Agricultural wastes can be used as an alternative to the existing sorbents for the removal of metals or synthetic dyes from contaminated liquids. In this work, the fine powdered biomass of the hop (Humulus lupulus L.) variety Osvald's clone 72 and variety Bohemie as a sorbent for the removal of Cd from aqueous solutions of CdCl2 spiked with radionuclide 109Cd and synthetic dyes thioflavine T (ThT) or methylene blue (MB) from single dye solutions under conditions of batch systems was used. The maximum sorption capacity Q = 264 µmol Cd/g (d.w.) was found in the case of the leaf biomass of hop (H. lupulus L.) variety Osvald's clone 72 at the initial concentration of CdCl2 10,000 µmol/dm3, whereby the sorption capacity decreased in the order Qleaves : Qstems : Qroots = 1.0 : 0.8 : 0.7. The sorbed amount of Cd was removed from the hop biomass with the following increasing desorption efficiency of the extraction reagents: deionised H2O << 0.1 mol/dm3 HCl ≤ 0.1 mol/dm3 EDTA-Na2. Similarly as in the case of Cd sorption, the kinetics of ThT and MB sorption by the leaf biomass of the hop (H. lupulus L.) variety Bohemie were also showed as two-phase processes. The maximum sorption of ThT approx. Q = 19 mg/g (d.w.) and MB approx. Q = 70 mg/g (d.w.) were found within the range of the initial values of pH 4 – 7. The sorption of both dyes by the leaf biomass from single dye solutions decreased with increasing biomass concentration and on the other hand increased with increasing the initial concentrations of ThT or MB. The process of ThT and MB sorption was better described by the Langmuir model than the Freundlich model of sorption isotherm. From the obtained values of Qmax, it was found that in the case of MB the dried leaf biomass showed more than 2-times higher sorption capacity (Qmax = 184 mg/g; d.w.) in comparison with the value predicted for ThT. Obtained results suggest that dried plant biomass of hop (H. lupulus L.) as agricultural by-products can be used as a potential sorbent for both types of studied contaminants.
This work deals with sorption of cationic synthetic dye thioflavine T (ThT) onto the river sediment obtained from the Váh River under conditions of batch and column system using spectrophotometric methods. We found that sorption of ThT onto river sediment was a rapid process with reaching of concentration equilibrium within 2 h of interaction. The values of distribution coefficient (DC) defined as concentration ratio [ThT]sediment : [ThT]solution were linearly increased with increasing concentration of river sediment in solution within the range Csediment 1.25 - 10.0 g/dm3 and minimally changed in the range of initial pH values 2 - 6. The increasing concentration of ThT in model solution caused exponentially decrease in the value of DC. The sorption processes characterized by dependence between equilibrium specific sorption Qeq and ThT concentration Ceq in solution were better described by adsorption isotherm according to Freundlich (R2 = 0.979) than according to Langmuir adsorption isotherm (R2 = 0.914). From evaluation of ThT sorption onto river sediment in column system containing of 5 cm sediment layer with 30 cm of water column on the basis of ThT concentration changes in infiltrated water we found that these processes were significantly dependent on the rate of infiltrated water flow through the sediment layer Riw as well as on qualitative and quantitative composition of water. The highest ThT desorption from the sediment layer was found in seepage of 50 % (v/v) ethanol (EtOH) solution through the sediment and efficiency of ThT desorption decreased in the order: 50 % (v/v) EtOH > 0.1 mol/dm3 HCl > deionized water. Obtained data from the point of view of physico-chemical characteristics of the river sediment, such as pH, pHzpc (potentiometric titration), cation-exchange capacity (CEC) and elemental composition (X-ray fluorescence spectrometry), was also discussed
The aim of the present work was to compare the accumulation and translocation of Cd and Zn in plants of tobacco (Nicotiana tabacum L.), celery (Apium graveolens L.), maize (Zea mays L.), giant reed (Arundo donax L.), and alpine pennycress (Noccaea caerulescens L.) under conditions of short-term hydroponic experiments using nutrient solutions spiked with radionuclides 109Cd or 65Zn, and direct gamma-spectrometry. It was found that the time-course of metals accumulation in studied plants was not different in terms of target metal, but it was significantly different on the level of plant species. The highest values of Cd accumulation showed plants of giant reed, whereby the accumulation decreased in the order: giant reed > tobacco > alpine pennycress >> maize and celery. On the basis of concentration ratios (CR) [Me]shoot / [Me]root calculation for both metals, it was found that Cd and Zn were in prevailing part accumulated in the root tissues and only partially accumulated in the shoots, where the amount of accumulated Cd and Zn increased from the oldest developed leaves to the youngest developed leaves. The CR values corresponding to these facts were calculated in the range 0.06 – 0.27 for Cd and for Zn 0.06 – 0.48. In terms of plant species, the CR values obtained for Cd decreased in the order: maize > celery > tobacco and giant reed > alpine pennycress. The similarity between studied objects – individual plant species on the basis of the obtained variables defining Cd or Zn accumulation at different conditions of the experiments as well as the relationships between obtained variables and conditions of the experiments were subjected to multivariate analysis method – cluster analysis (CA). According to the findings and this analysis, it can be expected that plants of tobacco and giant reed will dispose with similar characteristics as plants of alpine pennycress, which are classified as Zn/Cd hyperaccumulators, in terms of Cd or Zn accumulation and other positive parameters for their utilization in phytoremediation processes and techniques.
