Spatial 137 Cs distribution in forest soil

Science of The Total Environment, 1999

Distribution of 137 Cs activity concentration has been measured in soils from 19 Hungarian counties. The levels of soil contamination in Hungary after the Chernobyl fallout are sufficient to study the vertical distribution of the 137 Cs under natural conditions. Samples were taken layer by layer on plain, grassy and uncultivated fields down to a depth of 20 cm. The results show that radiocaesium migrates very slowly in the soils investigated. The 137 Cs concentration peaks in almost all of the soils remain in the top 5 cm layer, but the distribution patterns are different. Variations in diffusion, sorption᎐desorption, and complexing processes, plant uptake and plant-and animal-originated mechanical changes result in the formation of site-specific radionuclide distribution profiles. On the basis of the experimental data a model has been developed for the long-term prediction of the 137 Cs migration. By application of an applied diffusion᎐convection model the results can be well fitted, the initial deposition can be calculated and the data can be used for the long-term prediction of the 137 Cs distribution profile.

Journal of Radioanalytical and Nuclear Chemistry, 2013

The aim of this work was to determine 137 Cs and 40 K radioactivities in soil samples taken from the Babia Góra National Park (BPN) in south Poland. The cluster analysis (CA) and principal component analysis (PCA) were used to discuss the obtained data. 10 cm thick soil cores were collected from the BPN area. Each sample was divided into three sub-samples. The samples were dried, homogenized and packed in polyethylene containers. The radioactivities of 137 Cs and 40 K were measured by means of gamma spectrometry. It was found that 137 Cs radioactivity in the whole 10 cm soil cores was in the range from 1,916 to 28,551 Bq m-2. The radioactivity of 40 K varied from 1,642 to 25,654 Bq m-2. Using CA it was possible to diverse the soils taking into account soil types. By use of the PCA method, it was chosen three factors which are appropriate to characterize researched parameters.

Digital autoradiography with imaging plates and microprobe analysis was used to study 137 Cs micro-distribution in thin sections of the podzolic sandy soil typical for the Chernobyl remote impact zone 25 years after the accident. The zone is notable for contamination of the so-called condensation type where the contribution of the "hot" fuel particles was comparatively low. The initial 137 Cs contamination level of the study plot located on the Iput river terrace ca. 20 km to the east of the town of Novozybkov, Bryansk region, was approx. 40 Ci/km 2 . According to the modern soil core data the main portion of cesium radioisotopes is still concentrated in the 10-20 cm thick surface layer. Thin sections were prepared from the top 0-10 cm layer of the soil profile located on the shoulder of the relatively steep northern slope of the forested hill. Autoradiography of the thin sections has clearly shown both cluster and dispersed patterns of 137 Cs distribution presumably reflecting initial radiocesium accumulation in the surficial organic layer with mineral admixture and subsequent lateral and vertical propagation due to water movement and filtration. The propagation was accompanied by fixation of 137 Cs ions on surfaces of soil particles. High sensitivity (0.03 Bq/cm 2 ) and resolution (ca 40 μm) of the applied technique enable us to reveal concentration and dispersion zones in soil thin sections on microscale level. Soil micromorphology and microprobe analysis have shown to be helpful in deciphering soil chemical and mineral composition assumed to be responsible for 137 Cs retention in the soil top layer.

In 2010-2012, an extensive study was performed in forest sites of Mount IDA (Kazdagi)/ Edremit 26 years after the Chernobyl accident. The 137Cs activity concentrations were determined by gamma-ray spectrometry in the forest soil layers (OL, OF þ OH and A horizons) separately. Based on 341 surface soil samples and 118 soil profiles, activity concentrations of 137Cs in OL horizons varied between 0.25 ± 0.14 and 70 ± 1 Bq kg-1, while the ranges of 137Cs activity concentrations in OF þ OH and A horizons were 13 ± 1e555 ± 3 Bq kg-1 and 2 ± 1e253 ± 2 Bq kg-1, respectively. Cesium-137 deposition in the study area was estimated to be in the range of 1e39 kBq m-2 and a linear relationship between the deposition of 137Cs and the altitude was observed. The distributions of 137Cs activities in OL, OF þ OH and A horizons throughout the region were mapped in detail. The highest 137Cs activities were found in OF þ OH horizons, with markedly lower 137Cs activity in mineral horizons of soil profiles. It is observed that 137Cs content of humus layer increases with the thickness of the humus layer for coniferous forest sites. The 137Cs activity concentrations were higher than the recommended screening limits (150 Bq kg-1) at some of the investigated areas. The current activity concentration of top soil layers indicates that over many years since the initial deposition, 137Cs activity is keeping still high in the organic horizons.

Journal of Environmental Radioactivity, 1999

The distribution of 137 Cs was studied in podzol soil profiles from a 5 year old forest clear-cut area and an adjacent mature spruce forest in central Norway in order to assess the effects of clear-cutting on the distribution and mobility of radiocaesium in surface soils. A distinctly higher radiocaesium activity observed in the humus layer from the clear-cut compared to the forest area strongly indicates an increase in organic surface soil 137 Cs activity within the first 5 years following forest clear-cutting. Such an increase, previously observed for Ca, Mg, Mn and Zn, is explained by increased supply of radiocaesium from decomposing logging residue, such as lichens and needles. Roughly 25% of the activity leached from decomposing residue had been transported into the A-E layer 5 years after clear-cutting. High 137 Cs activity in the eluvial (E) horizon and a distinct decrease in deeper horizons indicates a certain leaching of 137 Cs from the humus layer into the E horizon, which may act as an effective barrier against further leaching of radiocaesium.

