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1.
Environ Res ; 185: 109433, 2020 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-32247152

RESUMO

The increasing production of eco-friendly nanoparticles like biosynthesized nanoparticles (BNPs) calls for study on their environmental and biological safety. Herein, the impact of natural organic matter on the toxicity of BNPs was studied. Using leaf extract of herbal plant Allium fistulosum, the Allium fistulosum-silver nanoparticles (AF-AgNPs) were synthesized with the yield of around 100% and used to explore the impacts of natural organic matter (Suwannee river humic acid) on their toxicity to green microalgae Chlorella vulgaris. The results showed that the as-prepared AF-AgNPs could decrease the end-points of biomass and chlorophyll a content of C. vulgaris in a dose-dependent manner. In addition, AF-AgNPs enhanced algal aggregation and decreased size of cells, especially at higher concentrations. However, organic matter showed an ameliorative effect on the toxicity of AF-AgNPs, and significant enhancement of biomass and chlorophyll a content (p < 0.05) were observed in media treated with higher contents of AF-AgNPs. Organic matter could also prevent more cellular aggregation and size reduction of C. vulgaris. Our results are helpful for understanding the effects of organic matter on the toxicity of BNPs to aquatic organisms.

2.
J Hazard Mater ; 392: 122495, 2020 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-32208313

RESUMO

In this study, nano selenium functionalized zinc oxide nanorods, NanoSe@ZnO-NR, was prepared, characterized and investigated for Hg(II) removal from waters of different types. The study results revealed that the material showed a superior adsorption capacity (qm, 1110 mg g-1) and excellent distribution coefficient (Kd, 9.11 × 108 mL g-1) which is two or more orders above most of the adsorbents reported in the literature. It should be also known that, 30 mg of the adsorbent can quickly reduce 10 mg L-1 Hg(II) to undetectable level from 10 mL of sample solution. The adsorption data were well explained with the pseudo-second order kinetic model and Langmuir adsorption isotherm model. Besides, the capturing capability of the material is independent on the pH change (2-12), selective against interfering cations, and exhibited fast kinetics (equilibrium time, ∼1 min). The NanoSe@ZnO-NR performance was also tested on real samples from different origin, surface waters (tap, lake and river) and wastewaters (effluent and influent), and complete removal and ≥99.2% removal efficiency was observed at 0.01 and 10 mg L-1 spiking levels, respectively. Therefore, NanoSe@ZnO-NR can be considered as a potential adsorbent in advancing the wastewater treatment technology.

3.
Sci Total Environ ; 723: 138050, 2020 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-32217391

RESUMO

Health concerns of silver nanoparticles (AgNPs) emerged with the increase of their industrial and biomedical application and thus human exposure. The highly dynamic properties of AgNPs lead to coexposure to nanoparticulate and ionic silver, and the combined effects of different Ag species might alter their individual toxicity. Herein, the toxicity of AgNPs combined with ionic Ag+ toward the rat was investigated after intravenous (i.v.) exposure to either AgNPs (5 mg/kg), Ag+ (5 mg/kg), or a mixture of Ag+ and AgNPs (5 mg/kg for both). Comparable results by histopathological and biochemical studies revealed that the exposure to individual AgNPs causes no apparent toxicity in rats, while Ag+ ions at the same dose induced marked acute toxicity. More importantly, while there was a negligible combined effect on the Ag accumulation, the less toxic AgNPs ameliorated Ag+ induced toxicity to rat organs after coexposure to the mixture of Ag+ and AgNPs, which might result from the complexation of Ag+ with the thiols like metallothioneins. Therefore, the combined toxicity of particulate and ionic Ag was complicated by their individual toxicities and also their interaction with intracellular detoxification biomolecules, regardless of differences in Ag accumulation. Although further investigations are still needed for the potential toxic mechanisms of the coexposed AgNPs and Ag+, considerations of the combined toxicity of different Ag species will reflect more accurate assessments of their health impacts.

