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1.
J Environ Manage ; 273: 111091, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32741758

RESUMO

Fireworks events during the annual Indian festival of Diwali has been heavily criticised in recent times. Perchlorate is an essential component of fireworks. The effects of the fireworks on perchlorate (ClO4-) concentrations and quality parameters of the ambient waters of Ahmedabad, Gujarat, India were studied. As expected, ClO4- concentrations in the (Kankaria) lake adjoining the fireworks site were below detection prior to the Diwali event and increased to 0.97 and 1.03 µg/L at 48 and 288 h after the event, respectively. However, samples from the Sabarmati River surprisingly contained an extremely high concentration of ClO4- (65 µg/L) one day before the event, which decreased to 1.14 µg/L after 48 h and was below detection limit after 7 days of the event. This finding raises questions such as: (a) which has greater impact, fireworks manufacturing or burning; (b) can unregulated release of untreated effluents be a major critical source of pollution needing immediate attention from removal, environmental regulation and policy perspectives; c) is policy pertaining to unskilled labour in the manufacturing of fireworks and other ClO4--containing products needed in developing countries; and d) is ClO4- being a strong oxidiser, detrimental to the soil, groundwater, and aquatic environment?


Assuntos
Poluentes Atmosféricos/análise , Água Subterrânea , Monitoramento Ambiental , Índia , Percloratos/análise
2.
Acta Crystallogr C Struct Chem ; 76(Pt 7): 663-672, 2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32624513

RESUMO

The reactivity of the cobalt(III) complexes dichlorido[tris(2-aminoethyl)amine]cobalt(III) chloride, [CoCl2(tren)]Cl, and dichlorido(triethylenetetramine)cobalt(III) chloride, [CoCl2(trien)]Cl, towards different amino acids (L-proline, L-asparagine, L-histidine and L-aspartic acid) was explored in detail. This study presents the crystal structures of three amino acidate cobalt(III) complexes, namely, (L-prolinato-κ2N,O)[tris(2-aminoethyl)amine-κ4N,N',N'',N''']cobalt(III) diiodide monohydrate, [Co(C5H8NO2)(C6H18N4)]I2·H2O, I, (L-asparaginato-κ2N,O)[tris(2-aminoethyl)amine-κ4N,N',N'',N''']cobalt(III) chloride perchlorate, [Co(C4H7N2O3)(C6H18N4)](Cl)(ClO4), II, and (L-prolinato-κ2N,O)(triethylenetetramine-κ4N,N',N'',N''')cobalt(III) chloride perchlorate, [Co(C4H7N2O3)(C6H18N4)](Cl)(ClO4), V. The syntheses of the complexes were followed by characterization using UV-Vis spectroscopy of the reaction mixtures and the initial rates of reaction were obtained by calculating the slopes of absorbance versus time plots. The initial rates suggest a stronger reactivity and hence greater affinity of the cobalt(III) complexes towards basic amino acids. The biocompatibility of the complexes was also assessed by evaluating the cytotoxicity of the complexes on cultured normal human fibroblast cells (WS1) in vitro. The compounds were found to be nontoxic after 24 h of incubation at concentrations up to 25 mM.


Assuntos
Cobalto/química , Complexos de Coordenação/química , Histidina/química , Aminoácidos/química , Cristalografia por Raios X , Ligantes , Percloratos/química
3.
Food Chem ; 328: 127113, 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-32474239

RESUMO

In view of the high polarity and ubiquitous occurrence of perchlorate, achieving an ultra-trace analysis has become a challenging task. The present study aimed to develop a simple and generic pretreatment protocol based on cold-induced liquid-liquid extraction to efficiently extract perchlorate from tea and dairy products and remarkably decrease potential matrix interferences and laborious cleanup. By optimizing the pretreatment conditions, the enrichment factor of perchlorate increased by 7.79 times under the compromise between the matrix effect and extraction recovery. The validated method presented satisfactory selectivity, linearity, accuracy, precision, and matrix effect, providing recoveries of 78.2%-106.2% with RSDr ranging from 1.2% to 7.9% and RSDR less than 10.7% for tea and dairy products. This pretreatment protocol depended only on shaking, freezing, and centrifugation in one step, without additional equipment or tedious operations, which will be explored to a greater extent in complex biological or food matrices.