A hydroponic study involving lettuce plants (Lactuca sativa L.) as a leafy vegetable was conducted to evaluate the 137Cs uptake and translocation in plant tissues in dependence on the presence or absence of K+ or/and NH4+ ions in cultivation media according to Hoagland (HM) during 8 d plants growth under hydroponic conditions. Significant increase of the 137Cs+ uptake by lettuce plants and the decrease of 137Cs+ translocation efficiency from roots to leaves were observed in 50 % HM deficient in K+ and NH4+ ions. Speciation analysis using Visual MINTEQ program showed that at micromolar concentration of CsCl (5 μmol/dm3) in 50 % HM at pH 6.0 and 25 °C, cesium was occurred practically only in the free cationic Cs+ form − 98.8 %, with minor proportions of other cesium species: CsCl − 0.4 %, CsNO3 − 0.4 %, and CsSO4 - − 0.4 %. Surplus of Cl-, NO3- and SO42- ions in HM causes the increase of proportions of the cesium species CsCl, CsNO3 and CsSO4-, respectively at the expense of bioavailable Cs+ form. Radiocesium 137Cs taken up via roots was removed from lettuce leaves with high efficiency by boiling in diluted NaCl solution. At ambient temperature the extraction of 137Cs with diluted acetic acid was concentration and time dependent process, and was succeeded by leakage of tissue components absorbing at 260 nm. These findings are important for the risk assessment of radiocesium entry into the food chain via contaminated leafy vegetable.
The aim of the present work is to characterize the soil additive derived from sewage sludge as potentially economically acceptable material for agricultural production as well as for soil and environment protection. The soil additive consisting of sewage sludge obtained from the wastewater treatment plant Pannon-Víz Zrt. (Győr, Hungary) and agricultural byproducts represented by wastes from grain mill industry and crushed corn cobs was prepared using the low-capacity granulator equipment constructed by Energy Agency Public Nonprofit Ltd. (Hungary). The characterization of sewage sludge as primary composite and prepared soil additive includes the determination of physico-chemical parameters such as pH determined in suspension with distilled water, 0.01 mol/dm3 CaCl2 or 1 mol/dm3 KCl solutions, pHzpc predicted by potentiometric titration and ProtoFit software, water holding capacity (WHC), cationexchange capacity (CEC) and total organic carbon (TOC). The elemental analysis by X-ray fluorescence spectrometry revealed that sewage sludge as well as prepared soil additive contain significant amount of Zn and Cu as important microelements in plant nutrition. Also, it was found that prepared soil additive represents the considerable source of a significant proportion, strong bound and in this way gradually released microelements. Obtained results suggest on the application potential of prepared soil additive in agricultural production as well as in remediation and reclamation of contaminated or degraded soil.
In this work, bioaccumulation and biosorption characteristics of Cd2+ ions by both dead and living non-growing biomass of gram-positive bacteria Kocuria palustris and Micrococcus luteus isolated from spent nuclear fuel pools were compared. The radioindicator method with radionuclide 109Cd was used to obtain precise and reliable data characterizing Cd compartmentalization in bacterial cells. The following cellular distribution of Cd in living non-growing biomass after 4 h incubation in solutions containing different concentration of Cd2+ ions (100, 250, 500, 750 and 1000 µmol/L) spiked with 109CdCl2 under aeration at 30 °C were obtained: in M. luteus almost 85 % of Cd was localized on the cell surface and 15 % in cytoplasm. Similarly, in K. palustris 83 % of Cd was localized on the cell surface and 17 % in cytoplasm. The data were obtained by gamma spectrometry of extracts and solids after sequential extraction of biomass with 5 mM Ca(NO3)2 and 20 mM EDTA. Biosorption of Cd by non-living bacterial biomass is a rapid process strongly affected by solution pH and as was confirmed by FTIR analysis beside carboxylate ions also other functional groups such as amino and phosphate contribute to Cd binding by bacterial cell surfaces. Maximum sorption capacities Qmax (μmol/g) calculated from the Langmuir isotherm were 444 ± 15 μmol/g for M. luteus and 381 ± 1 μmol/g for K. palustris.