4.
J Environ Sci (China) ; 91: 85-91, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32172985

RESUMO

The widespread use of nano-enabled water treatment composites (NWTCs) can result in the release of nanoparticles (NPs) into environmental waters. Studying the release of NPs from NWTCs is of great significance for evaluating the material stability, and environment and biological safety. This work evaluated the amount and species of Zr released from a NWTC, a ZrO2/polymer composite (HZO@D201), during the treatment of electroplating wastewater. About 5 g of the HZO@D201 particles, consisting of porous spheres (0.8 mm in diameter) loaded with ZrO2 NPs, were packed into a glass column (130 mm in length and 20 mm in diameter) and treated with wastewater at a flow rate of 25 mL/hr. The release of Zr occurred mainly in the initial stages of water treatment, decreased with the increase of treatment volume, and approached an equilibrium value of approximately 3.79 µg/L at the treatment volume of about 800 bed volumes. The total amount of Zr released in the effluent was in the range of 2.62-140 µg/L, which was mainly present in the form of ZrO2 NPs. The amounts of Zr released under acidic and alkaline conditions were markedly higher than that under neutral conditions, while the presence of humic acid significantly inhibited the release of Zr. Our study implied that the NWTCs could be a source of engineered NPs in environmental waters, and should be considered in evaluating the safety of ZrO2/polymer composites in water treatment.

5.
J Cell Biochem ; 2020 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-32052496

RESUMO

The connection between circular RNAs (circRNAs) and gastric cancer has been reported widely in recent years. However, previous studies have focused mainly on circRNAs from gastric cancer tissue. The objectives of the present study were to detect dysregulated circRNAs from both tissue and plasma of patients with gastric cancer and to explore their potential roles in the pathogenesis of gastric cancer. Expression profiles of circRNAs were obtained from the Gene Expression Omnibus (GEO) and analyzed using the GEO2R tool to identify differential expressed circRNAs. The significance threshold was set as |log2 (fold change)| > 2 and adjusted P < .05. The microRNA (miRNA) binding sites of the differentially expressed circRNAs were predicted using the Circular RNA Interactome web tool. TargetScan and the miRNet database were used to predict the miRNA target genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed using Database for Annotation Visualization and Integrated Discovery. Hub genes were identified and a network was constructed with Cytoscape. The overall survival rates for the selected miRNAs and messenger RNAs were evaluated by Kaplan-Meier Plotter. A total of three downregulated circRNAs (hsa_circ_0001190, hsa_circ_0036287, and hsa_circ_0048607) were identified in this study. Six miRNAs and eight hub genes met the significance criteria and were selected for further analysis. A circRNA-miRNA-hub gene network was constructed based on three circRNAs, six miRNAs, and eight hub genes. Evaluation of overall survival rates for the hub genes showed that low expression levels of GADD45A, PPP1CB, PJA2, and KLF2 were associated with poor overall survival. This study identified potential novel plasma circRNA biomarkers and provides insights into the underlying mechanisms of gastric cancer pathogenesis.

6.
Environ Sci Technol ; 54(3): 1668-1676, 2020 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-31935071

RESUMO

The freezing-induced acceleration of bromate reduction by humic substances (HS) contributes to HS bromination and the formation of organobromine compounds (OBCs). Herein, we report the enhanced reduction of bromate by dissolved organic matter and the formation of large amounts of OBCs in freezing solutions. After 48 h of freezing process, 78.1-100% of bromate was reduced by DOM at different initial concentrations of bromate and DOM in acidic solutions (pH 3 and 4). Bromide was one of the main reduction products, and it accounted for 30.9-47.8% of the total bromine content. Except for bromide, a large amount of OBCs formed by brominating DOM with reactive bromine species, like hypobromite, were detected. The conversion of bromate to OBCs, calculated as the total organobromine content to the initial bromate content, ranged from 28.2 to 52.5% and was mainly dependent on the bromate/DOM content. About 110-603 species of OBCs were detected by Fourier transform ion cyclotron resonance mass spectrometry, and they were primarily highly unsaturated and phenolic compounds. By analyzing the spectral variation before and after the freezing process, we found the disappearance of 900 compounds containing only C, H, and O with a low carbon oxidation state that was regarded as the main reductant of bromate. Our findings call for further investigation of the processes and the effects of bromate formation in aqueous environments.


