Sevcu, Alena* Dotaz Zobrazit nápovědu
Nano-scale zero-valent iron (nZVI) has been conceived for cost-efficient degradation of chlorinated pollutants in soil as an alternative to e.g permeable reactive barriers or excavation. Little is however known about its efficiency in degradation of the ubiquitous environmental pollutant DDT and its secondary effects on organisms. Here, two types of nZVI (type B made using precipitation with borohydride, and type T produced by gas phase reduction of iron oxides under H2) were compared for efficiency in degradation of DDT in water and in a historically (>45 years) contaminated soil (24 mg kg(-1) DDT). Further, the ecotoxicity of soil and water was tested on plants (barley and flax), earthworms (Eisenia fetida), ostracods (Heterocypris incongruens), and bacteria (Escherichia coli). Both types of nZVI effectively degraded DDT in water, but showed lower degradation of aged DDT in soil. Both types of nZVI had negative impact on the tested organisms, with nZVI-T giving least adverse effects. Negative effects were mostly due to oxidation of nZVI, resulting in O2 consumption and excess Fe(II) in water and soil.
- MeSH
- chemické látky znečišťující vodu chemie toxicita MeSH
- DDT chemie toxicita MeSH
- ekotoxikologie MeSH
- Escherichia coli účinky léků MeSH
- ječmen (rod) účinky léků MeSH
- korýši účinky léků MeSH
- kyslík metabolismus MeSH
- látky znečišťující půdu chemie toxicita MeSH
- len účinky léků MeSH
- Oligochaeta účinky léků MeSH
- půda MeSH
- regenerace a remediace životního prostředí MeSH
- železo chemie toxicita MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Nanoremediation with iron (Fe) nanomaterials opens new doors for treating contaminated soil and groundwater, but is also accompanied by new potential risks as large quantities of engineered nanomaterials are introduced into the environment. In this study, we have assessed the ecotoxicity of four engineered Fe nanomaterials, specifically, Nano-Goethite, Trap-Ox Fe-zeolites, Carbo-Iron(®) and FerMEG12, developed within the European FP7 project NanoRem for sub-surface remediation towards a test battery consisting of eight ecotoxicity tests on bacteria (V. fisheri, E. coli), algae (P. subcapitata, Chlamydomonas sp.), crustaceans (D. magna), worms (E. fetida, L. variegatus) and plants (R. sativus, L. multiflorum). The tested materials are commercially available and include Fe oxide and nanoscale zero valent iron (nZVI), but also hybrid products with Fe loaded into a matrix. All but one material, a ball milled nZVI (FerMEG12), showed no toxicity in the test battery when tested in concentrations up to 100 mg/L, which is the cutoff for hazard labeling in chemicals regulation in Europe. However it should be noted that Fe nanomaterials proved challenging to test adequately due to their turbidity, aggregation and sedimentation behavior in aqueous media. This paper provides a number of recommendations concerning future testing of Fe nanomaterials and discusses environmental risk assessment considerations related to these.
- MeSH
- kovové nanočástice chemie toxicita MeSH
- monitorování životního prostředí metody MeSH
- regenerace a remediace životního prostředí * MeSH
- testy toxicity metody MeSH
- železo chemie toxicita MeSH
- zeolity MeSH
- znečištění životního prostředí MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Evropa MeSH
The organochlorine pesticides (OCPs) have raised concerns about being persistent and toxic to the environment. Phytoremediation techniques show promise for the revitalization of polluted soils. The current study focused on optimizing the phytoremediation potential of Miscanthus sinensis And. (M. sinensis), second-generation energy crop, by exploring two soil amendments: Tween 20 and activated carbon (AC). The results showed that when M. sinensis grew in OCP-polluted soil without amendments to it, the wide range of compounds, i.e., α-HCH, β-HCH, γ-HCH, 2.4-DDD, 4.4-DDE, 4.4-DDD, 4.4-DDT, aldrin, dieldrin, and endrin, was accumulated by the plant. The introduction of soil amendments improved the growth parameters of M. sinensis. The adding of Tween 20 enhanced the absorption and transmigration to aboveground biomass for some OCPs; i.e., for γ-HCH, the increase was by 1.2, for 4.4-DDE by 8.7 times; this effect was due to the reduction of the hydrophobicity which made pesticides more bioavailable for the plant. The adding of AC reduced OCPs absorption by plants, consequently, for γ-HCH by 2.1 times, 4.4-DDD by 20.5 times, 4.4-DDE by 1.4 times, 4.4-DDT by 8 times, α-HCH was not adsorbed at all, and decreased the translocation to the aboveground biomass: for 4.4-DDD by 31 times, 4.4-DDE by 2.8 times, and γ-HCH by 2 times; this effect was due to the decrease in the bioavailability of pesticides. Overall, the amendment of OCP-polluted soil by Tween 20 speeds the remediation process, and incorporation of AC permitted to produce the relatively clean biomass for energy.