Environmental Pollution, 2000

The distribution coecient of 137 Cs has been determined in 58 soils from 12 sampling points from Biscay by treating 10 g with 25 ml of an aqueous solution with an activity of 1765 Bq in the radionuclide, by shaking during 64 h and measuring the residual activity with a suitable detector. Soils were characterised by sampling depth, particle size analysis and the usual chemical parameters. Soils were thereafter treated to ®x the chemical forms of 137 Cs speciation by successive extractions in order to determine fractions due to exchangeable, associated with carbonates, iron oxide and organic matter fractions, obtaining by dierence the amount taken by the rest of the soil constituents. For this research, 16 soils from four points were selected from the previous samples. The greatest mean percentages of 137 Cs sorption were with the rest (69.93), exchangeable (13.17) and organic matter (12.54%) fractions. This paper includes also the calculation of partial distribution coecients for chemical species as well as relations of distribution coecients both among them and with soil parameters.

Journal of Geochemical Exploration, 2014

Digital autoradiography with imaging plates and microprobe analysis was used to study 137 Cs micro-distribution in thin sections of the podzolic sandy soil typical for the Chernobyl remote impact zone 25 years after the accident. The zone is notable for contamination of the so-called condensation type where the contribution of the "hot" fuel particles was comparatively low. The initial 137 Cs contamination level of the study plot located on the Iput river terrace ca. 20 km to the east of the town of Novozybkov, Bryansk region, was approx. 40 Ci/km 2 . According to the modern soil core data the main portion of cesium radioisotopes is still concentrated in the 10-20 cm thick surface layer. Thin sections were prepared from the top 0-10 cm layer of the soil profile located on the shoulder of the relatively steep northern slope of the forested hill. Autoradiography of the thin sections has clearly shown both cluster and dispersed patterns of 137 Cs distribution presumably reflecting initial radiocesium accumulation in the surficial organic layer with mineral admixture and subsequent lateral and vertical propagation due to water movement and filtration. The propagation was accompanied by fixation of 137 Cs ions on surfaces of soil particles. High sensitivity (0.03 Bq/cm 2 ) and resolution (ca 40 μm) of the applied technique enable us to reveal concentration and dispersion zones in soil thin sections on microscale level. Soil micromorphology and microprobe analysis have shown to be helpful in deciphering soil chemical and mineral composition assumed to be responsible for 137 Cs retention in the soil top layer.

Journal of Environmental Radioactivity, 2009

To give a quantitative description of the radiocaesium soil-plant transfer for fern (Dryopteris carthusiana) and blackberry (Rubus fruticosus), physical and chemical properties of soils in spruce and mixed forest stands were investigated. Of special interest was the selective sorption of radiocaesium, which was determined by measuring the Radiocaesium Interception Potential (RIP). Forest soil and plants were taken at 10 locations of the Altdorfer Wald (5 sites in spruce forest and 5 sites in mixed forest). It was found that the bioavailability of radiocaesium in spruce forest was on average seven times higher than in mixed forest. It was shown that important factors determining the bioavailability of radiocaesium in forest soil were its exchangeability and the radiocaesium interception potential (RIP) of the soil. Low potassium concentration in soil solution of forest soils favors radiocaesium soil-plant transfer. Ammonium in forest soils plays an even more important role than potassium as a mobilizer of radiocaesium. The availability factor -a function of RIP, exchangeability and cationic composition of soil solutioncharacterized reliably the soil-plant transfer in both spruce and mixed forest. For highly organic soils in coniferous forest, radiocaesium sorption at regular exchange sites should be taken into account when its bioavailability is considered.

Distribution of the 137 Cs activity concentrations, soil pH, content of organic matter and composition of mineral portion in humus were investigated in forest soils variably loaded by Chernobyl-derived fallout. Maximum in the 137 Cs activity concentrations were found in the uppermost organic soil horizons. In forest humus the 137 Cs activity concentrations was negatively related to pH and the content of organic matter. No significant content of clay minerals was detected in humus. Slow vertical migration (0.04–0.06 cm year-1) and effective half-life of 137 Cs in humus about 20 years was found. The initial surface 137 Cs activities in 1986 were estimated.

Polish Journal of Environmental Studies, 2007

This paper presents the results of determination of artificial 137 cs and natural 40 k activity concentrations and some heavy metals in soil samples from the region of one of the main valleys of Tatra national Park (Chochołowska). our investigation concentrated on 137 Cs and heavy metal levels in mountain soil taken from Chochołowska Valley, which revealed great variability in their concentration. The results show considerably small amounts of radionuclides 137 cs and 40 k in the soils. larger amounts of those elements can be found in the organic surface horizons of the soils. The evaluation of the content of those elements must be based on the bulk density analysis of the soil.