Heavy metals are taken up by the vascular plant root system from water solutions in cationic forms. Subsequently, during both short and long distance transport to other plant tissues, cation forms are incorporated to many bioorganic compounds differing in stability, ionic character and physico-chemical properties such as solubility in lipid structures and mobility across cell membrane systems. Many sequential and single step extraction methods have been elaborated for characterization of the role of individual components of plant cells components in transport and detoxication of heavy metals. In our study, dry biomass of giant reed (Arundo donax L.) grown in hydroponic media spiked with 65ZnCl2 and 109CdCl2 was treated with dithizone solutions as complexing ligand in order to convert free Zn2+ and Cd2+ ions to corresponding dithizonates. Treatment with dithizone showed that up to 67 % of the total plant Cd and 56 % of the total plant Zn were transformed to dithizonate complexes extracted with chloroform. Extraction of biomass with Folch reagent showed that up to 48 % of the total root cadmium and up to 18 % of the total shoot cadmium is bound in lipid fraction. Zinc was not found in lipid fraction of root and shoot. Derivatization of the dried root and shoot lipid fraction by dithizone showed that two third of Cd in root and practically all Cd in shoot lipid fraction could be transformed to Cd-dithizonate. Methods of biomass treating with complexing ligands and a method of sequential extraction procedures with non-polar organic solvents and radiotracer methodology seem to be useful methods for the study of metal speciation and distribution in vascular plants
Application of sewage sludge to soil is a potentially inexpensive source of nutrition for plants, but may contain undesirable and toxic substances, e.g. heavy metals. Alterations in microbial communities can serve as an environmental indicator of possible soil contamination. We used two molecular fingerprinting methods (Automated Ribosomal Intergenic Spacer Analysis, ARISA and Terminal Restriction Fragment Length Polymorphism, T-RFLP) to study changes in the genetic diversity of bacterial communities in the rhizosphere of Arundo donax L. cultivated in the soil fertilised with additive based on sewage sludge from wastewater treatment plant and agricultural by-products represented by crushed corn hobs and wastes from grain mill industry. The metagenomic DNA extracted from rhizosphere samples were collected in August and November 2014. The amount of mgDNA was statistically higher in samples with additive than in control samples without it in both dates. The Venn diagrams showed that operational taxonomic units which were common to all samples were represented in 32.8% in ARISA and 43.4% in T-RFLP. However, based on Principal component analysis and subsequent PERMANOVA statistical tests did not confirm significant differences in the rhizosphere of control plants and plants grown in the soil supplemented with sewage sludge in dose 5 and 15 t/ha present in the additive.
The current findings show that positron emission tomography (PET), primarily developed for medical diagnostic imaging, can be applied in plant studies to analyze the transport and allocation of wide range of compounds labelled with positronemitting radioisotopes. This work is focused on PET analysis of the uptake and transport of 2-deoxy-2-fluoro[18F]-D-glucose (2-[18F]FDG), as a model of photoassimilates, in tissues of giant reed (Arundo donax L. var. versicolor) as a potential energy crop. The absorption of 2-[18F]FDG and its subsequent transport in plant tissues were evaluated in both acropetal and basipetal direction as well. Visualization and quantification of the uptake and transport of 2-[18F]FDG in plants immersed with the root system into a 2-[18F]FDG solution revealed a significant accumulation of 18F radioactivity in the roots. The transport rate in plants was increased in the order of plant exposure through: stem > mechanically damaged root system > intact root system. PET analysis in basipetal direction, when the plant was immersed into the 2-[18F]FDG solution with the cut area of the leaf of whole plant, showed minimal translocation of 2-[18F]FDG into the other plant parts. The PET results were verified by measuring the accumulated radioactivity of 18F by direct gamma-spectrometry.
Brown coal fly ash derived from the combustion of brown-coal in power plant ENO Nováky (Slovak Republic) was used as raw material for synthesis of zeolitic materials ZM1 and ZM3 by hydrothermal alternation with 1M NaOH and 3M NaOH, respectively. Fly ash and synthesized products were characterized using XRF and SEM-EDX analysis. Subsequently, zeolitic materials were tested as sorbents to remove Cs+ ions from aqueous solutions using radiotracer technique. Sorption of cesium by both types of zeolitic materials obeys Langmuir adsorption isotherm model. The maximum sorption capacities Qmax at pH 6.0 calculated from Langmuir isotherm were 1203 ± 65 μmol Cs+/ g for ZM1 and 1341 ± 66 μmol Cs+/ g for ZM3. The results showed that alkali treated fly ash can be used as effective sorbent for radiocesium removal from contaminated solutions