Assuntos
Bromatos , Substâncias Húmicas , Brometos , Congelamento , Halogenação
7.
Anal Chem ; 92(1): 1549-1556, 2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31823604

RESUMO

The photostability of graphene oxide (GO) strongly affects the performance of its products in optics and photonics. However, the photostability of GO, especially at trace levels, remains largely unexplored mainly because of the lack of available techniques. Herein, we developed a novel online system consisting of a highly efficient photoinduced chemical vapor generation reactor and an in situ measurement technique using a miniaturized and sensitive point discharge optical emission spectrometer. On the basis of the results of inorganic carbon species, abundant oxygen-containing functional groups on GO nanosheets made the degradation much easier than graphene. Under the optimized conditions (e.g., initial pH of 2.8 and binary photocatalysts dose of 200 mM H2O2, 1.0 mM Fe3+ ions, and 50 mg/L TiO2 NPs), the limit of detection for GO was 87.5 µg/L C with a linear range of 0.5-10 mg/L C. Specifically, the accuracy and reliability of the developed system was verified by quantifying self-prepared GO as well as aggregated GO in natural organic matter-rich water samples. Finally, the sunlight-induced photodegradation of GO under simulated environmental conditions was successfully tracked. The developed system is a promising platform for in-time quality control of GO-based products as well as predicting the occurrence, transformation, and fate of GO at environmentally relevant concentrations in the natural aquatic environment.

8.
Environ Sci Technol ; 53(23): 13802-13811, 2019 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-31697066

RESUMO

Freezing is essential in the light-mediated transformation of organic pollutants. However, the effects of the freezing process on the reduction of Ag+ by natural organic matter (NOM) remains unclear, causing significant uncertainties in the natural formation of silver nanoparticles (AgNPs). This study investigated the sunlight-induced reduction of Ag+ by NOM under natural or controlled freezing processes. Natural (outdoor) freezing experiments demonstrated intense aggregation and precipitation of AgNPs in three aqueous media, including a NOM solution and two river water samples, under natural sunlight irradiation. Indoor experiments under simulated sunlight irradiation and controlled freezing processes showed that freezing at -20 °C and repeated freeze-thaw cycles (-20 to 4 °C) drastically accelerated the formation and growth of AgNPs compared to maintenance at 4 °C. Finally, under the natural freezing process, commercial AgNPs were found to influence the redox reduction of Ag+ probably through a reduction in dissolution rates and homoaggregation with AgNPs newly formed in the river water samples. Additionally, the enhancement effect of freezing on AgNP formation was confirmed in the presence of Ag+ and AgNPs both at environmentally relevant concentration levels, especially upon light irradiation. This work emphasizes the importance of freezing processes on the natural formation of AgNPs.


Assuntos
Nanopartículas Metálicas , Prata , Congelamento , Oxirredução , Luz Solar
9.
Ann Transl Med ; 7(18): 466, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31700902

RESUMO

Background: Hepcidin and growth differentiation factor 15 (GDF-15) have been reported to be highly expressed in various cancers. Serum hepcidin and GDF-15 levels were demonstrated to be potential prognostic markers in cancers. This study aims to evaluate the effect of red blood cell (RBC) transfusion on plasma hepcidin and GDF-15 in gastric cancer patients. Methods: In this prospective study, 40 patients with gastric cancer were eligible for this study. Peripheral blood samples were obtained before and within 24 h after RBC transfusion. A routine blood test was performed before transfusion and within 24 h post-transfusion. Plasma hepcidin, GDF-15, interleukin 6 (IL-6) and erythropoietin were determined by ELISA. Results: In patients with metastasis, plasma hepcidin (P=0.02), and GDF-15 (P=0.01) levels were higher than without metastasis. Plasma hepcidin was increased after RBC transfusion (P=0.001), while plasma erythropoietin was decreased after transfusion (P=0.03). However, RBC transfusion did not affect plasma GDF-15 (P=0.32) and IL-6 (P=0.12). The effect of RBC transfusion on variables did not differ between metastatic and non-metastatic patients. The mean percentage change of hepcidin in transfusion volume 4 unit (U) was more than 2 U. Conclusions: RBC transfusion could increase plasma hepcidin and have no effect on plasma GDF-15 in gastric patients.

