs/133Cs)exch index is reliable for evaluating the 137Cs ageing, decrease in 137Cs mobility caused by the diffusion into micaceous mineral interlayer, in the field.

Retention of 10Be, 137Cs and 210Pbxs in soils: Impact of physico-chemical characteristics

The 10Be, 137Cs and 210Pbxs radionuclide fallout has been used for the last several decades to quantify various soil and geomorphological processes on different time scales. However, a basic assumption of the studies relying on these radionuclides is that they have a strong affinity for soil particles and that their mobility in soil solution and losses through leaching can be neglected. Another area of the scientific literature deals with the radionuclide mobility in soils as solute. In that context, the objective of this work is to determine the pedological conditions under which this hypothesis of poor solute mobility of radionuclides is valid. To this end, meteoric 10Be, 137Cs and 210Pbxs concentrations were measured in six soil profiles representative of 5 soil types contrasted in terms of physico-chemical properties: an Andosol and a Luvisol under pasture, a Ferralsol and a Leptosol under forest and a Podzol both under forest and cultivation. The main soil properties (soil pH, organic carbon (OC) content, particle size distribution and specific extractions) were measured. The <2 µm fraction was extracted to measure radionuclide activities and undertake mineralogical analysis.Results show that meteoric 10Be is significantly leached from soils whose pHw is lower than 5, regardless of the <2 µm particle proportion and Fe oxides content. Significant 137Cs losses through leaching can generally be neglected except in sandy soils whose pHw is lower than 4.5 (Podzol). No significant 210Pbxs losses were evidenced. For the three radionuclides considered, the major part of their budget is associated with the <2 µm fraction. However, concerning the Andosol, the proportion of radionuclide budget associated with the <2 µm fraction represents <40%. With regards to the forested Podzol, two thirds of the 210Pbxs budget is associated with the litter. Well-crystallized Fe oxides, illite and interlayered clay minerals as well as allophane, imogolite and other Al-phases in the Andosol and kaolinite in highly weathered acidic soils (Ferralsol) were found to efficiently retain 10Be. Finally, litter degradation and the content of large particulate organic matter were shown to control 210Pbxs concentrations. As expected, our results highlight strong contrasts in the retention of the considered isotopes according to soil physico-chemical properties. Accordingly, their mobility and losses through solute transport should be considered when using them for quantifying solid transport and future mass transport models must be improved, in particular through the addition of a solute transfer term. Otherwise, soil redistribution might be strongly overestimated for Podzols, Ferralsols and also most probably for other acidic tropical soil types (Nitisols, Acrisols, Plinthisols).

Influence of Soil Characteristics and Land Use Type on Existing Fractions of Radioactive 137Cs in Fukushima Soils

Radioactive cesium (137Cs) in distinct soil fractions provides key information to its bioavailability, and therefore determining the effect of soil characteristics and land use types on existing fractions of 137Cs in soils is important for predicting future 137Cs mobility in Fukushima. Thus, the objective of this study was to investigate the influence of soil characteristics and land use types on sequentially extracted fractions of 137Cs in Fukushima. In this study, five coniferous forest soils, eight arable soils, and eight paddy rice soils were sampled in 2012 and 2013. The 137Cs in the soils were separated into four fractions; water-soluble, exchangeable, organic matter-bound and residual fractions. More than 90% of the soil 137Cs fraction for arable and paddy rice soils was found in the residual fraction, implying significantly reduced bioavailable 137Cs with higher fixation. In contrast, forest soils measured higher exchangeable and organic matter-bound fractions of 5%–33% and 9%–44%, respectively, implying future 137Cs mobility in the forest ecosystem. Correlation analysis showed a significant negative correlation (p &lt; 0.05) between the organic matter fraction and residual fraction in both arable and paddy rice soils. There was a significant positive correlation (p &lt; 0.05) for both exchangeable and residual fractions with cation exchange capacity (CEC), total carbon (TC) and total nitrogen (TN) values in arable soils. Organic matter content influenced both exchangeable and residual fractions. It was not clear whether organic matter played a direct role in 137Cs fixation or mobility in the agricultural soils. In paddy rice soils, the organic matter fraction showed a significant negative correlation with TC and TN values. Soil pH was significantly negatively correlated (p &lt; 0.05) with both water-soluble and residual fractions in forest soils but positively (p &lt; 0.1) with the organically bound 137Cs fraction.

