Arsenic compounds are carcinogenic to humans and are typically removed from contaminated water using various sorbents. The ionic composition plays a significant role in arsenate removal efficiency during the process of water remediation. Here, we quantify the effects of natural ions (chlorides, nitrates, carbonates, sulfates, and phosphates) and humic acid on the removal of arsenates by ferrate(VI) at pH = 6.6. In the experiments, the initial concentration of arsenates was 10 mg L-1 (as As) and the concentrations of ions varied in the range from 5 to 100 mg L-1 of element in ionic form and humic acid. The achieved results show that only phosphate ions had principle influence on the efficiency of arsenate removal by ferrate(VI). The effect of phosphates was elucidated by applying transmission electron microscopy, energy-dispersive X-ray spectroscopy, and low temperature in-field 57Fe Mössbauer spectroscopy to solid samples, prepared under different weight ratios of ferrate(VI), arsenates, and phosphates. These results show three crucial effects of phosphates on the arsenate removal mechanisms. At low P:As weight ratio (up to 1:1), the incorporation of arsenate ions into the crystalline structure of γ-Fe2O3/γ-FeOOH nanoparticles was found to be suppressed by the presence of phosphates. Thus, arsenates were mainly adsorbed onto the surface of γ-Fe2O3/γ-FeOOH nanoparticles. Further increase in the P:As weight ratio (more than 1:1) resulted in the competition between arsenates and phosphates sorption. With the increased concentration of phosphate ions, the number of arsenates on the surface of γ-Fe2O3/γ-FeOOH nanoparticles was reduced. Finally, the complexation of iron(III) ions with phosphate ions occurred, leading to a decrease in the arsenates removal efficiency, which resulted from a lower content of precipitated γ-Fe2O3/γ-FeOOH nanoparticles. All these aspects need to be considered prior to application of ferrate(VI) for arsenates removal in real natural waters.
- MeSH
- adsorpce MeSH
- arseničnany chemie MeSH
- chemické látky znečišťující vodu chemie MeSH
- chloridy chemie MeSH
- čištění vody metody MeSH
- dusičnany chemie MeSH
- fosfáty chemie MeSH
- huminové látky * MeSH
- koncentrace vodíkových iontů MeSH
- sírany chemie MeSH
- spektroskopie Mossbauerova MeSH
- uhličitany chemie MeSH
- železité sloučeniny chemie MeSH
- železo chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
UNLABELLED: An understanding of adherence ability is crucial in many areas, for example, in research on biofilms, evaluation of probiotics or in biotechnology. In all these analyses, the reproducible washing is very important in the prevention of false results. During washing, the force, direction of the flow, position of the pipette tip, number of washing cycles, type of washing solution and the way of removing the washing solution can be sources of inappropriate stress to attached cells. To overcome these problems, we here propose the use of high mass density solutions as flotation agents. As the density of bacteria is lower than that of the flotation solutions, nonattached or weakly attached bacteria are moved to the surface due to hydrostatic force. Caesium chloride, ammonium nitrate and sodium diatrizoate solutions, which are commonly used as FAs, were compared with a standard method of rinsing. Several concentrations of agents were used to investigate the optimal concentration and influence of hydrostatic pressure on adhered micro-organisms. We show that flotation is a rapid method for distinguishing between adhered and weakly attached or loosed cells with reproducible results. Due to its range of possible mass density concentration, the best FA was shown to be caesium chloride. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study that suggests using flotation agents to separate planktonic from adhered bacteria. When a high-density solution is used, buoyancy of bacteria ensures their segregation in the solution. Flotation agents could be used instead of washing procedure, which is inaccurate and hardly reproducible. High-density flotation agents could be used for more precise evaluation of bacterial adherence in many assays, such as research of biofilms or evaluation of probiotics.
