Uranium In Plants Research Articles

Adsorption rate of uranium and thorium isotopes in soil and plants grown in a high background radiation area

ABSTRACT An important method for measuring radionuclide activity is alpha spectrometry. Ten soil samples were collected from the studied area. The activity concentrations of 238U and 234U in the collected soil samples ranged between 135 and 218 Bq kg–1 and between 117 and 183 Bq kg–1, respectively. 232Th, 230Th and 228Th activity concentrations ranged between 101 and 339, between 122 and 234 and between 106 and 385 Bq kg–1, respectively. When calculating the amount of radionuclide transport across the food chain, assessment models usually employ a transfer factor. Through root uptake, U and Th are transferred from the soil to food plants. To monitor the movement of radionuclides from the uranium series in diverse environments, it may be possible to use the ratios of uranium and thorium isotopes. Uranium mobility in soil depends on different physicochemical, organic and enzymatic factors and mechanisms. The high mobility of uranium is the main reason for the accumulation of uranium in the soil at root level and the possibility of its transfer to plants. A group of plants were selected that are grown in this area and the population relies on them mainly to meet their food needs. The concentration and transfer factor values of uranium isotopes were the highest in roots as compared with leaves and stems. Uranium in plants accumulates in roots and is then transferred to leaves. The mobility of uranium in plant tissues is constrained because it frequently adsorbs cell wall components. As a result, concentrations are frequently higher in tissues located in lower parts of the plant, with root surfaces having the highest concentrations.

Enhanced effects and mechanisms of Syngonium podophyllum-Peperomia tetraphylla co-planting on phytoremediation of low concentration uranium-bearing wastewater

To improve the remediation efficiency of plants on low concentration uranium-bearing wastewater and clarify its strengthening mechanism, Syngonium podophyllum-Peperomia tetraphylla co-planting system was established, the enhanced effects of plants interaction on uranium removal were investigated, the chemical forms, valence states, and subcellular distribution of uranium in plants were confirmed, and the mechanisms of alleviating uranium stress by plants interaction were revealed. In Syngonium podophyllum-Peperomia tetraphylla co-planting system, the total amount of ethanol-extracted uranium and deionized water-extracted uranium with higher toxicity in their roots were reduced by 10.30% and 7.17%, respectively, which reduced the toxicity of uranium to plants. Plants interaction can inhibit the reduction of U(VI) in the root of Peperomia tetraphylla, which is conducive to the transport of uranium from roots to shoots. In addition, uranium in plants mainly existed in the cell wall (54.44%–66.52%) and the soluble fraction (23.85%–32.89%). These results indicated that Syngonium podophyllum and Peperomia tetraphylla co-planting can enhance their effects of uranium removal by alleviating uranium stress with the cell wall immobilization and vacuole compartmentation, improving biomass of plants, increasing bioaccumulation factor and translocation factor of uranium.

Dominant factors influencing project quality in the radioactive minerals processing pilot plant construction

Monitoring and supervision of factors that predominantly affect the successful implementation of quality management systems on the project will improve the quality of construction that provides a safety factor in the construction of a pilot plant nuclear fuel processing, to determine those factors is the aim of this research. The separation of Uranium, Thorium, and Rare Earth Metals Pilot Plant was used as a case of the research. Adopted descriptive research design were the primary data collected using questionnaires. Data collected analysed thought multiple linear regressions that only done on factors that have correlation strong – very strong. International Standard Organisation series 9001:2015 and International Atomic Energy Agency safety standards series No. GS-R3 were used as independent variables (X), contamination level was used as dependent variable (Y) that reflected project quality. The result is there are three factors that statistically significant influencing project quality: leadership and commitment, project planning, and safety culture. Those factors influencing the achievement of construction quality of the pilot plant uranium, thorium and rare earth element i.e. 92.3%, while the remaining 7.7% (100-92.3%) is determined by other variables.