Nanoscale zero-valent iron particles (nZVI), with sizes smaller than 100 nm, are promising for environmental remediation of polluted water, soil and sediments. nZVI particles have high potential for migration in the environment and are likely to interact not only with pollutant chemicals but also with living organisms. For these reasons, an environmental concern is rising with respect to unintended effects that need to be weighed against the benefits of remediation. The nZVI particles have a tendency to release electrons and Fe(2+). The Fe(2+) can convert less reactive hydrogen peroxide to more reactive oxygen species, particularly hydroxyl radicals, via the Fenton reaction. Hydroxyl radicals show strong biochemical activity and can react directly with membrane lipids, proteins and DNA. Reactive oxygen species are normally scavenged by antioxidants and various enzymes; however, elevated concentrations of ROS in microbial cells can result in oxidative stress. Cells under severe oxidative stress show various dysfunctions of membrane lipids, proteins and DNA. This review focuses on the processes resulting in oxidative stress and on up-to-date studies of nZVI-induced intracellular changes leading to such stress in microorganisms.
Multifunctional nanoparticles for magnetic hyperthermia which simultaneously display antibacterial properties promise to decrease bacterial infections co-localized with cancers. Current methods synthesize such particles by multi-step procedures, and systematic comparisons of antibacterial properties between coatings, as well as measurements of specific absorption rate (SAR) during magnetic hyperthermia are lacking. Here we report the novel simple method for synthesis of magnetic nanoparticles with shells of oleic acid (OA), polyethyleneimine (PEI) and polyethyleneimine-methyl cellulose (PEI-mC). We compare their antibacterial properties against single gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria as well as biofilms. Magnetite nanoparticles (MNPs) with PEI-methyl cellulose were found to be most effective against both S. aureus and E. coli with concentration for 10% growth inhibition (EC10) of <150 mg/l. All the particles have high SAR and are effective for heat-generation in alternating magnetic fields.
- MeSH
- antibakteriální látky chemie farmakologie MeSH
- biofilmy účinky léků MeSH
- Escherichia coli účinky léků fyziologie MeSH
- indukovaná hypertermie MeSH
- magnetické nanočástice chemie MeSH
- methylcelulosa chemie MeSH
- polyethylenimin chemie MeSH
- spektroskopie infračervená s Fourierovou transformací MeSH
- Staphylococcus aureus účinky léků fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Application of Fenton's reagent and enhanced reductive dechlorination are currently the most common remediation strategies resulting in removal of chlorinated ethenes. In this study, the influence of such techniques on organohalide-respiring bacteria was assessed at a site contaminated by chlorinated ethenes using a wide spectrum of molecular genetic markers, including 16S rRNA gene of the organohalide-respiring bacteria Dehaloccocoides spp., Desulfitobacterium and Dehalobacter; reductive dehalogenase genes (vcrA, bvcA) responsible for dechlorination of vinyl chloride and sulphate-reducing and denitrifying bacteria. In-situ application of hydrogen peroxide to induce a Fenton-like reaction caused an instantaneous decline in all markers below detection limit. Two weeks after application, the bvcA gene and Desulfitobacterium relative abundance increased to levels significantly higher than those prior to application. No significant decrease in the concentration of a range of chlorinated ethenes was observed due to the low hydrogen peroxide dose used. A clear increase in marker levels was also observed following in-situ application of sodium lactate, which resulted in a seven-fold increase in Desulfitobacterium and a three-fold increase in Dehaloccocoides spp. after 70 days. An increase in the vcrA gene corresponded with increase in Dehaloccocoides spp. Analysis of selected markers clearly revealed a positive response of organohalide-respiring bacteria to biostimulation and unexpectedly fast recovery after the Fenton-like reaction.
