The aim of the presented work was to evaluate the uptake and distribution of 2-fluoro-2-deoxy-d-glucose spiked with 18F (2-[18F]FDG) in tissues of tobacco plants (Nicotiana tabacum L.) by positron emission tomography and multivariate data analysis after the immersion of the petiole of excised leaf or root of a tobacco plant in a glucose solution. From individual experiments it was found that increasing glucose concentration (c glu) in the applied solution resulted in significantly higher 2-[18F]FDG diffusion and translocation within the leaf parenchyma. More than a four times increase of the 2-[18F]FDG translocation into the aboveground parts of the tobacco plant in case of the root immersion in solution with 100-times higher c glu in comparison with the control (c glu = 0.00762 mg cm−3) was determined. These facts were not confirmed only visually on basis of the obtained 3D images, but also by the increasing coincidence transfer factor (TFc) values defined by the ratio of the number of analyzed coincidences in the non-immersed parts of leaf or plant to coincidences in leaf petiole or root immersed in the solution. Cluster and principal component analysis suggest that the 2-[18F]FDG uptake by the petiole of excised leaf and root system was realized by different mechanisms; also, the 3D image quality is influenced by the initial radioactivity of the applied solution.
Sludges produced in huge amounts by wastewater treatment plants (WWTP) display high fertility properties; however, the presence of heavy metals restricts their use for agricultural purposes. Sorption capacity of sludge is generally much higher and it can also be considered as a cheap sorbent of heavy metals. The paper describes cobalt sorption by dried activated sludge (DAS) obtained from the aerobic phase of a WWTP. DAS was characterized by FT-IR spectroscopy, cation exchange capacity (CEC), and atomic absorption spectrometry (AAS) analysis. Sorption capacity of DAS (Q eq) increased with the initial concentration (C 0) of Co2+ (CoCl2) within the range from 100 μmol g−1 to 4000 μmol g−1, reaching 15 μmol g−1 and 200 μmol g−1, respectively. The maximum uptake capacity (Q max) at pH 6.0 calculated from the Langmuir isotherm model was (256 ± 9) μmol g−1 for Co2+ ions. Obtained Q values were dependent on pH within the range from 3.0 to 7.0. Competitive effect of other bivalent cations such as Ni2+ in Co2+ sorption equilibrium was confirmed; which is in agreement with the hypothesis of the decisive role of ion-exchange mechanism in metal sorption. The obtained data are discussed from the point of view of potential utilization of sludges as sorbents, i.e. in non-agricultural application.
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