Ecological half-lives of radiocesium on Izu-Oshima Island related with the Fukushima Daiichi nuclear power plant accident

Ecological half-lives of radiocesium were observed on Izu-Oshima Island, Japan, a place which experiences typhoons annually. The estimated ecological half-lives (uncertainty) based on the observations above an asphalt and a bare surface were 1.6 year (31.6%) and 1.9 year (14.4%), respectively; those of 134Cs and 137Cs in soil were 1.5 year (7.2%) and 4.0 year (5.9%), respectively. The radiation level was quickly returned to the original level compared to other locations that do not experience such typhoon activity.

Radiation monitoring of agricultural soils of the Volyn region in Ukraine.

The development of effective environmental management programs requires an appropriate assessment of the current state of the environment and contributes to anticipating future changes in the state of the environment. Obtaining such information is one of the main objectives of monitoring the environment, which is subject to anthropogenic stress, including radiological contamination. The distribution of radionuclides and their ability to migrate in ecological chains and concentration in individual parts requires special control in contaminated areas. The purpose of the study was to analyze the content of radionuclides ( 137Cs and 90Sr) in soils near the settlements of the zone of radioactive contamination of the Volyn region and their spatial differentiation. Priority is given to agricultural lands, soils, crop products, which necessitates the organization of targeted monitoring of the agro industrial complex. Radioactivity from 137Cs and 90Sr in the soil originating in the Volyn region was studied from 1996 to 2018. Radiation control was carried out on the area of 59852 ha (arable land - 38897 ha, meadows and pastures - 20955 ha). A significant part of the study area has elevated levels of radioactive contamination. The density of radionuclide contamination of agricultural soils in the settlements of the region has been determined. Density of pollution of all surveyed agricultural lands 137Cs ranges from 0.01 to 2.826 Ci/km2, and 90Sr from 0.01 to 0.048 Ci/km2. The radiological situation in the Volyn region (Ukraine) remains stable. There are slight fluctuations of 137Cs and 90Sr, which is due to changes in weather conditions, which leads to an increase or decrease in groundwater and as a consequence - the migration of radionuclides. The most polluted were the soils of administrative districts of Manevychi and Liubeshiv.

ORAL HYGIENE IN CHILDREN WITH DISTURBANCES IN TOOTH FORMATION WHO WERE AFFECTED AS A CONSEQUENCE OF THE ChNPP ACCIDENT.

evaluation of oral hygiene to enhance the prophylaxis of complications specifically of dental caries inchildren with disturbances in tooth formation (DTF) who live on radiologically contaminated territories after theChornobyl NPP (ChNPP) accident. Children aged 6-14 years (n = 1470) with DTF were the study subjects examined in 2012-2016. Among them there were (n = 528) residents of the zones III and IV of radiological contamination after theChNPP accident with 137Cs soil contamination density 1-15 Ci/km2. The effective radiation dose in them was notexceeding 1 mSv/year. The Green-Vermillion and Silness-Loe oral hygiene indices were assesses within clinicalexamination methods. The worth oral hygiene was revealed in children having got the DTF, compensated chronic diseases oforgans and systems, and in those with burdened radiation history. The Green-Vermilion and Silness-Loe indices were1.7 ± 0.51 and 1.65 ± 0.46 respectively. A significant deterioration in oral hygiene confirmed by the highest values of the Green-Vermillion index (1.7 ± 0.51; p < 0.001 - «unsatisfactory oral hygiene» criterion) and Silness-Loe index (1.65 ± 0.46; p < 0.001 -«poor oral hygiene» criterion) was found in children with DTF aged 6-14 years being residents of contaminated areasas a result of the Chernobyl accident. The revealed deterioration may be due to a set of negative factors, includingthe impact of ionizing radiation in low doses and peculiarities of social status. Results of the questioning of surveyed pediatric contingents both having got an DTF and with no defects of the hard tissues of teeth indicate aninsufficient level of knowledge and skills in hygienic care of oral cavity regardless of the area of residence.Development of a set of measures to prevent the DTF complications in children should be carried out taking intoaccount the state of oral hygiene, level of knowledge and skills in oral care, and include the use of hygiene products, namely toothpastes and anti-caries mouthwashes.

