This study investigates redox transitions associated with the adsorption of Cr(VI) on commonly occurring soil components (silicates, oxides and humic acids) and their synthetic mixtures by coupling the mechanistic surface complexation modeling with spectroscopic and isotopic analyses. The mixtures of soil components were prepared to reflect the composition of the real anthroposol sample, determined by X-ray Powder Diffraction (XRD), total organic carbon (TOC) measurement and extraction methods. The effect of different initial Cr(VI) concentrations (2×10-2, 5×10-4, 10-4, 10-5, and 10-6M), background electrolyte (10-3, 10-2, and 10-1M KNO3), pH values (3-9), and sorbate/sorbent ratios (2g/L - 20g/L) were investigated. Maghemite and ferrihydrite were confirmed to be the main phases controlling Cr(VI) adsorption with increasing Cr(VI) concentration. Humic acids were primarily responsible for Cr(VI) reduction, especially at low pH values. The reduction of Cr(VI) was also proved in case of illite and kaolinite by XAS and isotopic analyses. Illite revealed higher reduction capacity in comparison with kaolinite based on XAS measurements. Chromium isotopic fractionation, resulting from Cr(VI) reduction, was the highest in the case of humic acids, followed by kaolinite and illite. However, a dissolution of intrinsic Cr originally present within kaolinite and illite might affect the final Cr isotopic composition of the supernatants due to its different Cr isotopic signature. In general, the combination of three different approaches was confirmed to offer more comprehensive information about Cr(VI) adsorption and/or reduction in soils. Detailed studies using soil mixtures can help to predict how the soil components affect Cr(VI) behavior in natural soils and possibly could improve the environmental remediation processes.
- Klíčová slova
- Adsorption modeling, Chromate reduction, Cr isotopes, Soil component mixtures, X-ray absorption spectroscopy,
- MeSH
- adsorpce MeSH
- chrom chemie MeSH
- látky znečišťující půdu chemie MeSH
- půda chemie MeSH
- regenerace a remediace životního prostředí * MeSH
- železité sloučeniny chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- chrom MeSH
- chromium hexavalent ion MeSH Prohlížeč
- ferric oxide MeSH Prohlížeč
- ferric oxyhydroxide MeSH Prohlížeč
- látky znečišťující půdu MeSH
- půda MeSH
- železité sloučeniny MeSH
Nano zero-valent iron (nZVI) has great potential in the remediation of metal(loid)-contaminated soils, but its efficiency in metal(loid) stabilization in the plant-microbe continuum is unclear. This study investigated nZVI-mediated metal(loid) behavior in the arbuscular mycorrhizal (AM) fungal-maize ( Zea mays L.) plant association. Plants with AM fungal inoculation were grown in metal(loid)- (mainly Zn and Pb) contaminated soils (Litavka River, Czech Republic) amended with/without 0.5% (w/w) nZVI. The results showed that nZVI decreased plant metal(loid) uptake but inhibited AM development and its function in metal(loid) stabilization in the rhizosphere. AM fungal inoculation alleviated the physiological stresses caused by nZVI and restrained nZVI efficiency in reducing plant metal(loid) uptake. Micro proton-induced X-ray emission (μ-PIXE) analysis revealed the sequestration of Zn (possibly through binding to thiols) by fungal structures in the roots and the precipitation of Pb and Cu in the mycorrhizal root rhizodermis (possibly by Fe compounds originated from nZVI). XRD analyses further indicated that Pb/Fe mineral transformations in the rhizosphere were influenced by AM and nZVI treatments. The study revealed the counteractive effects of AM and nZVI on plant metal(loid) uptake and uncovered details of metal(loid) behavior in the AM fungal-root-nZVI system, calling into question about nZVI implementation in mycorrhizospheric systems.
- MeSH
- kořeny rostlin MeSH
- látky znečišťující půdu * MeSH
- mykorhiza * MeSH
- těžké kovy * MeSH
- železo MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
- Názvy látek
- látky znečišťující půdu * MeSH
- těžké kovy * MeSH
- železo MeSH
A novel sorbent made from biochar modified with an amorphous Mn oxide (AMOchar) was compared with pure biochar, pure AMO, AMO+biochar mixtures and biochar+birnessite composite for the removal of various metal(loid)s from aqueous solutions using adsorption and solid-state analyses. In comparison with the pristine biochar, both Mn oxide-biochar composites were able to remove significantly greater quantities of various metal(loid)s from the aqueous solutions, especially at a ratio 2:1 (AMO:biochar). The AMOchar proved most efficient, removing almost 99, 91 and 51% of Pb, As and Cd, respectively. Additionally, AMOchar and AMO+biochar mixture exhibited reduced Mn leaching, compared to pure AMO. Therefore, it is concluded that the synthesis of AMO and biochar is able to produce a double acting sorbent ('dorbent') of enhanced efficiency, compared with the individual deployment of their component materials.