Assuntos
Laticínios/análise , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Extração Líquido-Líquido/métodos , Percloratos/análise , Chá/química , Centrifugação/métodos , Análise Custo-Benefício , Análise de Alimentos/economia , Congelamento , Extração Líquido-Líquido/economia , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Fatores de Tempo
4.
Food Chem ; 330: 127205, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32521397

RESUMO

The incidence of endocrine disruptors, both possible (glyphosate and glufosinate), and demonstrated (perchlorate and chlorate), was estimated in baby food commodities (meat, fish, cheese, vegetable and fruit). Ion-chromatography coupled to high resolution mass spectrometry analysis of the 105 samples did not show traces of glyphosate, glufosinate or their metabolites, while in 10.5% of the samples a quantifiable amount of perchlorate was found. Some samples based on fruit and vegetables revealed a substantial amount of chlorate, especially the preparations that contained carrots and potatoes: five samples were in a concentration range of 40-120 µg kg-1, while one homogenized pear sample reached 372.2 µg kg-1. The pure meat samples revealed occasional chlorate appearance, with less than 10 µg kg-1. This is the first report of chlorate evaluated in various types of baby food and may serve as symptomatic data regarding its occurrence in infant/toddler diets. Therefore, effective monitoring programs and subsequent strict regulations are strongly required.


Assuntos
Cloratos/análise , Contaminação de Alimentos/análise , Herbicidas/análise , Alimentos Infantis/análise , Percloratos/análise , Animais , Cloratos/química , Produtos Pesqueiros/análise , Frutas/química , Herbicidas/química , Carne/análise , Percloratos/química , Verduras/química
5.
Environ Pollut ; 264: 114682, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32380400

RESUMO

Perchlorate occurs naturally in the environment in deposits of nitrate and can be formed in the atmosphere and precipitate into soil. However, little is known about the occurrence and levels of perchlorate in soils and fertilizers in Chile and its impacts on agricultural systems and food safety. In this study, concentrations of perchlorate were determined in 101 surface soils and 17 fertilizers [nitrogenous (n = 8), nitrogen-phosphorous-potassium (NPK; n = 3), phosphate (n = 2) and non-nitrogenous (n = 4)] collected across Chile from 2017 to 2018. Our results show that perchlorate was detected mainly in agricultural soils (mean: 0.32 ng g-1), grassland rotation sites (0.41 ngg-1) and urban locations (0.38 ng g-1). Interestingly, elevated concentrations of perchlorate (9.66 and 54.0 ng g-1) were found in agricultural soils. All fertilizers contained perchlorate: nitrogenous fertilizers (mean: 32.6 mg kg-1), NPK (mean: 12.6 mg kg-1), non-nitrogenous fertilizers (mean: 10.2 mg kg-1) and phosphates (mean: 11.5 mg kg-1). Only one type of nitrogenous fertilizer (KNO3: 95.3 mg kg-1) exceeded the international regulation limit (50 mg kg-1). For two agronomic practices, the content of perchlorate in lettuce increased as the fertilizer application rate increased, with fertigation promoting a more significant accumulation. However, the concentrations generally remained below regulatory values. Our results suggest that fertilizers constitute an important source of perchlorate in soils.