Nitrogen discharges from decentralized wastewater treatment (DWT) systems contribute to surface and groundwater contamination. However, the high variability in loading rates, long idle periods and lack of regular maintenance presents a challenge for biological nitrogen removal in DWT. A Tire-Sulfur Hybrid Adsorption Denitrification (T-SHAD) process was developed that combines nitrate (NO3(-)) adsorption to scrap tire chips with sulfur-oxidizing denitrification. This allows the tire chips to adsorb NO3(-) when the influent loading exceeds the denitrification capacity of the biofilm and release it when NO3(-) loading rates are low (e.g. at night). Three waste products, scrap tire chips, elemental sulfur pellets and crushed oyster shells, were used as a medium in adsorption, leaching, microcosm and up-flow packed bed bioreactor studies of NO3(-) removal from synthetic nitrified DWT wastewater. Adsorption isotherms showed that scrap tire chips have an adsorption capacity of 0.66 g NO3(-)-N kg(-1) of scrap tires. Leaching and microcosm studies showed that scrap tires leach bioavailable organic carbon that can support mixotrophic metabolism, resulting in lower effluent SO4(2-) concentrations than sulfur oxidizing denitrification alone. In column studies, the T-SHAD process achieved high NO3(-)-N removal efficiencies under steady state (90%), variable flow (89%) and variable concentration (94%) conditions.
- MeSH
- adsorpce MeSH
- bioreaktory MeSH
- chemické látky znečišťující vodu chemie MeSH
- denitrifikace * MeSH
- dusičnany chemie MeSH
- dusík chemie MeSH
- odpad tekutý - odstraňování ekonomika metody MeSH
- odpadní voda chemie MeSH
- síra chemie MeSH
- tuhý odpad MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
Marine phytoplankton account for about 50% of all global net primary productivity (NPP). Active fluorometry, mainly Fast Repetition Rate fluorometry (FRRf), has been advocated as means of providing high resolution estimates of NPP. However, not measuring CO2-fixation directly, FRRf instead provides photosynthetic quantum efficiency estimates from which electron transfer rates (ETR) and ultimately CO2-fixation rates can be derived. Consequently, conversions of ETRs to CO2-fixation requires knowledge of the electron requirement for carbon fixation (Φe,C, ETR/CO2 uptake rate) and its dependence on environmental gradients. Such knowledge is critical for large scale implementation of active fluorescence to better characterise CO2-uptake. Here we examine the variability of experimentally determined Φe,C values in relation to key environmental variables with the aim of developing new working algorithms for the calculation of Φe,C from environmental variables. Coincident FRRf and (14)C-uptake and environmental data from 14 studies covering 12 marine regions were analysed via a meta-analytical, non-parametric, multivariate approach. Combining all studies, Φe,C varied between 1.15 and 54.2 mol e(-) (mol C)(-1) with a mean of 10.9 ± 6.91 mol e(-) mol C)(-1). Although variability of Φe,C was related to environmental gradients at global scales, region-specific analyses provided far improved predictive capability. However, use of regional Φ e,C algorithms requires objective means of defining regions of interest, which remains challenging. Considering individual studies and specific small-scale regions, temperature, nutrient and light availability were correlated with Φ e,C albeit to varying degrees and depending on the study/region and the composition of the extant phytoplankton community. At the level of large biogeographic regions and distinct water masses, Φ e,C was related to nutrient availability, chlorophyll, as well as temperature and/or salinity in most regions, while light availability was also important in Baltic Sea and shelf waters. The novel Φ e,C algorithms provide a major step forward for widespread fluorometry-based NPP estimates and highlight the need for further studying the natural variability of Φe,C to verify and develop algorithms with improved accuracy.
