Iron-based nanomaterials have high technological impacts on various pro-environmental applications, including wastewater treatment using the co-precipitation method. The purpose of this research was to identify the changes of iron nanomaterial's structure caused by the presence of selenium, a typical water contaminant, which might affect the removal when the iron co-precipitation method is used. Therefore, we have investigated the maturation of co-precipitated nanosized ferric oxyhydroxides under alkaline conditions and their thermal transformation into hematite in the presence of selenite and selenate with high concentrations. Since the association of selenium with precipitates surfaces has been proven to be weak, the mineralogy of the system was affected insignificantly, and the goethite was identified as an only ferric phase in all treatments. However, the morphology and the crystallinity of ferric oxyhydroxides was slightly altered. Selenium affected the structural order of precipitates, especially at the initial phase of co-precipitation. Still, the crystal integrity and homogeneity increased with time almost constantly, regardless of the treatment. The thermal transformation into well crystalized hematite was more pronounced in the presence of selenite, while selenate-treated and selenium-free samples indicated the presence of highly disordered fraction. This highlights that the aftermath of selenium release does not result in destabilization of ferric phases; however, since weak interactions of selenium are dominant at alkaline conditions with goethite's surfaces, it still poses a high risk for the environment. The findings of this study should be applicable in waters affected by mining and metallurgical operations.
- MeSH
- alkálie chemie MeSH
- chemická precipitace MeSH
- krystalizace MeSH
- kyselina seleničitá chemie MeSH
- kyselina selenová chemie MeSH
- minerály chemie MeSH
- sloučeniny železa chemie MeSH
- spektroskopie infračervená s Fourierovou transformací MeSH
- spektroskopie Mossbauerova MeSH
- teplota MeSH
- železité sloučeniny chemie MeSH
- železo chemie MeSH
- Publikační typ
- časopisecké články MeSH
Natural ferric ochres that precipitate in streambeds at abandoned mining sites are natural scavengers of various metals and metalloids. Thus, their chemical and structural modification via microbial activity should be considered in evaluation of the risks emerging from probable spread of contamination at mining sites. Our results highlight the role of various aspergilli strains in this process via production of acidic metabolites that affect mobility and bioavailability of coprecipitated contaminants. The Mössbauer analysis revealed subtle structural changes of iron in ochres, while the elemental analysis of non-dissolved residues of ochres that were exposed to filamentous fungi suggest coinciding bioextraction of arsenic and antimony with extensive iron mobilisation. However, the zinc bioextraction by filamentous fungi is less likely dependent on iron leaching from ferric ochres. The strain specific bioextraction efficiency and subsequent bioaccumulation of mobilised metals resulted in distinct tolerance responses among the studied soil fungal strains. However, regardless the burden of bioextracted metal(loid)s on its activity, the Aspergillus niger strain has shown remarkable capability to decrease pH of its environment and, thus, bioextract significant and environmentally relevant amounts of potentially toxic elements from the natural ochres.
This paper investigates Aspergillus niger's behaviour in the presence of mobile Al3+ species by evaluating the changes in oxalate exudation at various aluminium contents. When the fungus was exposed to Al3+, no significant changes in oxalate production were observed until 100 mg.L-1 aluminium was reached resulting in oxalate production decrease by 18.2%. By stripping the culture medium completely of phosphate, even more prominent decrease by 34.8% and 67.1% at 10 and 100 mg.L-1 aluminium was observed, respectively, indicating the phosphate's significance instead of Al3+ in oxalate production. Our results suggest that the low phosphate bioavailability, which most likely resulted from its interaction with Al3+, stimulated the overproduction of oxalate by A. niger. Furthermore, when the fungus was incubated in aluminium-free media supplemented with 0.1 mM of phosphate, oxalate production increased up to 281.5 μmol.g-1, while at 1.85 mM of available phosphate only 80.7 μmol.g-1 of oxalate was produced. This indicates that oxalic acid is produced by fungus not as a mean to detoxify aluminium, but as an attempt to gain access to additional phosphate.