- Klíčová slova
- Biochar, Metals, Arsenic, Composite, Mn oxide,
- Publikační typ
- časopisecké články MeSH
Several efficient stabilizing amendments have been recently proposed for the remediation of metal(loid)-contaminated soils. However, information on their interactions with plants, which is a crucial factor in soil environments, are still scarce. An amorphous manganese oxide (AMO) synthesized from organic compounds and nano zerovalent iron (nZVI) have been previously tested as promising stabilizing agents usable both for the stabilization of metals and As. Experiments with rhizoboxes were performed in order to evaluate their influence on the mobility of metal(loid)s in the bulk soil and rhizosphere of sunflower (Helianthus annuus L.) together with their impact on metal uptake and biomass yield. Generally, AMO proved more efficient than nZVI in all stages of experiment. Furthermore, the AMO effectively reduced water- and 0.01 M CaCl2-extractable fractions of Cd, Pb and Zn. The decreased bioavailability of contaminating metal(loid)s resulted in significant increase of microbial activity in AMO-amended soil. Together with metal(loid) extractability, the AMO was also able to significantly reduce the uptake of metals and ameliorate plant growth, especially in the case of Zn, since this metal was taken up in excessive amounts from the control soil causing strong phytotoxicity and even death of young seedlings. On the other hand, AMO application lead to significant release of Mn that was readily taken up by plants. Resulting Mn concentrations in biomass exceeded toxicity thresholds while plants were showing emergent Mn phytotoxicity symptoms. We highlight the need of such complex studies involving plants and soil biota when evaluating the efficiency of stabilizing amendments in contaminated soils.
- Klíčová slova
- Immobilization, Manganese oxide, Nano zerovalent iron, Rhizobox, Stabilization,
- MeSH
- Bacteria účinky léků růst a vývoj MeSH
- biomasa MeSH
- Helianthus * růst a vývoj metabolismus MeSH
- látky znečišťující půdu analýza farmakokinetika toxicita MeSH
- oxidy chemická syntéza farmakokinetika farmakologie MeSH
- půda MeSH
- regenerace a remediace životního prostředí metody MeSH
- sloučeniny manganu chemická syntéza farmakokinetika farmakologie MeSH
- těžké kovy analýza farmakokinetika toxicita MeSH
- železo chemie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- látky znečišťující půdu MeSH
- manganese oxide MeSH Prohlížeč
- oxidy MeSH
- půda MeSH
- sloučeniny manganu MeSH
- těžké kovy MeSH
- železo MeSH
Nano zero-valent iron (nZVI) is currently investigated as a stabilising amendment for contaminated soils. The effect of pH (4-8) and time (48 and 192 h) on the behaviour of nZVI-treated Pb-Zn and As-contaminated soil samples was assessed. Additionally, soil leachates were subsequently used to study the direct interaction between soil solution components and nZVI particles in terms of mineralogical changes and contaminant retention. A typical U-shaped leaching trend as a function of pH was observed for Cd, Pb and Zn, while As was released predominantly under alkaline conditions. Oxidising conditions prevailed, so pH was the key controlling parameter rather than redox conditions. Generally, longer contact time resulted in increased soluble concentrations of metal(loid)s. However, the stabilisation effect of nZVI was only observed after the direct soil leachate-nZVI interactions, showing enhanced redox and sorption processes for the studied metals. A significant decrease of dissolved As concentrations was observed for both experimental soils, but with different efficiencies depending on neutralisation capacity, organic matter content or solid fractionation of As related to the origin of the soils. Scorodite (FeAsO4·2H2O) was predicted as a potential solubility-controlling mineral phase for As. Sorption of metal(loid)s onto secondary Fe- and Al-(oxyhydr)oxides (predicted to precipitate at pH > 5) represents an important scavenger mechanism. Moreover, transmission electron microscopy confirmed the retention of Zn and Pb under near-neutral and alkaline conditions by newly formed Fe oxides or aluminosilicates. This study shows that the efficiency of nZVI application strongly depends not only on soil pH-Eh conditions and contaminant type, but also on the presence of organic matter and other compounds such as Al/Fe/Mn oxyhydroxides and clay minerals.