- MeSH
- Bacteria metabolismus MeSH
- časoprostorová analýza MeSH
- dusičnany chemie MeSH
- ekosystém MeSH
- elektrony * MeSH
- fytoplankton metabolismus MeSH
- koloběh uhlíku * MeSH
- mořská voda chemie mikrobiologie MeSH
- zeměpis MeSH
- životní prostředí MeSH
- Publikační typ
- časopisecké články MeSH
- metaanalýza MeSH
- práce podpořená grantem MeSH
Genotoxic nitrated polycyclic aromatic hydrocarbons (NPAHs) are formed during incomplete combustion processes by reaction of polycyclic aromatic hydrocarbons (PAHs) with atmospheric nitrogen oxides. 1-Nitropyrene, 2-nitrofluorene, and 3-nitrofluoranthene as the dominating substances are used as markers of NPAHs formation by these processes. In the presented study, voltammetric properties and quantification of these compounds and of 5-nitroquinoline (as a representative of environmentally important genotoxic heterocyclic compounds) have been investigated using a mercury meniscus modified silver solid amalgam electrode (m-AgSAE), which represent a nontoxic alternative to traditional mercury electrodes. Linear calibration curves over three orders of magnitude and limits of determination mostly in the 10(-7) mol L(-1) concentration range were obtained using direct current and differential pulse voltammetry. Further, satisfactory HPLC separation of studied analytes in fifteen minutes was achieved using 0.01 mol L(-1) phosphate buffer, pH 7.0 : methanol (15 : 85, v/v) mobile phase, and C(18) reversed stationary phase. Limits of detection of around 1 · 10(-5) mol L(-1) were achieved using amperometric detection at m-AgSAE in wall-jet arrangement for all studied analytes. Practical applicability of this technique was demonstrated on the determination of 1-nitropyrene, 2-nitrofluorene, 3-nitrofluoranthene, and 5-nitroquinoline in drinking water after their preliminary separation and preconcentration using solid phase extraction with the limits of detection around 1 · 10(-6) mol L(-1).
The influence of iron, copper and nitrate ions on free-radical processes in rats and the dependence between dose and effect of pro-oxidants were studied. Rats were divided into 14 groups and administered differing concentrations and combinations of chemicals with drinking water. Concentrations of iron, copper and nitrate in the water were 1, 0.5 and 0.33 of maximum permissible concentrations (MPCs) for every chemical. The action of the investigated pollutants on the intensity of free-radical processes was estimated by the determination of conjugated dienes in liver homogenate and the intensity of Fe2+-induced chemiluminescence of the blood serum. It is estimated that chemicals entering the organism in doses that do not exceed their MPC lead to an increase in free-radical oxidation in comparison to the controls. A maximal effect of iron on the concentration of conjugated dienes was observed in a dose equal to 0.33 MPC, while copper and nitrate possess maximal activity in concentrations of 0.5 MPCs. Fast flash amplitude of chemiluminescence in serum was not dose-dependent in rats obtaining iron and copper, while nitrate had a reverse dose-dependent effect. Total luminosity was maximal in doses of chemicals equal to 0.33 MPCs. The combined action of pollutants was more evident in comparison to isolated chemicals in doses equal to 1 MPC.
- MeSH
- aplikace orální MeSH
- dusičnany chemie metabolismus MeSH
- experimenty na zvířatech MeSH
- játra chemie MeSH
- luminiscence diagnostické užití MeSH
- měď chemie metabolismus MeSH
- oxidační stres účinky léků MeSH
- potkani Wistar MeSH
- sérum chemie MeSH
- statistika jako téma MeSH
- volné radikály chemie metabolismus MeSH
- železo chemie metabolismus MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
Zajímalo nás, zda i u závažných exacerbací vyžadujících hospitalizaci dojde po jejich odeznění ke zmírnění oxidačního stresu. K hodnocení jsme vybrali tři látky podílející se na oxidačním stresu – nitrity (NO2-), nitráty (NO3-), což jsou látky vznikající přeměnou oxidu dusnatého (NO), a malondialdehyd, který je produktem peroxidace lipidů. Koncentrace NO2- i NO3- byly měřeny v kondenzátu vydechovaného vzduchu (KVV), který byl získán na přístroji EcoScreen (VIASYS HealthCare GmbH, Hoechberg, SRN). Soubor tvoří celkem 29 osob, z toho 18 mužů (62,1 %) a 11 (37,9 %) žen hospitalizovaných pro exacerbaci CHOPN. Medián koncentrace NO2- (umol/l) při přijetí byl 5,11; při propuštění 6,58; medián NO3- (umol/l) byl 42,3 resp. 53,0; medián koncentrace malondialdehydu (nmol/l) byl při přijetí 30,5; při propuštění 17,7. U žádného ze sledovaných parametrů nedošlo k signifikantnímu poklesu. Výsledky naší práce dokládají, že u nemocných hospitalizovaných pro exacerbaci CHOPN přes signifikantní zmírnění bronchiální obstrukce nedojde k poklesu parametrů oxidačního stresu (NO2-, NO3- a malondialdehydu).