Speciation of uranium in plants upon root accumulation and root-to-shoot translocation: A XAS and TEM study

Uranium mobilization in surface waters and soils is highly dependent on its speciation. Links between U speciation and in planta mobility remain unclear, although understanding this relationship is essential in a view to properly develop efficient phytoremediation strategies. To address this question, we used X-ray absorption spectroscopy (XAS) and transmission electron microscopy (TEM) to determine U speciation and distribution in plant roots and leaves when exposed to U in the form of different chemical species. Our results indicate that U complexation with endogenous phosphate residues leads to its precipitation and fixation in plant organs, avoiding translocation from roots to leaves. We also show that complexation with a strong ligand such as citrate in exposure solution circumvents this precipitation, and enhances root-to-shoot translocation, in a U-carboxylate complex form. These results highlight correlations between U speciation in the environment and its mobility pattern in plants, which would help for phytoremediation purposes.

Uptake of Uranium by Lettuce (Lactuca sativa L.) in Natural Uranium Contaminated Soils in Order to Assess Chemical Risk for Consumers

Uranium mining activity in Cunha Baixa (Portugal) village has left a legacy of polluted soils and irrigation water. A controlled field experiment was conducted with lettuce (Lactuca sativa L.) in an agricultural area nearby the abandoned mine in order to evaluate uranium uptake and distribution in roots and leaves as well as ascertain levels of uranium intake by the local inhabitants from plant consuming. Two soils with different average uranium content (38 and 106 mg/kg) were irrigated with non-contaminated and uranium contaminated water ( 100 μg/l). A non-contaminated soil irrigated with local tap water (<1 μg/l uranium) was also used as a control. Uranium in lettuce tissues was positively correlated with soil uranium content, but non-significant differences were obtained from contaminated soils irrigated with different water quality. Uranium in plants (dry weight) growing in contaminated soils ranged from 0.95 to 6 mg/kg in roots and 0.32 to 2.6 mg/kg in leaves. Lettuce bioconcentration is more related to available uranium species in water than to its uranium concentration. Translocated uranium to lettuce leaves corresponds to 30% of the uranium uptake whatever the soil or irrigation water quality. A maximum uranium daily intake of 0.06 to 0.12 μg/kg bodyweight day was estimated for an adult assuming 30 to 60 g/day of lettuce is consumed. Although this value accounts for only 10% to 20% of the recommended Tolerable Daily Intake for ingested uranium, it still provides an additional source of the element in the local inhabitants’ diet.

Uranium speciation in plants

Summary Detailed knowledge of the nature of uranium complexes formed after the uptake by plants is an essential prerequisite to describe the migration behavior of uranium in the environment. This study focuses on the determination of uranium speciation after uptake of uranium by lupine plants. For the first time, time-resolved laser-induced fluorescence spectroscopy and X-ray absorption spectroscopy were used to determine the chemical speciation of uranium in plants. Differences were detected between the uranium speciation in the initial solution (hydroponic solution and pore water of soil) and inside the lupine plants. The oxidation state of uranium did not change and remained hexavalent after it was taken up by the lupine plants. The chemical speciation of uranium was identical in the roots, shoot axis, and leaves and was independent of the uranium speciation in the uptake solution. The results indicate that the uranium is predominantly bound as uranyl(VI) phosphate to the phosphoryl groups. Dandelions and lamb´s lettuce showed uranium speciation identical to lupine plants.

Biogeochemical investigation in south eastern Andhra Pradesh: the distribution of rare earths, thorium and uranium in plants and soils

The concentration of rare earth elements (REE), thorium and uranium were determined by inductively coupled plasma mass spectrometry (ICP−MS) in the plant species, Pterocarpus santalinus, P. marsupium and P. dalbergioides, and the soils on which they were growing. Higher concentrations of lanthanum (La), cerium (Ce) were observed in both plants and soils. Large amounts of thorium and uranium were found in the soil. In all tree species, the concentration of REEs were higher in the heartwood than the leaves. The heartwood of P. santalinus accumulated larger quantities of uranium (average concentration of 1.22 ppm) and thorium (mean value of 2.57 ppm) than the other two species.

