Translocation Of 137Cs Research Articles

Activity of 137Cs and 40K Isotopes in Pine (Pinus sylvestris L.) and Birch (Betula pendula Roth) Stands of Different Ages in a Selected Area of Eastern Poland

Research Highlights: a forest is an ecosystem that allows for the assessment of radioactive contamination of the environment over several decades. (1) Background and Objectives: measurements of the activity of the 137Cs isotope in various elements of a forest ecosystem are one of the most important parameters in the assessment of radioisotope contamination. The translocation of 137Cs in the environment is determined by the activity of the natural 40K isotope in soil. The activities of 137Cs and 40K isotopes were assessed in two stands of Betula pendula and Pinus sylvestris, differing in age (30, 50, and 80 years old); (2) Materials and Methods: the research was conducted in one of the forest districts of eastern Poland. Wood, litter, and soil were collected for the tests from the sampling sites. The activity of 137Cs and 40K was determined using the γ-spectrometric method. Based on the activity of these isotopes in wood and soil, the values of translocation factors (TF) were determined; (3) Results: the highest activity of 137Cs was recorded in the wood of the oldest stands, the growth period of which coincided with the time period of intensive testing with nuclear weapons. With the growing age of the stand, the value of TF 137Cs increased, while the value of TF 40K was not dependent on the age of the stands. Birch wood accumulated more 137Cs and 40K isotopes than pine wood. (4) Conclusions: the results show a much greater radioactive contamination of the environment in eastern Poland during the testing with nuclear weapons than after the Chernobyl nuclear reactor explosion. The greater accumulation of radiocesium in birch wood than in pine wood predisposes this species to be more useful when assessing the radioactive contamination of the environment from the past.

Transfer of 137Cs into onion (Allium cepa L.) under conditions of hydroponic model experiment

Short-term hydroponic experiment was conducted to evaluate intensity of the 137Cs transfer from a solution with extremely high activity of the radionuclide into onion, considering different plant’s compartments (green leaves, bulbs, roots). It has been revealed that the root uptake of 137Cs was significantly discriminated, and not exceeded 0.01% of the total amount of radionuclide contained in the solution. At the same time, biometric indices of the plants – shoot height, roots elongation, phytomass inventory and structure – under conditions of 137Cs stress exposure were not significantly changed in comparison with the control. The main accumulation of 137Cs, which incorporated into onion, occurred in roots, especially in root tips, which are most actively involved in the processes of mass exchange between the plant and the external environment. The translocation of 137Cs into the shoot part, including the onion bulb and green leaves, was significantly suppressed, which allows considering the root system of onion as a biological barrier providing the rhizofiltration of the toxicant.

Uptake and translocation of radiocesium in cedar leaves following the Fukushima nuclear accident

Cryptomeria japonica trees in the area surrounding Fukushima, Japan, intercepted 137Cs present in atmospheric deposits soon after the Fukushima nuclear accident in March 2011. To study the uptake and translocation of 137Cs in C. japonica leaves, we analyzed activity concentrations of 137Cs and the concentration ratios of 137Cs to 133Cs (137Cs/133Cs) in old and new leaves of C. japonica collected from a forest on Mount Tsukuba between 9 and 15months after the accident. Both isotopes were also analyzed in throughfall, bulk precipitation and soil extracts. Water of atmospheric and soil origin were used as proxies for deciphering the absorption from leaf surfaces and root systems, respectively. Results indicate that 20–40% of foliar 137Cs existed inside the leaf, while 60–80% adhered to the leaf surface. The 137Cs/133Cs ratios inside leaves that had sprouted before the accident were considerably higher than that of the soil extract and lower than that of throughfall and bulk precipitation. Additionally, more than 80% of 137Cs in throughfall and bulk precipitation was present in the dissolved form, which is available for foliar uptake, indicating that a portion of the 137Cs inside old leaves was presumably absorbed from the leaf surface. New leaves that sprouted after the accident had similar 137Cs/133Cs ratios to that of the old leaves, suggesting that internal 137Cs was translocated from old to new leaves. For 17 species of woody plants other than C. japonica, new leaves that sprouted after the accident also contained 137Cs, and their 137Cs/133Cs ratios were equal to or higher than that of the soil extract. These results suggested that foliar uptake and further translocation of 137Cs is an important vector of contamination in various tree species during or just after radioactive fallout.

Varietal differences in growth and Cs allocation of blackgram (Vigna mungo) under water stress

Plant uptake and distribution of radioactive caesium (137Cs) was examined in an effort to determine how plant-water interactions differ between two blackgram plant varieties with different salt tolerance. Salt-tolerant U Taung-2 (BT) and the salt-sensitive variety Mutpe Khaing To (BS) were grown in pots filled with 137Cs-contaminated soil obtained from Nihonmatsu, Fukushima, Japan. The average soil 137Cs concentration was 1084Bqkg−1, and the soil type comprised sandy clay loam, where the sand: silt: clay proportion was 62:18:20. After growing for 15 days in a temperature-controlled growth chamber, plants were subjected to drought stress conditions by addition of either 10 or 20% polyethylene glycol (PEG 6000) to the soil to reduce the osmotic potential of the soil, or to field capacity conditions (0% PEG).Analysis of the growth traits and water relations revealed the different strategies employed by the two blackgram varieties under water stress conditions. No differences were observed among the two varieties under field capacity conditions. However, under both drought stress conditions (10 or 20% PEG), the reduction in total leaf area, total biomass and plant growth analysis parameters, in addition to the relative water content, were higher in BS than in BT plants. Both plant varieties exhibited lower 137Cs concentrations in the leaves, shoots and roots under drought stress conditions compared to plants subjected to field capacity conditions. Under drought stress conditions, BT plants showed uptake and translocation of 137Cs from the roots to shoots and leaves, while this activity was seriously limited in BS plants, and especially in the leaf portion of BS plants treated with 20% PEG. In BT plants, potassium moved more freely than Cs from roots to the aerial parts of the plant under water stress conditions, while this was not the case in BS plants. Examination of the hydraulic conductivity showed a positive correlation with the 137Cs concentration in leaf and stem. Our results showed that the accumulation and distribution patterns of 137Cs among part of the blackgram tissues were dependent on plant growth performance, water movement pathways, and selective absorption.

Radiocaesium Activity in Forest Soil of the Opole Anomaly Area (Polish–Czech Border Region)

The problem of radioactive contamination of soils within the area of the Opole Anomaly (Polish–Czech region border) was considered. The modes of radiocaesium (137Cs) accumulation in fungi, lichen, and plants were analyzed and their application as bioindicators for this isotope was discussed. The results were correlated to the physiochemical properties of soils. Moreover, a computer estimation of the parameters describing the translocation of 137Cs in soil was conducted and their influence on the course of the process was determined.