10.
Sci Total Environ ; 694: 133778, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31756817

RESUMO

Extracellular polymeric substance (EPS) secreted by microbes can interact with nanoparticles (NPs) and thus influence environmental behavior and toxicity of NPs. The adsorption of EPSs from two species of microbes (Escherichia coli and Chlorella pyrenoidosa) by four types of titanium dioxide nanoparticles (nTiO2) (5, 10, and 40 nm anatase nTiO2 and 25 nm rutile nTiO2) were therefore specifically investigated. Results show that the adsorption kinetics and thermodynamics were dependent on sources and chemical properties of EPSs. EPS (20 mg C/L) from Escherichia coli mainly composed of protein (86%) with relatively higher molecular weight and aromaticity and more active functional groups (i.e., NH and -COOH) was effectively removed (>90%) by adsorption on nTiO2 (100 mg and more), while much less (<40%) EPS from Chlorella pyrenoidosa with a main component of polysaccharide (68%) was adsorptively removed. The Fourier transform ion cyclotron resonance mass spectrometry analysis revealed the selective adsorption of aromatic components of EPSs by nTiO2. The EPS adsorption capacity of nTiO2 linearly increased with the specific surface area of the NPs. The rutile nTiO2 with the smallest specific surface area had the highest EPS adsorption per unit surface area. These findings promote a deeper understanding of the interaction between EPS and NPs.


Assuntos
Matriz Extracelular de Substâncias Poliméricas/química , Nanopartículas/química , Titânio/química , Adsorção , Chlorella
11.
Environ Pollut ; 255(Pt 2): 113302, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31597113

RESUMO

The intentional production and degradation of plastic debris may result in the formation of nanoplastics. Currently, the scarce information on the environmental behaviors of nanoplastics hinders accurate assessment of their potential risks. Herein, the aggregation kinetics of different surface-modified polystyrene nanoparticles in monovalent and divalent electrolytes was investigated to shed some light on the fate of nanoplastics in the aquatic environment. Three monodisperse nanoparticles including unmodified nanoparticles (PS-Bare), carboxylated nanoparticles (PS-COOH) and amino modified nanoparticles (PS-NH2), as well as one polydisperse nanoparticles that formed by laser ablation of polystyrene films (PS-Laser) were used as models to understand the effects of surface groups and morphology. Results showed that aggregation kinetics of negatively charged PS-Bare and PS-COOH obeyed the DLVO theory in NaCl and CaCl2 solutions. The presence of Suwannee river natural organic matters (SRNOM) suppressed the aggregation of PS-Bare and PS-COOH in monovalent electrolytes by steric hindrance. However, in divalent electrolytes, their stability was enhanced at low concentrations of SRNOM (below 5 mg C L-1), while became worse at high concentrations of SRNOM (above 5 mg C L-1) due to the interparticle bridging effect caused by Ca2+ and carboxyl groups of SRNOM. The cation bridging effect was also observed for PS-laser in the presence of high concentrations of divalent electrolytes and SRNOM. The adsorption of SRNOM could neutralize or even reverse surface charges of positively charged PS-NH2 at high concentrations, thus enhanced or inhibited the aggregation of PS-NH2. No synergistic effect of Ca2+ and SRNOM was observed on the aggregation of PS-NH2, probably due to the steric repulsion imparted by the surface modification. Our results highlight that surface charge and surface modification significantly influence aggregation behaviors of nanoplastics in aquatic systems.


Assuntos
Eletrólitos/química , Nanopartículas/química , Poliestirenos/química , Adsorção , Cátions , Concentração de Íons de Hidrogênio , Cinética , Modelos Químicos , Plásticos , Rios , Cloreto de Sódio
12.
Anal Chem ; 91(19): 12525-12530, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31495175

RESUMO

A new method was developed to determine the nanoparticulate and ionic silver (Ag) species in bacteria (Escherichia coli, E. coli). By removal of the cell wall with lysozyme, the cell surface-adsorbed Ag species were separated from the intracellular Ag species, which were extracted by tetramethylammonium hydroxide and determined by size-exclusion chromatography coupled with inductively coupled plasma mass spectrometry (SEC-ICP-MS). The detection limit is 3 ng/107 CFU/mL (where CFU is colony-forming unit) for both silver nanoparticles (AgNPs) and ionic Ag(I) species. The cell wall-adsorbed Ag was calculated by subtracting the contents of the intra- and extracellular Ag from the total exposure dose of Ag, and therefore the biodistribution of Ag species was profiled. We then applied this strategy to quantitatively analyze extra- and intracellular Ag species in E. coli after respective exposure to Ag+ and 10 and 30 nm AgNPs at different effective concentrations (EC10, EC50, and EC90). Results showed that the intracellular and cell wall-bound Ag account for 5.98-15.21% and 25.13-64.43% of the exposed dose, respectively, and AgNPs could transform into complexed or free Ag+. Our method opens new avenues for the quantitative analysis of the uptake and biodistribution of nanoparticles and their transformation species in bacteria.