Динаміка радіоактивного забруднення зелених мохів в умовах свіжого бору у лісах Житомирського Полісся

Досліджено зміну вмісту радіонуклідів у фітомасі зелених (брієвих) мохів в умовах свіжого бору Українського Полісся впродовж 2016–2018 рр. Середня щільність радіоактивного забруднення ґрунту на пробній площі становила 199±52 кБк/м2. З'ясовано, що величини питомої активності та інтенсивності надходження радіонуклідів до фітомаси аналізованих видів мали значні коливання. Вміст радіонукліду у фітомасі дикрану багатоніжкового за період спостережень зменшився в 1,3 раза, а для плевроцію Шребера подібне зменшення становило 1,2 раза. Виявлено, що дикран багатоніжковий характеризується більшими величинами концентрації 137Cs порівняно з плевроцієм Шребера, в середньому – в 1,5 раза за досліджуваний період. Відзначено загальну закономірність щодо розподілу вмісту 137Cs за фракціями зелених мохів. За величиною радіоактивного забруднення фракції моху можна розмістити у вигляді такого ряду: очос &gt; жива фракція &gt; мертва фракція. Упродовж трьох років спостережень середній вміст 137Cs в очосі верхоплідного та бокоплідного мохів зменшився в 1,4 та 1,2 раза відповідно, а для живої та мертвої фракцій таке зменшення становило 1,3 раза. Інтенсивність надходження радіонуклідів до фітомаси плевроцію Шребера в 1,4 раза менша порівняно з дикраном багатоніжковим. Виявлено тенденцію до зниження значень коефіцієнта переходу 137Cs, як до фітомаси загалом, так і до окремих фракцій обох досліджуваних видів моху.

. Аналіз проблем та оцінка перспектив використання паливної деревини, отриманої на територіях забруднених внаслідок аварії на ЧАЕС

The Chernobyl accident led to radioactive contamination of large areas of Ukraine. The maximum number of radionuclides fell in the Ukrainian Polissya Zone. The areas of Zhytomyr, Rivne, Kyiv, Chernihiv and Volyn regions were especially polluted, with almost 40% of our country's forest areas concentrated, where significant volumes of timber harvesting occur. The forest, which is most contaminated with radioactive isotopes, grows on peat and sod-podzolic soils. These soils have varying degrees of moisture, high acidity (pH up to 3.2), low humus content, particles, exchangeable cations and clay minerals. Under these conditions, the 137 Cs and 90 Sr isotopes have high bioavailability. The research purpose is substantiating the possibility of using wood for fuel power plants from the territories of the forest that have been exposed to radioactive contamination due to the Chernobyl accident. The studies were conducted on the territory of forest areas in the northern parts of Zhytomyr (Naroditsky, Ovrutsky, Olevsky, Lugin and Malinsky areas) and Rivne regions (Sarninsky and Rokytnovsky areas). The levels of contamination of fuel wood were assessed by sampling soil and wood of the most common deciduous and coniferous tree species in these forests. At each sampling point, the GPSmap 78s (Garmin, USA) set geographic coordinates on the WGS84 and mapped them. The 137 Cs and 90 Sr activity were measured in the soil and wood samples selected. The 137 Cs content was determined using a gamma spectrometer with a semiconductor detector made of high purity germanium GEM-30185 by EG & ORTEC (USA). The content of 90 Sr in the samples was determined after its radiochemical isolation according to the activity of its 90 Y daughter radionuclide on the SEB-01 beta spectrometer (ACP, Ukraine). The specific activity of 137 Cs and 90 Sr in forest soils was 33¸675 Bq / kg and 1.5¸51 Bq / kg, respectively, which corresponds to a contamination density of 20-100 kBq / m 2 at 137 Cs and 0.2–4 kBq / m 2 at 90 Sr. Most samples showed a significant decrease in 90 Sr content relative to 137 Cs in the 20 cm layer of forest soil. On average, the content of 137 Cs in soil was 22 times the content of 90 Sr. The acidity of the soil extract varied within the pH = 4.0–7.4 and averaged pH = 6.4. The calcium content is very low and averages 0.7 mg-eq / 100 g of soil. The 137 Cs content in the wood was found to be ˂2.0 to 690 ± 83 Bq / kg. About 98% of the analyzed samples answered GNPAR-2005 with respect to 137 Cs content in the fuel wood (600 Bq / kg). The 90 Sr content in the samples ranged from 3 ± 0.3 to 473 ± 37 Bq / kg. The overdose of its acceptable level was recorded in 14.7% of samples. In the hardwood samples, the ratio of 137 Cs / 90 Sr was 1.4 ± 0.6. In conifer samples, this ratio has a wide amplitude of oscillation and averages 4.82 ± 2. According to the breed composition, the ratio 137 Cs / 90 Sr in wood is as follows: common pine˃ birch˃ oak˃ alder˃ hornbeam˃ aspen. A number of wood samples had a specific activity at 90 Sr over 100 Bq / kg. When burning this wood, the radioactivity of the ash will be ≥ 10 kBq / kg, which, according to the OSPU-2005, is radioactive waste and requires appropriate management of such ash. The analysis of the results revealed that even from radioactively contaminated forests with a contamination density of 90 Sr in the area below 4 kBq / m 2 , it is possible to obtain wood with a content of 90 Sr above the hygienic standard for fuel wood (GNPAR-2005), which requires a restriction onsite of fuel and wood from these territories. Hardwoods have been found to accumulate 90Sr much more intensively than pine. It was determined that 14.7% of wood samples with 90 Sr content and 1.1% with 137 Cs content exceed the hygienic standard for fuel and fuel wood firewood according to GNPAR-2005 (60 Bq / kg and 600 Bq / kg respectively). Contamination of the 90 Sr forest area with a density of 4 kBq / m 2 is possible to obtain wood with a content of 90 Sr above the hygienic standard for fuel and fuel beams (GNPAR-2005), which requires restrictions on the use of fuel and small wood from these territories. The specific radioactivity of the ash obtained by burning such wood exceeds 10 kBq / kg. The use of wood for radionuclide contaminated forests requires careful radiological monitoring and the introduction of appropriate permissible levels for fuel power plants.