Assuntos
Alface , Solo , Agricultura , Chile , Fertilizantes/análise , Percloratos
6.
World J Microbiol Biotechnol ; 36(5): 75, 2020 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-32390104

RESUMO

Biofilm reactors retain microbial cells in the form of biofilm which is attached to free moving or fixed carrying materials, thus providing a high active biomass concentration and automatic liquid and solid separation. Nowadays, microbial biofilm reactors have been widely used in high-strength wastewater treatment where very high pollutant removal efficiency is required, which usually requires excessive space and aeration energy for conventional activated sludge-based treatment. This paper provides an overview of microbial biofilm reactors developed over the last half-century, including moving bed biofilm reactor (MBBR), trickling filter (TF) reactor, rotating biological contactor (RBC), membrane biofilm reactor (MBfR), passive aeration simultaneous nitrification and denitrification (PASND) biofilm reactor, for their applications in high-strength wastewater treatment of not only removing carbon, nitrogen, sulphur but also a variety of oxidized contaminants including perchlorate and bromate. Despite the advance of biofilm reactor that exhibits high resistance to excessive pollutants loading, its drawbacks both from engineering and microbiological point of view are reviewed. The future prospects of biofilm reactor are also discussed in this review paper.


Assuntos
Biofilmes , Reatores Biológicos/microbiologia , Águas Residuárias/microbiologia , Purificação da Água/métodos , Biomassa , Bromatos/metabolismo , Carbono/metabolismo , Desnitrificação , Microbiologia Industrial , Membranas , Nitrificação , Nitrogênio , Percloratos/metabolismo , Esgotos/microbiologia
7.
J Environ Manage ; 265: 110566, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32275236

RESUMO

This work focuses on disinfection of water using electrolysis with diamond coatings avoiding or minimizing the formation of hazardous chlorates and perchlorates using a special type of commercial cells designed by CONDIAS (Itzehoe, Germany) in two different sizes: the CabECO and the MIKROZON cells. In these cells, the electrolyte that separates the anode and cathode is a proton exchange membrane. This helps to minimize the production of perchlorate and this behavior is enhanced in the smallest cell for which the very low contact times between the electrodes and the water allows to avoid the production of perchlorates when operating in a single-pass mode, which becomes a really remarkable point. In this paper, we report tests in which we demonstrate this outstanding performance and we also explain the differences observed in the two cells operating with the same water.


Assuntos
Cloratos , Poluentes Químicos da Água , Diamante , Desinfecção , Eletrodos , Alemanha , Oxirredução , Percloratos
8.
Sci Total Environ ; 720: 137426, 2020 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-32325562

RESUMO

Quantitative information about fluxes of perchlorate in the environment is lacking. This study reports analyses of perchlorate in various environmental waters sampled from rural headwater catchments in the Thames River basin in southern Ontario (Canada) that provide evidence about the fluxes and fate of perchlorate in the environment. Concentrations in streams (16 to 1047 ng/L) were used to estimate exports from these rural catchments (228-1843 mg/(ha·year)), atmospheric deposition (1480 ± 230 mg/(ha·year)), as well as variable rates of microbial degradation of perchlorate, which appeared to be enhanced in catchments with higher percentages of wetlands. Groundwater data supported earlier evidence that degradation of perchlorate occurs in the subsurface under oxygen-depleted conditions. The stream data suggest that the rate of degradation varies strongly between catchments and ranges up to >1000 mg/(ha·year).


Assuntos
Percloratos/análise , Monitoramento Ambiental , Água Subterrânea , Ontário , Rios
9.
Sci Total Environ ; 719: 137411, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32145491

RESUMO

The application of excessive fertilizer represents a primary source of entry for perchlorate into crop systems and thus has raised widespread concern regarding food safety. Several studies have reported the occurrence of perchlorate in vegetables. However, limited information is available on the fate of perchlorate in the soil-plant system. In this study, we performed field experiments to evaluate the effects of the application rate of Chilean nitrate fertilizer and the type of fertilization (manual or fertigation) on the uptake of perchlorate by plants grown in open fields. Interestingly, in the control, chard and spinach accumulated 21.3 and 25.9 µg kg-1, respectively. For both agronomic practices, the content of perchlorate in chard and spinach increased as the fertilizer application rate increased, with fertigation promoting more significant accumulations. Spinach accumulated almost two times more perchlorate than chard for all treatments; however, the concentrations generally remained below regulatory values. The intake of spinach and chard presented a low risk to human health for all age groups. These findings enhance our understanding of the environmental impact of the use of fertilizers in agriculture and food safety.