- Klíčová slova
- Arsenic, Metals, Nano iron, Soil stabilisation, pH-stat leaching,
- MeSH
- arsen analýza chemie MeSH
- časové faktory MeSH
- jíl MeSH
- kadmium analýza chemie MeSH
- koncentrace vodíkových iontů MeSH
- látky znečišťující půdu chemie MeSH
- minerály chemie MeSH
- nanostruktury chemie MeSH
- olovo analýza chemie MeSH
- oxid hlinitý chemie MeSH
- oxidy chemie MeSH
- regenerace a remediace životního prostředí MeSH
- silikáty hliníku MeSH
- sloučeniny manganu chemie MeSH
- těžké kovy analýza chemie MeSH
- železo chemie MeSH
- zinek analýza chemie MeSH
- znečištění životního prostředí MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
- Názvy látek
- arsen MeSH
- jíl MeSH
- kadmium MeSH
- látky znečišťující půdu MeSH
- manganese oxide MeSH Prohlížeč
- minerály MeSH
- olovo MeSH
- oxid hlinitý MeSH
- oxidy MeSH
- silikáty hliníku MeSH
- sloučeniny manganu MeSH
- těžké kovy MeSH
- železo MeSH
- zinek MeSH
An amorphous Mn oxide (AMO), nanomaghemite, and nanomagnetite were used as potential amendments reducing the mobility of As in three contrasting contaminated soils differing in origin of As contamination. Adsorption experiments and XPS analyses combined with incubation batch experiments and pH-static leaching tests were used. The AMO showed excellent adsorption capacity for As(V) reaching a maximum of 1.79 mmol g(-1) at pH 7 and 8. Interestingly, the adsorption capacity in this case decreases with decreasing pH, probably as a result of AMO dissolution at lower pH values. Chemical sorption of As(V) onto AMO was further confirmed with XPS. Both Fe nano-oxides proved the highest adsorption capacity at pH 4 reaching 11 mg g(-1) of adsorbed As(V). The AMO was also the most efficient amendment for decreasing As concentrations in soil solutions during 8 weeks of incubation. Additionally, pH-static leaching tests were performed at pH 4, 5, 6, 7, and natural pH (not adjusted) and AMO again proved the highest ability to decrease As content in leachate. On the other hand, strong dissolution of this amendment at lower pH values (especially pH 4) was observed. For that reason, AMO appears as a promising stabilizing agent for As, especially in neutral, alkaline, or slightly acidic soils, where As(V) species are expected to be more mobile.
- Klíčová slova
- Adsorption, Arsenic, Immobilization, Mn oxide, Nanomaghemite, Nanomagnetite,
- MeSH
- adsorpce MeSH
- arsen analýza chemie MeSH
- kinetika MeSH
- koncentrace vodíkových iontů MeSH
- látky znečišťující půdu analýza chemie MeSH
- nanočástice chemie MeSH
- oxidy chemie MeSH
- půda chemie MeSH
- regenerace a remediace životního prostředí MeSH
- sloučeniny manganu chemie MeSH
- železité sloučeniny chemie MeSH
- znečištění životního prostředí analýza MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- arsen MeSH
- ferric oxide MeSH Prohlížeč
- látky znečišťující půdu MeSH
- manganese oxide MeSH Prohlížeč
- oxidy MeSH
- půda MeSH
- sloučeniny manganu MeSH
- železité sloučeniny MeSH
An amorphous manganese oxide (AMO) and a Pb smelter-polluted agricultural soil amended with the AMO and incubated for 2 and 6 months were subjected to a pH-static leaching procedure (pH 3-8) to verify the chemical stabilization effect on metals and metalloids. The AMO stability in pure water was pH-dependent with the highest Mn release at pH 3 (47% dissolved) and the lowest at pH 8 (0.14% dissolved). Secondary rhodochrosite (MnCO3) was formed at the AMO surfaces at pH>5. The AMO dissolved significantly less after 6 months of incubation. Sequential extraction analysis indicated that "labile" fraction of As, Pb and Sb in soil significantly decreased after AMO amendment. The pH-static experiments indicated that no effect on leaching was observed for Cd and Zn after AMO treatments, whereas the leaching of As, Cu, Pb and Sb decreased down to 20%, 35%, 7% and 11% of the control, respectively. The remediation efficiency was more pronounced under acidic conditions and the time of incubation generally led to increased retention of the targeted contaminants. The AMO was found to be a promising agent for the chemical stabilization of polluted soils.