Correlation Between \(^{137}\text{Cs}\) and \(^{40}\text{K}\) Concentration in Soil and Tea Tree in Luong My Farm, Hoa Binh Province, Vietnam

In this work, the correlation between 137Cs and 40K concentration in tea tree and soil in Luong My farm, Tan Thanh district, Luong Son commune, Hoa Binh province was experimentally investigated. The measurements were carried out using gamma spectroscopy with high purity germanium detector HPGe. The results showed that 40K is uniformly distributed in the soil depth while 137Cs is mainly located in 10 cm of the soil surface. Soil-plant transfer factor (TF) for 40K varies in the range of 0.491 to 0.623 and that of 137Cs is in range of 0.384 to 0.510. The concentration of these two radionuclides in tree parts is opposite to each other, while 40K is concentrated in the leave, 137Cs is mainly found in the root.

Could 137Cs remediation be accomplished with stable cesium (CsCl) on tropical soils?

Stable cesium can be considered as the best element for desorption of soil radio-cesium. It is considered an element that slightly absorbed by plants, so that the application of high doses to the soil could increase the absorption of 137Cs, which is desired for the remediation of contaminated soils. There is shortage of knowledge on remediation of tropical and subtropical soils contaminated with 137Cs. The aim of this work was to evaluate the use of 133Cs for the remediation of Brazilian tropical and subtropical soils contaminated with 137Cs. In addition, we investigated the Cs uptake by bean plants (Phaseolus vulgaris L.) grown in Cs contaminated soil. The experiment was carried out in pots under greenhouse conditions. Seven soil types were used in the experiment (Oxisol, Udox, Psamment, Ochrept; Aquoll; Udox and Udult), which received the application of four doses of 133Cs (0, 5, 10 and 20 mg/pot in a completely randomized design arranged in a factorial scheme (7 soil types x 4 doses of 133Cs) with three replicates. An increase in transfer factor values of 137Cs was observed for both shoot growth and grains, as well as in percentage of total activity of 137Cs removed from the soil regarding to addition of stable cesium levels in all soils. The results showed that psamment soil presented higher specific activity of 137Cs in the soil and grains, as well as for the transfer coefficient from soil to shoot growth and grains. The application of stable cesium chloride to soil did not cause any effects on dry matter production of shoot growth and grains. The addition of 133Cs increased the transfer from soil 137Cs to the plant regardless of soil type, proving the efficiency of this practice for the remediation of soils contaminated with radioactive Cs. In addition, the plants of common bean were efficient for use in phytoremediation.