Assuntos
Beta vulgaris , Solo , Spinacia oleracea , Agricultura , Chile , Fertilizantes , Percloratos , Medição de Risco
10.
Chemosphere ; 247: 125947, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32069722

RESUMO

A novel, ex-situ remediation process for perchlorate contaminated soil is reported in this study. This approach comprises washing the contaminated soil with water, followed by treatment of the wash water in a bioreactor. The treated water reused for the next batch of soil, and the cycle continued. The pilot-scale treatment unit comprising of a soil washing unit (0.75 m3) and a fixed-film bioreactor (140 L), both connected in series for continuous operation for a period of three months. The bioreactor was inoculated with a novel perchlorate reducing microbial consortium comprising Serratia marcescens (Gen bank no. HM751096), Bacillus pumilus (Gen bank no. JQ820452) and Micrococcus sp. (Gen bank no. KJ410671). The microbial activity was supported by glucose (glucose/perchlorate ratio = 5), and trace mineral solution. In a typical washing cycle, 2.5 g perchlorate (KClO4) spiked in 670 kg soil was completely removed in three washing cycles, that completed in 6.3 h consuming ∼360 L water. The pooled wash water containing perchlorate at 8.5 mg/L was treated completely in the bioreactor operated at 4.5 h HRT and -200 mV ORP. Compared with both in-situ and ex-situ remediation methods reported, the present approach has many advantages for treating perchlorate contaminated soil.


Assuntos
Recuperação e Remediação Ambiental/métodos , Percloratos/metabolismo , Poluentes do Solo/metabolismo , Reatores Biológicos , Poluição Ambiental , Percloratos/análise , Solo , Microbiologia do Solo , Poluentes do Solo/análise , Purificação da Água
11.
PLoS One ; 15(2): e0229085, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32084174

RESUMO

The sodium iodide symporter (NIS) transports iodide, which is necessary for thyroid hormone production. NIS also transports other monovalent anions such as tetrafluoroborate (BF4-), pertechnetate (TcO4-), and thiocyanate (SCN-), and is competitively inhibited by perchlorate (ClO4-). However, the mechanisms of substrate selectivity and inhibitor sensitivity are poorly understood. Here, a comparative approach was taken to determine whether naturally evolved NIS proteins exhibit variability in their substrate transport properties. The NIS proteins of thirteen animal species were initially assessed, and three species from environments with differing iodide availability, freshwater species Danio rerio (zebrafish), saltwater species Balaenoptera acutorostrata scammoni (minke whale), and non-aquatic mammalian species Homo sapiens (human) were studied in detail. NIS genes from each of these species were lentivirally transduced into HeLa cells, which were then characterized using radioisotope uptake assays, 125I- competitive substrate uptake assays, and kinetic assays. Homology models of human, minke whale and zebrafish NIS were used to evaluate sequence-dependent impact on the organization of Na+ and I- binding pockets. Whereas each of the three proteins that were analyzed in detail concentrated iodide to a similar degree, their sensitivity to perchlorate inhibition varied significantly: minke whale NIS was the least impacted by perchlorate inhibition (IC50 = 4.599 µM), zebrafish NIS was highly sensitive (IC50 = 0.081 µM), and human NIS showed intermediate sensitivity (IC50 = 1.566 µM). Further studies with fifteen additional substrates and inhibitors revealed similar patterns of iodide uptake inhibition, though the degree of 125I- uptake inhibition varied with each compound. Kinetic analysis revealed whale NIS had the lowest Km-I and the highest Vmax-I. Conversely, zebrafish NIS had the highest Km and lowest Vmax. Again, human NIS was intermediate. Molecular modeling revealed a high degree of conservation in the putative ion binding pockets of NIS proteins from different species, which suggests the residues responsible for the observed differences in substrate selectivity lie elsewhere in the protein. Ongoing studies are focusing on residues in the extracellular loops of NIS as determinants of anion specificity. These data demonstrate significant transport differences between the NIS proteins of different species, which may be influenced by the unique physiological needs of each organism. Our results also identify naturally-existing NIS proteins with significant variability in substrate transport kinetics and inhibitor sensitivity, which suggest that the affinity and selectivity of NIS for certain substrates can be altered for biotechnological and clinical applications. Further examination of interspecies differences may improve understanding of the substrate transport mechanism.