- Klíčová slova
- Amorphous manganese oxide, Chemical stabilization, Metal(loid)s, Polluted soil, pH-static experiment,
- MeSH
- arsen chemie MeSH
- hutnictví MeSH
- koncentrace vodíkových iontů MeSH
- látky znečišťující půdu chemie MeSH
- nakládání s odpady MeSH
- oxidy chemie MeSH
- průmyslový odpad MeSH
- regenerace a remediace životního prostředí MeSH
- sloučeniny manganu chemie MeSH
- těžké kovy chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- arsen MeSH
- látky znečišťující půdu MeSH
- manganese oxide MeSH Prohlížeč
- oxidy MeSH
- průmyslový odpad MeSH
- sloučeniny manganu MeSH
- těžké kovy MeSH
The potential of three Fe- and Mn-(nano)oxides for stabilizing Cd, Cu and Pb in contaminated soils was investigated using batch and column experiments, adsorption tests and tests of soil microbial activity. A novel synthetic amorphous Mn oxide (AMO), which was recently proposed as a stabilizing amendment, proved to be the most efficient in decreasing the mobility of the studied metals compared to nano-maghemite and nano-magnetite. Its application resulted in significant decreases of exchangeable metal fractions (92%, 92% and 93% decreases of Cd, Cu and Pb concentrations, respectively). The adsorption capacity of the AMO was an order of magnitude higher than those recorded for the other amendments. It was also the most efficient treatment for reducing Cu concentrations in the soil solution. No negative effects on soil microorganisms were recorded. On the other hand, the AMO was able to dissolve soil organic matter to some extent.
- Klíčová slova
- Adsorption, Iron, Manganese, Oxide, Remediation,
- MeSH
- adsorpce MeSH
- dekontaminace MeSH
- kadmium chemie MeSH
- látky znečišťující půdu chemie MeSH
- lidé MeSH
- měď chemie MeSH
- olovo chemie MeSH
- oxidy chemie MeSH
- sloučeniny manganu chemie MeSH
- těžké kovy chemie MeSH
- znečištění životního prostředí prevence a kontrola MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
- práce podpořená grantem MeSH
- Názvy látek
- kadmium MeSH
- látky znečišťující půdu MeSH
- manganese oxide MeSH Prohlížeč
- měď MeSH
- olovo MeSH
- oxidy MeSH
- sloučeniny manganu MeSH
- těžké kovy MeSH
BACKGROUND: The effect of brain-vessel pathology on mortality in 57 consecutive PD patients was studied. METHODS: Baseline clinical, neuropsychological, ultrasonographic (US), and MR data obtained from patients who died (n = 18) during a 4-year follow-up period were compared with the data of patients who survived. RESULTS: US/MRI data displayed a more-severe vascular impairment in deceased patients. Differences were significant between both groups with respect to age, clinical and cognitive status, intima-media thickness, and resistance index (indicators of large and small vessel impairment). The sum score of white-matter hyperintensities was significantly higher among decedents. A cluster analysis displayed two clusters that differed in the two parameters (i.e. in age and in sum score). CONCLUSIONS: This study provides evidence that comorbid atherosclerosis and otherwise subclinical impairment of brain vessels may contribute to mortality in PD. The vascular pathology may act in association with other comorbidities on the terrain of progressive neurodegenerative pathology.
- MeSH
- analýza rozptylu MeSH
- ateroskleróza patologie MeSH
- biologické markery MeSH
- cévy patologie MeSH
- intimomediální šíře tepenné stěny MeSH
- lidé středního věku MeSH
- lidé MeSH
- magnetická rezonanční tomografie MeSH
- mozek patologie MeSH
- následné studie MeSH
- neuropsychologické testy MeSH
- Parkinsonova nemoc mortalita patologie psychologie MeSH
- přežití MeSH
- regresní analýza MeSH
- senioři MeSH
- shluková analýza MeSH
- věkové faktory MeSH
- Wechslerovy škály MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- biologické markery MeSH
This study evaluates the long-term behavior of metals in soils treated with ethylenediaminedisuccinate for remediation purposes. The addition of the chelant led to a significant increase of water-extractable copper, iron, aluminum contents and their uptake by poplar. Increased concentrations of the metals were present in the soil solution even after the 2 years of the experiment (up to a 30-, 170- and 270-fold increase for copper, iron and aluminum, respectively). Therefore, soils treated with chelants must be monitored not only for the targeted metal concentrations but also for major soil cations originating from chelant-induced dissolution of soil oxides.
- MeSH
- ethylendiaminy chemie MeSH
- kationty chemie MeSH
- látky znečišťující půdu analýza chemie MeSH
- listy rostlin chemie MeSH
- měď analýza chemie MeSH
- půda chemie MeSH
- regenerace a remediace životního prostředí metody MeSH
- stonky rostlin chemie MeSH
- sukcináty chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- (S,S)-ethylenediaminedisuccinate MeSH Prohlížeč
- ethylendiaminy MeSH
- kationty MeSH
- látky znečišťující půdu MeSH
- měď MeSH
- půda MeSH
- sukcináty MeSH