Temporal distribution of Fukushima-derived 137Cs in coniferous forest soil evaluated based on compartment-exponential model

Based on the compartment and exponential models, the distribution of Fukushima-derived 137Cs was evaluated at four sampling dates in undisturbed coniferous forest soil. The compartment model was employed to evaluate the dynamic of 137Cs in the three sub-sections of the forest floor (FF), namely undergrowth (UG), litter layer (OL), and fragmented litter layer (OF), while the exponential model was administrated to describe its distribution below the FF. According to the compartment model, the derived ecological half-life of 137Cs in the UG, OL, and OF layers was 0.97, 1.1, and 4.9 years, respectively, indicating 137Cs resides much longer in the OF layer. Hence, this soil section remains a potential source of radiation dose mainly due to its high 137Cs content associated with low attenuation effect. Below the OF layer, the 137Cs distribution was well described by exponential model and its derived relaxation lengths were in the range of 0.8-1.4 cm, implying the migration of 137Cs in mineral soil is very slow and almost intact during the observation time. Collectively, our results highlighted that the compartment model for the FF and the exponential model for the soil below the FF are adequate enough to generate essential information. Thus, the potential decontamination measures should have to be chosen on their effect on the FF's 137Cs. Graphical abstract.

Effects of the dissolved organic matter on Cs transport in the weathered granite soil

It is important to understand the migration of Cesium (Cs) in soils, particularly after the nuclear power plant accident at Fukushima Dai-ichi, Japan. Dissolved organic matter (DOM) is one of factors affecting the migration of Cs in soils under flowing water conditions. We investigated the effect of DOM on the migration of Cs adsorbed to the clay planar site via laboratory column experiments. The sequence of DOM application had a significant influence on Cs transport in the soil. When DOM was applied concurrently with or prior to Cs application, the DOM adsorbed on to the clay planar site adsorbed onto the soil solid surface and enhanced Cs adsorption; consequently, it slowed Cs migration in the soil. In particular, in the case of DOM loaded prior to the application of Cs solution, a noticeable delay in Cs migration was observed. On the other hand, when DOM was applied to the soil where the Cs solution had been previously applied, the DOM desorbed Cs from the soil. DOM in liquid phase enhanced the migration of Cs through the formation of binding to organic matter. Majority of Cs affected by DOM was the exchangeable fraction that adsorbed to the clay planar site. In other words, DOM attached to the soil would adsorb Cs as a easily exchangeable form and depress migration of Cs. On the other hand, DOM in the soil solution may up take adsorbed Cs from the soil and enhanced the transport in the form of Cs bound to DOM.

Natural and anthropogenic radionuclides in urban soil around non-nuclear industries (Northern Al Jubail), Saudi Arabia: assessment of health risk.

The residential areas are located around one of the oldest and largest non-nuclear industrial cities in Saudi Arabia, Arabian Gulf. Therefore, it is important to study the radioactivity levels in the urban soil in order to estimate the potential risk of radiation in environment and for public. The activity concentrations of 226Ra, 232Th, 40K, and 137Cs in urban soil around non-nuclear industries were measured using gamma ray spectrometric technique. The mean values of activity concentrations were found to be 7.64 ± 0.4, 3.76 ± 0.2, 174 ± 3.7, and 0.391 ± 0.03 (Bq/kg) for 226Ra, 232Th, 40K, and 137Cs, respectively. Radium equivalent activity (Raeq), gamma absorbed dose rate in air (D), and annual effective dose equivalent (E) for outdoor were calculated. The mean values of these radiological parameters were found to be less than the allowed limits in soil. The obtained results were compared with other studies from Arabian Gulf and other regions of the world. Consequently, the direct gamma radiation exposure from the urban soil in the study area was found to be safe for public. Additionally, the present study is the first in this area which could be used as a baseline for radioactivity levels in soil nearby industrial areas of the Arabian Gulf region.

Vertical distribution of 137Cs in forest soil after the ground fires

We studied the influence of forest fires on vertical pattern of 137Cs specific activity concentration in forest soils. Our experiments were organized in Bazar forestry of State Enterprise (SE) “Narodychi Forestry” (Ukraine). We sampled soil in the study sites where grassfires occurred at different times, and determined the specific activity of 137Cs in all soil horizons. We determined that the forest fires and burned forest litter intensify mineralization of forest litter nutrients and increase the radionuclide content in upper layers of soil mineral part. In the following years, the radionuclides gradually move to deeper soil horizons and the difference between the burned and control areas decreases. We determined the depth of soil layer, where the changes in 137Cs specific activity occur caused by the forest fires. The time required for restoration of the original distribution is calculated. The results obtained allow us to identify a group of plants (by the location of the root system) that may have increased levels of contamination in the years following a forest fire and to determine the period when we must conduct additional radiological control of them. We suggested the recommendations on usage of non-timber forest products on the territories contaminated with radionuclides.