Assuntos
Boratos/metabolismo , Animais , Linhagem Celular , Células HeLa , Humanos , Cinética , Lentivirus/genética , Percloratos/metabolismo , Simportadores/metabolismo , Tiocianatos/metabolismo , Baleias , Peixe-Zebra
12.
J Dairy Sci ; 103(2): 1208-1214, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31837793

RESUMO

The objective of this study was to assess the effects of electrochemically activated drinking water (ECW) on milk chlorate, milk perchlorate, milk iodine, milk composition, milk fatty acid profile, and overall performance of dairy cows. Ten Red Danish cows in mid-lactation (203 ± 31 d in milk; average ± SD) were chosen from these 2 groups for intensive sampling. The treated group drank water with 4 ppm of ECW (29 mg/L of chlorate of Neuthox, Danish Clean Water A/S, Sønderborg, Denmark). The treatment lasted 60 consecutive days, with milk and water sampling on d 0, 30, and 60. Additionally, milk samples from both the control group and treated group were taken on d 90 to assess if any carry-over effect was present. Interactions between period and milk yield and somatic cell for the full group and period and milk fat content and milk urea nitrogen in the selected animals occurred. Milk yield was not significantly affected by treatments. Milk fat, milk fatty acid profile, chlorate, perchlorate, and iodine contents were not significantly different between treatments. Milk urea increased, whereas ß-hydroxybutyrate and somatic cell count decreased significantly in the treated groups. Results showed that at a dosing of 4 ppm of ECW, both chlorate and perchlorate concentrations in milk (<0.002 mg/kg) were low, and no deleterious effects on milk production or milk chemical composition were observed. These data can be of use when assessing the effects of ECW on milk and milk powder chlorate and perchlorate levels and provide a context for assessing the potential for influencing human health under the conditions prevailing on a commercial dairy farm.


Assuntos
Água Potável/química , Leite/química , Ácido 3-Hidroxibutírico/análise , Animais , Bovinos , Cloratos/análise , Dinamarca , Dieta/veterinária , Técnicas Eletroquímicas , Ácidos Graxos/análise , Feminino , Iodo/análise , Lactação , Percloratos/análise
13.
ISME J ; 14(2): 450-462, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31659234

RESUMO

Inhibitors can be used to control the functionality of microbial communities by targeting specific metabolisms. The targeted inhibition of dissimilatory sulfate reduction limits the generation of toxic and corrosive hydrogen sulfide across several industrial systems. Sulfate-reducing microorganisms (SRM) are specifically inhibited by sulfate analogs, such as perchlorate. Previously, we showed pure culture SRM adaptation to perchlorate stress through mutation of the sulfate adenylyltransferase, a central enzyme in the sulfate reduction pathway. Here, we explored adaptation to perchlorate across unconstrained SRM on a community scale. We followed natural and bio-augmented sulfidogenic communities through serial transfers in increasing concentrations of perchlorate. Our results demonstrated that perchlorate stress altered community structure by initially selecting for innately more resistant strains. Isolation, whole-genome sequencing, and molecular biology techniques allowed us to define subsequent genetic mechanisms of adaptation that arose across the dominant adapting SRM. Changes in the regulation of divalent anion:sodium symporter family transporters led to increased intracellular sulfate to perchlorate ratios, allowing SRM to escape the effects of competitive inhibition. Thus, in contrast to pure-culture results, SRM in communities cope with perchlorate stress via changes in anion transport and its regulation. This highlights the value of probing evolutionary questions in an ecological framework, bridging the gap between ecology, evolution, genomics, and physiology.