The aim was to find out whether oxidative stress is reduced after resolution of even severe exacerbations requiring hospitalization. For the assessment, three substances pairticipating in oxidative stress were selected - nitrites (N02-) and nitrates (NO3-), i.e. substances produced by conversion from nitric oxide (NO) and malondialdehyde, a product of lipid peroxidation. Concentrations of NO2- and NO3- were measured in exhaled breath condensate (EBC) collected using the EcoScreen device (VIASYS HealthCare GmbH, Hoechberg, Germany). The group comprised 29 persons, 18 (62.1 %) males and 11 (37.9 %) females hospitalized for a COPD exacerbation. The median concentrations on admission and at discharge were as follows: 5.11 and 6.58 for NO2- (μmol/11, 42.3 and 53.0 for NO3- (μmol/l) and 30.5 and 17.7 for malondialdehyde (nmol/1), respectively. In none of the studied parameters, a significant decrease was observed. The results suggest that despite significeint resolution of bronchial obstruction in patients hospitalized for a COPD exacerbation, oxidative stress parameters (NO2- , N03- and malondialdehyde) are not reduced.
Meat of wild boar with an intial (137)Cs activity concentration of 103 Bq kg(-1) of fresh mass was treated by brining. Dry-salting reduced the (137)Cs activity only by about 12-18%. Subsequent brining was done by using both pure sodium chloride and a mixture of sodium chloride and potassium nitrate. After double-brine exchange, the (137)Cs activity concentration was reduced by at least 72%. The double-brine exchanges were done for two time intervals (the first each 24 h and the second each 7 days). There were no differences in the (137)Cs activity reduction for these two time intervals. From the technological point of view, the repeated exchange of the brine solution represents a relative easy method of (137)Cs activity reduction in contaminated pork meat.
- MeSH
- analýza potravin MeSH
- chlorid sodný chemie MeSH
- dusičnany chemie MeSH
- financování organizované MeSH
- manipulace s potravinami metody MeSH
- maso účinky záření MeSH
- osmolární koncentrace MeSH
- prasata MeSH
- radioaktivní kontaminace potravin analýza MeSH
- radioizotopy cesia analýza chemie MeSH
- roztoky MeSH
- sloučeniny draslíku chemie MeSH
- soli chemie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
Článek se snaží odpovědět na častou otázku veřejnosti, zda je možné pro přípravu kojenecké stravy používat pitnou vodu z vodovodu, nebo zda je nutné používat balenou vodu určenou pro kojence. Pokud voda odpovídá ve všech ukazatelích požadavkům na pitnou vodu, je bezpečná i pro kojence, protože např. současná limitní hodnota dusičnanů v pitné vodě (50 mg/l) je stanovena právě s ohledem na prevenci kojenecké methemoglobinémie. Má-li spotřebitel pochybnosti o stálosti mikrobiologické kvality dodávané vody, může vodu pro jistotu krátce převařit. Někdy může docházet k případům, kdy voda sice splňuje legislativní hygienické požadavky, ale vzhledem k vyššímu obsahu některých jejích přirozených součástí (rozpuštěné látky, sodík, sírany, fluoridy, hořčík atd.) může být pro kojence méně vhodná. Autor uvádí doporučené hodnoty obsahu těchto látek v kojenecké vodě.
Here the author attempts to answer a question frequently asked by the public: when preparing infant formula, can tap water be ušed or do we need to use bottled water marketed for infants? If the water in question meets the drinking water standards for all indicators, it is safe for infants as well, since, for instance, the current limit for nitrates in drinking water (50 mg/l) was set up with respect to the prevention of infant methemoglobinemia. If the consumer is in any doubt as to the stability of microbiological quality of the water supply, the water should be boiled shortly to make sure it is safe. Nevertheless, in some instances, although meeting the regulátory safety requirements, the water may appear less suitable for infants because it contains higher amounts of some naturally present minerals (total dissolved solids, sodium, sulphates, fluorides, magnesium, etc). The recommended content of particular minerals in drinking water intended for infant consumption is outlined in the article.