Toxicity of glyphosate (G) alone or in combination with cadmium (Cd) was studied in Matricaria chamomilla. Cadmium accumulated in shoots and roots in relation to prolonged exposure while glyphosate and aminomethylphosphonic acid (AMPA) were detected only in roots. After 7 days of exposure, root Cd and G accumulation was similar (56 μg G or 47 μg Cd/g DW in 1 μM treatments and 330 μg G or 321 μg Cd/g DW in 10 μM treatments). Despite this fact, Cd stimulated higher ROS formation and G rather suppressed nitric oxide while H2O2 content was elevated by Cd. Subsequent assay of antioxidative enzymes (SOD, CAT, and APX) showed only the impact of Cd. Non-enzymatic antioxidants revealed more pronounced impact of Cd on ascorbic acid and soluble phenols while non-protein thiols showed synergistic effect of G and Cd in roots. Surprisingly, G alone or in combination with Cd depleted shoot citrate and tartrate accumulation despite no detectable G in shoots. In the roots, Cd evoked expected increase in malate and citrate content while G rather suppressed Cd-induced elevation. These data indicate that glyphosate is less toxic than cadmium but even low G doses are able to induce metabolic changes.
Comparative accumulation of cadmium (Cd) and nickel (Ni) and the consequences for the metabolism of common weed dandelion (triploid ones of Taraxacum sect. Taraxacum) were studied here for the first time. Cd accumulated more in both shoots and roots (489 and 2486 μg/g DW) than Ni (165 and 858 μg/g DW) after 14 days of exposure and only root Ni content did not increase between 7 and 14 days of exposure. Surprisingly, though Ni was less accumulated than Cd, it had more negative impact on basic physiology (root dry biomass, shoot water content and chlorophyll amount). Ni also evoked more extensive depression of mineral nutrients (K, Ca, Mg, and Mn) in the shoots than Cd while root potassium content was elevated by both metals. Ni suppressed accumulation of total thiols but anatomical changes and ROS formation (detected by fluorescence microscopy of total ROS and lipid peroxidation) were induced more by Cd. Total soluble phenols, major (caftaric and cichoric) and minor (chlorogenic and caffeic) phenolic acids were elevated by both metals and rather increased with prolonged exposure in the shoots (14 versus 7 days). On the contrary, typically depletion of these metabolites was found in the roots after prolonged exposure to Ni, but not to Cd. Data showed distinct toxicity of Cd and Ni in dandelion. More expressive tolerance of dandelion to Cd than to Ni indicates its potential use for the remediation of Cd-contaminated environment.
- MeSH
- biodegradace MeSH
- fenoly metabolismus MeSH
- hydroxybenzoáty MeSH
- kadmium metabolismus farmakologie toxicita MeSH
- kořeny rostlin metabolismus MeSH
- nikl metabolismus farmakologie toxicita MeSH
- oxidační stres účinky léků MeSH
- peroxidace lipidů MeSH
- reaktivní formy kyslíku MeSH
- Taraxacum metabolismus MeSH
- výhonky rostlin metabolismus MeSH
- živiny MeSH
- Publikační typ
- časopisecké články MeSH
Mössbauer spectrometry is a progressive method of analysis of materials which is widely used for the study of various molecular and biomolecular systems, as well as various other objects and materials containing Mössbauer nuclides. This work is focused on applications of Mössbauer spectroscopy in the area of studying iron in biological tissues. The results of the published works show that iron in this case is present in the oxidation states Fe II and Fe III , and constitutes a part of molecules, such as ferritin, ferrihydrite, hematite, and haemosiderin. Low-temperature measurements of some types of biological tissues confirmed the presence of paramagnetic and superparamagnetic components.
The extraction and fractionation of naturally occurring iodine from environmental matrices followed by a spectrometric measurement is the most frequently used method for iodine determination. Nowadays, the inductively coupled plasma mass spectrometry (ICP-MS) represents the most common and reliable method of the total iodine content determination in environmental samples and foodstuff. Other methods such as liquid or gas chromatography which, besides iodine quantification, enable to distinguish individual iodine species are used as well. The aim of this paper is to summarize the most widely used analytical and sample preparation methods for the iodine determination in environmental matrices focused on soil and plant tissues.