Assuntos
Evolução Molecular , Percloratos/toxicidade , Sulfatos/metabolismo , Ânions/metabolismo , Bactérias/genética , Bactérias/metabolismo , Transporte Biológico , Oxirredução , Percloratos/metabolismo , Sulfato Adenililtransferase/genética
14.
Anal Chim Acta ; 1094: 11-17, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31761036

RESUMO

Perchlorate is an environmental contaminant that originates from anthropogenic as well as natural sources. The health effects of perchlorate with respect to the thyroid function are well known. The capabilities of the inductively coupled plasma mass spectrometry (ICPMS) has been recently expanded by coupling with tandem mass spectrometry. The advantages of HPLC-ICPMS/MS has not yet been thoroughly assessed for chlorine speciation analysis. We report a rapid and simple method for perchlorate determination in ground, tap, and river water and we show that the ICPMS/MS offers as a chromatographic detector at least 10-fold improvement in the detection limit relative to single quadrupole ICPMS. The achieved limit of detection was 0.3 µg Cl L-1 perchlorate and could be yet improved by simple freeze-drying (down to ca. 50 ng Cl L-1, based on the river water matrix), which is comparable with HPLC-ESIMS/MS, with the advantage of eliminating the need for the 18O-perchlorate isotopically labeled internal standard. The method was validated in the various water matrices in terms of recovery at levels 5.0-250 µg Cl L-1 (±10%), repeatability (RSD<5%), and linearity (r2 = 0.9999), and revealed the presence of trace levels in the Mur river water (0.33 ±â€¯0.04 µg Cl L-1). Carbon was found to significantly decrease signal response for chlorine, and we shed light on the general effects of carbonate on chlorine speciation in hard water analysis.


Assuntos
Água Potável/análise , Água Subterrânea/análise , Percloratos/análise , Rios/química , Poluentes Químicos da Água/análise , Áustria , Carbono/química , Cromatografia Líquida de Alta Pressão , Limite de Detecção , Espectrometria de Massas em Tandem
15.
Chemosphere ; 240: 124953, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31574435

RESUMO

Chemical characterization of PM2.5 and PM10 is important to identify potential compounds that induce biological responses that translate into cardio-respiratory health problems. This study shows the reliability of the use of crystalline phases, identified in samples from receptor sites, as source markers, helping researchers to infer the main sources of air pollution, even without the use of receptor models. PM2.5 and PM10 samples were collected at two sites in an urban industrialized region located at southeast of Brazil and analyzed by Synchrotron X-ray Diffraction to identify crystalline compounds. Results show 5 PM10 and PM2.5 species not previously reported in the literature. We propose reaction mechanisms for these species and identify specific sources for each crystalline phase found: BaTiO3 was found in PM10 receptor samples and proved to be a vehicular marker formed during brake action; maghemite (γ-Fe2O3), pyracmonite [(NH4)3Fe(SO4)3], ammonium perchlorate (NH3OHClO4) and potassium ferrate (K2Fe2O4) were found in PM2.5 proved to be markers of industrial activities. The crystalline phases found in PM samples from receptor sites and the mechanisms of reactions showed the reliability of the use of crystalline phases as source markers in the identification of potential sources of air pollution without misinterpretation of the likely source.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar/análise , Monitoramento Ambiental/métodos , Material Particulado/análise , Material Particulado/química , Sulfato de Amônio/análise , Compostos de Bário/análise , Brasil , Compostos Férricos/análise , Indústrias , Compostos de Ferro/análise , Tamanho da Partícula , Percloratos/análise , Compostos de Potássio/análise , Compostos de Amônio Quaternário/análise , Reprodutibilidade dos Testes , Síncrotrons , Titânio/análise , Difração de Raios X/métodos
16.
Water Res ; 171: 115397, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31875569