- MeSH
- Bacteria metabolismus MeSH
- bakteriální RNA genetika MeSH
- biodegradace MeSH
- chemické látky znečišťující vodu metabolismus MeSH
- chlor metabolismus MeSH
- chlorované uhlovodíky metabolismus MeSH
- genetické markery genetika MeSH
- katalýza * MeSH
- natriumlaktát aplikace a dávkování metabolismus MeSH
- oxidace-redukce MeSH
- RNA ribozomální 16S genetika MeSH
- Publikační typ
- časopisecké články MeSH
Nanoscale zero-valent iron (nZVI) is recognized as a powerful tool for the remediation of groundwater contaminated by chlorinated ethenes (CEs). This long-term field study explored nZVI-driven degradation of CEs supported by electrokinetic (EK) treatment, which positively affects nZVI longevity and migration, and its impact on indigenous bacteria. In particular, the impact of combined nZVI-EK treatment on organohalide-respiring bacteria, ethenotrophs and methanotrophs (all capable of CE degradation) was assessed using molecular genetic markers detecting Dehalococcoides spp., Desulfitobacterium spp., the reductive dehalogenase genes vcrA and bvcA and ethenotroph and methanotroph functional genes. The remediation treatment resulted in a rapid decrease of the major pollutant cis-1,2-dichloroethene (cDCE) by 75% in the affected area, followed by an increase in CE degradation products methane, ethane and ethene. The newly established geochemical conditions in the treated aquifer not only promoted growth of organohalide-respiring bacteria but also allowed for the concurrent presence of vinyl chloride- and cDCE-oxidizing methanotrophs and (especially) ethenotrophs, which proliferated preferentially in the vicinity of an anode where low levels of oxygen were produced. The nZVI treatment resulted in a temporary negative impact on indigenous bacteria in the application well close to the cathode; but even there, the microbiome was restored within 15 days. The nZVI-EK treatment proved highly effective in reducing CE contamination and creating a suitable environment for subsequent biodegradation by changing groundwater conditions, promoting transport of nutrients and improving CE availability to soil and groundwater bacteria.
- MeSH
- biodegradace MeSH
- chemické látky znečišťující vodu * MeSH
- ethyleny MeSH
- podzemní voda * MeSH
- železo MeSH
- Publikační typ
- časopisecké články MeSH
Contamination by chloroethenes has a severe negative effect on both the environment and human health. This has prompted intensive remediation activity in recent years, along with research into the efficacy of natural microbial communities for degrading toxic chloroethenes into less harmful compounds. Microbial degradation of chloroethenes can take place either through anaerobic organohalide respiration, where chloroethenes serve as electron acceptors; anaerobic and aerobic metabolic degradation, where chloroethenes are used as electron donors; or anaerobic and aerobic co-metabolic degradation, with chloroethene degradation occurring as a by-product during microbial metabolism of other growth substrates, without energy or carbon benefit. Recent research has focused on optimising these natural processes to serve as effective bioremediation technologies, with particular emphasis on (a) the diversity and role of bacterial groups involved in dechlorination microbial processes, and (b) detection of bacterial enzymes and genes connected with dehalogenation activity. In this review, we summarise the different mechanisms of chloroethene bacterial degradation suitable for bioremediation and provide a list of dechlorinating bacteria. We also provide an up-to-date summary of primers available for detecting functional genes in anaerobic and aerobic bacteria degrading chloroethenes metabolically or co-metabolically.
In recent years, there has been an increase in efforts to improve wastewater treatment as the concentration of dangerous pollutants, such as endocrine disrupting chemicals, in wastewater increases. These compounds, which mimic the effect of hormones, have a negative impact on human health and are not easily removed from water. One way to effectively eliminate these pollutants is to use enzymatically activated materials. In this study, we report on the use of laccase from the white rot fungus Trametes versicolor immobilized onto polyamide 6/chitosan (PA6/CHIT) nanofibers modified using two different spacers (bovine serum albumin and hexamethylenediamine). We then tested the ability of the PA6/CHIT-laccase biocatalysts to eliminate a mixture containing 50μM of two endocrine disrupting chemicals: bisphenol A and 17α-ethinylestradiol. The PA6/CHIT nanofiber matrix used in this study not only proved to be a suitable carrier for immobilized and modified laccase but was also efficient in the removal of a mixture of endocrine disrupting chemicals in three treatment cycles.
- MeSH
- biodegradace MeSH
- chitosan chemie MeSH
- endokrinní disruptory metabolismus MeSH
- enzymy imobilizované metabolismus MeSH
- fungální proteiny metabolismus MeSH
- kaprolaktam analogy a deriváty chemie MeSH
- lakasa metabolismus MeSH
- lidé MeSH
- nanovlákna chemie ultrastruktura MeSH
- polymery chemie MeSH
- Trametes enzymologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