Determination of uranium in plants from high background area by instrumental neutron activation analysis

One of the most important problems related to the high background area is that of environmental contamination. Therefore a number of local plants from Kasar in Koprubasi as referred to high background area, West Anatolia, were investigated for their uranium contents as well as for other elements by using instrumental neutron activation analysis (INAA). All of the plants except wheat samples contained levels above 0.6 ppm U which is the average background concentration of uranium in the ashed samples of living plant material. Beside the uranium, the concentrations of the other trace elements such as Ce, Ba, Cr, La, Sc, Rb, Fe, Zn, Zr, Eu, Co, Cs, Br, As, Na, K, in the plant ashes were also determined.

Uranium in plants of southern Sinai

Analyses of 220 individual plants, representing 40 different species from the southern Sinai desert have shown that the species' average uranium concentrations range from 0·05 to 4·8 p.p.m, with the large preponderance falling into the narrower range of 0·5 to 2·0 p.p.m. Uranium accumulation was observed to be independent of such variables as location, rock types, uranium content or chemistry of the waters, or the age of the plants sampled. The concentrations encountered in southern Sinai seem to be similar to the average data that are available for temperate zone plants despite the lower average concentration of uranium in the waters of such regions. Desert plants, which usually rely upon limited water sources of high mineral content are highly selective in their ion uptake, with uranium being merely one of the rejected elements.

Determination of natural uranium in biological samples using the solid state nuclear track detector method

For the solution of most of the problems which are connected to the biological and physiological role of natural uranium in plants and animal organisms about 10−14 g uranium should be determined. However most of the physico-chemical methods for the determination of natural uranium in biomaterials are time-consuming and possess considerable error. On the basis of addition and inner standard methods a version of Solid State Nuclear Track Detectors (SSNTD) method has been developed in order to determine the natural uranium in biospecimens. According to the experimental data simple relations have been obtained for the calculation of uranium concentration in biomaterial and minium uranium concentration in biosolution which can be measured by the detector used. Under irradiation of SSNTD at a thermal neutron flux of (3–5)·1015n·cm−2 the detector sensitivity is 2.30·10−9 g U/ml for glass detectors; 9.60·10−10g U/ml for the detectors made from artificial mica.

Radioecological Observations on Plants of the Lower Buller Gorge Region of New Zealand and their Significance for Biogeochemical Prospecting

The Buller Gorge uraniferous area of New Zealand has been studied by various workers (Beck, Reed & Willett 1958; Cohen, Brooks & Reeves 1967; Wodzicki 1959) to estimate its mineral potential. Biogeochemical prospecting (the chemical analysis of the plant cover to obtain evidence of mineralization in the soil and rocks beneath) was not used in these investigations. The technique has been used successfully in the United States (Cannon 1960), Soviet Union (Malyuga 1964) and various other countries. Unfortunately, this method cannot be used successfully without an initial orientation survey which involves studies of the plant-soil relationships and various other ecological factors such as pH, rainfall'and topography. The more thoroughly the ecology of an area is studied, the greater will be the dividends in the subsequent use of the biogeochemical method. This paper describes the principal ecological findings of such an orientation survey with particular reference not only to direct plant-soil relationships for uranium and radioactivity but also with reference to the use of 'pathfinders' for indirectly indicating the presence of uranium in plants or soils. The area under investigation is situated in the Lower Buller Gorge region of the South Island of New Zealand and is some 24 km east of the town of Westport. An aerial view of part of the gorge is shown in Plate 6. Bedded uranium deposits are found in a Cretaceous formation known as Hawks Crag Breccia (Williams 1965). This material comprises non-marine sandstones, siltstones, conglomerates and breccias and is divided into three main facies depending on the nature of the parent rock. The uranium is found in an arkosic formation known' as the Tiroroa