RESUMO

Nitrate (NO3-) affected perchlorate (ClO4-) reduction in a membrane batch biofilm reactor (MBBR), even though the electron donor, CH4, was available well in excess of its demand. For example, the perchlorate-reduction rate was 1.7 mmol/m2-d when perchlorate was the sole electron acceptor, but it dropped to 0.64 mmol/m2-d when nitrate also was present. The perchlorate-reduction rate returned to 1.60 mmol/m2-d after all nitrate was consumed. Denitratisoma and Azospirillum were main genera involved in perchlorate and nitrate reduction, and both could utilize NO3- and ClO4- as electron acceptors. Results of the reverse transcription-polymerase chain reaction (RT-PCR) showed that transcript abundances of nitrate reductase (narG), nitrite reductase (nirS), and perchlorate reductase (pcrA) increased when the perchlorate and nitrate concentrations were higher. Specifically, pcrA transcripts correlated to the sum of perchlorate and nitrate, rather than perchlorate individually. Analysis based on Density Functional Theory (DFT) suggests that bacteria able to utilize both acceptors, preferred NO3- over ClO4- due to nitrate reduction having lower energy barriers for proton and electron transfers.


Assuntos
Biofilmes , Percloratos , Reatores Biológicos , Metano , Nitratos , Oxirredução
17.
Carbohydr Res ; 486: 107830, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31627048

RESUMO

Selective acetolysis of the primary benzyloxy groups in a wide variety of carbohydrate derivatives was achieved in excellent yield using acetic anhydride and perchloric acid supported over silica (HClO4-SiO2) as a solid acid catalyst in a fast reaction condition without using any organic solvent. The reaction condition is significantly rapid and can be scaled up for its use in the multi-step oligosaccharide synthesis.


Assuntos
Carboidratos/química , Anidridos Acéticos/química , Catálise , Cinética , Percloratos/química , Dióxido de Silício/química
18.
Se Pu ; 37(10): 1064-1070, 2019 Oct 08.
Artigo em Chinês | MEDLINE | ID: mdl-31642285

RESUMO

An analytical method based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed for detecting chlorate and perchlorate residues in milk power. Chlorate and perchlorate in milk power were extracted using a 0.1% (v/v) formic acid-acetonitrile solution. The extract was centrifuged at 10000 r/min for 10 min, and the supernatant was cleaned up on a PRiME HLB column. Separation of chlorate and perchlorate was performed on an ion-exchange column (Thermo Scientific Acclaim TRINITY P1, 50 mm×2.1 mm, 3 µm) by gradient elution using acetonitrile and 20 mmol/L ammonium acetate solution as the mobile phase. The analytes were identified by MS/MS. Quantification was achieved using internal standards. Chlorate and perchlorate demonstrated good linearity in the ranges of 2.0-40.0 and 1.0-20.0 µg/L, respectively, with correlation coefficients (r2) greater than 0.999. The limits of quantification (LOQs) of chlorate and perchlorate were found to be 15.0 and 7.5 µg/kg, respectively. The recoveries of chlorate and perchlorate ranged from 89.24% to 107.85% at the three spike levels of 30.0, 60.0, and 120.0, and 15.0, 30.0, and 60.0 µg/kg, respectively, with relative standard deviations (RSDs) ranging from 3.15% to 10.42% (n=6). This method is convenient, rapid, accurate, and efficient, thus demonstrating its suitability for use in the determination of chlorate and perchlorate in milk power.