Indirect impact of humic acid (HA) on metal accumulation and toxicity (Cd, Ni, Pb, and Hg; 100 μM; 24 h of exposure) in Scenedesmus quadricauda was studied. Algae were pre-cultured on solid (10 and 100 mg HA/L) or in liquid media (1, 5, and 10 mg HA/L) over 30 days and then exposed to metals mentioned above. Accumulation of applied metals irrespective of pre-culture increased in the order Ni < Cd < Pb < Hg. Algae pre-cultured on solid HA-enriched media accumulated more Cd (+ 46% at 10 mg HA/L), Ni (+ 50 and + 81% at 10 and 100 mg HA/L, respectively), and Pb (+ 15% at 100 mg HA/L) but the impact on Hg amount was not detected. Potassium and calcium decreased in response to all metals (K strongly under Hg excess) and HA had negligible impact. Interestingly, fluorescence microscopy detection of reactive oxygen species/nitric oxide (ROS/NO) balance showed that HA pre-culture suppressed ROS signal and stimulated NO signal in response to Cd (indicating positive impact of HA) while ROS signal in Ni and Pb treatments rather increased but NO signal decreased as expected from elevated Ni and Pb accumulation. Hg had clearly the most toxic impact on the ROS/NO balance. Algae pre-cultured in liquid HA-enriched media showed significantly increased Ni accumulation only (+ 14% at a dose 10 mg HA/L). Present study for the first time showed that humic acid may indirectly affect accumulation of metals and that solid HA-enriched medium used for pre-culture is more suitable to increase accumulation of metals by algae.
- MeSH
- chemické látky znečišťující vodu toxicita MeSH
- fluorescenční mikroskopie MeSH
- huminové látky analýza MeSH
- mikrořasy účinky léků MeSH
- oxidační stres MeSH
- reaktivní formy kyslíku metabolismus MeSH
- Scenedesmus účinky léků MeSH
- testy akutní toxicity MeSH
- těžké kovy toxicita MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- Publikační typ
- časopisecké články MeSH
Impact of exogenous ascorbic acid (AsA, 100μM) on acute metal toxicity (Pb and Hg, 24h of exposure to 100μM) in unicellular green alga Coccomyxa subellipsoidea was studied. Hg (often extensively) depleted amount of pigments, potassium, soluble proteins, endogenous AsA, non-protein thiols and nitric oxide signal but elevated ROS signal and activities of catalase and superoxide dismutase. Responses to Pb application (if any) were less visible with ROS signal being slightly elevated and amount of non-protein thiols being slightly reduced. Exogenous AsA considerably improved mainly Hg-induced damage at the level of oxidative stress and physiological parameters and evoked an increase in nitric oxide signal. Maximum amount of total Hg was almost 4-fold higher than that of Pb (36.5 vs. 9.73mg/g DW) and AsA depleted both total and intracellular accumulation. At the level of ascorbate-related proteins, exogenous AsA suppressed metal-induced expression and activity of MDHAR and APX but not of DHAR, which may indicate a role of DHAR in algal stress tolerance. Our data suggest that given Coccomyxa species is suitable candidate for remediation of Hg or Pb and that ascorbic acid effectively ameliorates metal-induced toxicity without side effects.
- MeSH
- antioxidancia farmakologie MeSH
- askorbátperoxidasa genetika MeSH
- chlorofyl metabolismus MeSH
- Chlorophyta účinky léků genetika metabolismus MeSH
- kyselina askorbová farmakologie MeSH
- olovo toxicita MeSH
- oxidační stres účinky léků MeSH
- oxidoreduktasy genetika MeSH
- rtuť toxicita MeSH
- superoxiddismutasa metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
The aim of this work was to optimize and validate a simple and rapid method for the direct determination of total platinum in blood serum of chemotherapy patients. The method is based on the quantification of platinum by electrothermal atomic absorption spectrometry (ET-AAS) with the Zeeman background correction after appropriate dilution of samples with 0.2% (v/v) Triton X-100 using the optimized temperature program (pyrolysis and atomization temperatures 1400 °C and 2550 °C, respectively). The validated range of quantification was 0.11–2.15 mol l1, RSD was better than 9 %. The accuracy was checked by comparing the results with those obtained by inductively coupled plasma mass spectrometry (ICP-MS). The optimized ET-AAS method is now successfully used for investigation of some pharmacokinetic parameters in a clinical study comparing intravenous and intraperitoneal infusion of carboplatin (combined with paclitaxel).