Assuntos
Cloratos/análise , Contaminação de Alimentos/análise , Leite/química , Percloratos/análise , Animais , Cromatografia Líquida de Alta Pressão , Espectrometria de Massas em Tandem
19.
Environ Int ; 133(Pt B): 105191, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31639604

RESUMO

BACKGROUND: Perchlorate, nitrate, and thiocyanate are well-known thyroid disrupters and may contribute to changes in body weight. However, the associations between environmental exposure to these chemicals and obesity-related outcomes remain unclear. OBJECTIVES: We aim to examine the urinary levels of perchlorate, nitrate, and thiocyanate and their associations with obesity and abdominal obesity in the U.S. METHODS: Here, we investigated the data of 16,265 adults aged 20-85 years from the National Health and Nutritional Examination Survey (NHANES) in 2001-2014. Urinary levels of perchlorate, nitrate, and thiocyanate were measured by ion chromatography combined with electrospray tandem mass spectrometry. Obesity and abdominal obesity were defined by the body mass index and waist circumference, respectively. Logistic regression models were used to estimate the associations. RESULTS: Overall, 5794 (35.6%) cases of obesity and 9090 cases (55.9%) of abdominal obesity were observed among the participants. In multivariable-adjusted logistic regression models, urinary nitrate was inversely associated with obesity (p = 0.0022 for trend), while urinary thiocyanate was positively related to obesity (p < 0.001 for trend). Compared with the lowest quartile, the odds ratios with 95% confidence intervals (CIs) across increasing quartiles were 0.95 (95% CI, 0.83-1.08), 0.88 (0.75-1.03), and 0.74 (0.60-0.90) for urinary nitrate and 1.31 (1.16-1.48), 1.53 (1.36-1.73), and 1.73 (1.47-2.03) for urinary thiocyanate. Urinary perchlorate was not correlated with obesity. Similar associations were also found between exposure to these chemicals and abdominal obesity. CONCLUSIONS: A higher exposure to urinary nitrate was associated with a lower risk of obesity, while a positive association was observed for urinary thiocyanate. These findings emphasize the need to longitudinally evaluate environmental exposure to perchlorate, nitrate, and thiocyanate with respect to their effect on obesity in humans.


Assuntos
Exposição Ambiental/estatística & dados numéricos , Nitratos/toxicidade , Obesidade/induzido quimicamente , Percloratos/toxicidade , Tiocianatos/toxicidade , Adulto , Idoso , Idoso de 80 Anos ou mais , Índice de Massa Corporal , Peso Corporal , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Inquéritos Nutricionais , Circunferência da Cintura , Adulto Jovem
20.
Artigo em Inglês | MEDLINE | ID: mdl-31553683

RESUMO

Perchlorate is a low molecular weight highly soluble anion. It occurs naturally in the environment, primarily near potash deposits and in arid regions. The determination of perchlorate in human milk is of interest in vulnerable populations such as infants and pregnant women. In this study, a sensitive and selective isotope dilution ion chromatography/tandem mass spectrometry (ID IC-MS/MS) method was developed and validated for the determination of perchlorate in human milk samples collected from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study. The limit of detection (LOD) was 0.27 µg·kg-1 for human milk. A total of 439 human milk samples were analysed with measurable levels of perchlorate in most of the milk samples, and the mean value was 7.62 ± 32.7 µg·kg-1. This project provided important information related to perchlorate levels in human milk collected across Canada and the extent to which pregnant women and their infants may be exposed to perchlorate. A dietary exposure assessment was also conducted in infants based on the measured values in human milk. The mean perchlorate probable daily intakes (PDIs) for infants consuming human milk were 0.31 ± 0.07 µg/kg bw/day for infants under 1 year and 0.17 ± 0.10 µg/kg bw/day for infants between 1 and 3 years old. None of the estimates exceeded the FAO/WHO provisional maximum tolerable daily intake (PMTDI) of 10 µg/kg bw/day.


Assuntos
Exposição Ambiental/análise , Contaminação de Alimentos/análise , Fórmulas Infantis/química , Leite Humano/química , Percloratos/análise , Adulto , Feminino , Humanos , Lactente , Recém-Nascido , Pessoa de Meia-Idade , Gravidez , Adulto Jovem
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