13.
Environ Sci Technol ; 53(17): 10218-10226, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31380632

RESUMO

To track transformations of silver nanoparticles (AgNPs) in vivo, HepG2 and A549 cells were cocultured with two enriched stable Ag isotopes (107AgNPs and 109AgNO3) at nontoxic doses. After enzymatic digestion, 107AgNPs, ionic 107Ag+ and 109Ag+ in exposed cells could be separated and quantified by liquid chromatography combined with ICP-MS. We found that ratios of 107Ag+ to total 107Ag and proportions of 107Ag+/ 109Ag+ in cells increased gradually after exposure, proving that the Trojan-horse mechanism occurred, i.e., AgNPs released high contents of Ag+ after internalization. While the presence of 109Ag+ (5 and 100 µg/L) has little influence on the uptake of 107AgNPs (0.1 and 2 mg/L), the presence of 107AgNPs at a high dose (2 mg/L) dramatically increases the ingestion of 109Ag+, even though 107AgNPs at a low dose (100 µg/L) showed negligible effects on the internalization of 109Ag+. Cellular homeostasis may be perturbed under sublethal exposure of 107AgNPs, and thus enhanced uptake of 109Ag+. Our findings suggest that the widely adopted control experiments in toxicology studies, culturing organisms with AgNO3 at the same concentration of Ag+ in the AgNP exposure medium, may underestimate uptake of Ag+ and thus cannot exclude suspected toxic effects of Ag+ at high AgNP exposure doses.


Assuntos
Nanopartículas Metálicas , Prata , Íons , Isótopos , Solubilidade
14.
Environ Pollut ; 252(Pt B): 1574-1581, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31277026

RESUMO

The bioavailability of a pollutant is usually evaluated based on its freely dissolved concentration (Cfree), which can be measured by negligible-depletion equilibrium extraction that is commonly suffered from long equilibration time. Herein, metal-organic framework (MOF) composites (Fe3O4@MIL-101), consists of a magnetic Fe3O4 core and a MIL-101 (Cr) MOF shell, is developed as sorbents for negligible-depletion magnetic solid-phase extraction (nd-MSPE) of freely dissolved polyaromatic hydrocarbons (PAHs) in environmental waters. The freely dissolved PAHs in 1000 mL water samples are extracted with 1.5 mg MOF composites, and desorbed with 0.9 mL of acetonitrile under sonication for 5 min. The MOF composites exclude the extraction of dissolved organic matter (DOM) and DOM-associated PAHs by size exclusion. Additionally, the combined interactions (hydrophobic, π-π and π-complexation) between PAHs and composites markedly reduced the extraction equilibration time to < 60 min for all the studied PAHs with logKOW up to 5.74. Moreover, the porous coordination polymers property of the MOFs makes the proposed nd-MSPE based on the partitioning of PAHs and thus excludes the competitive adsorption of coexisting substances. The developed nd-MSPE approach provides low detection limits (0.08-0.82 ng L-1), wide linear range (1-1000 ng L-1) and high precision (relative standard deviations (RSDs) (3.3-4.8%) in determining Cfree of PAHs. The measured Cfree of PAHs in environmental waters are in good agreement with that of verified method. Given the large diversity in structure and pore size of MOFs, various magnetic MOFs can be fabricated for task-specific nd-MSPE of analytes, presenting a prospective strategy for high-efficiency measuring Cfree of contaminants in environments.


Assuntos
Nanopartículas de Magnetita/química , Estruturas Metalorgânicas/química , Nanocompostos/química , Hidrocarbonetos Policíclicos Aromáticos/análise , Extração em Fase Sólida/métodos , Poluentes Químicos da Água/análise , Adsorção , Interações Hidrofóbicas e Hidrofílicas , Limite de Detecção , Solubilidade
15.
Talanta ; 200: 357-365, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31036196

RESUMO

There are few studies on separation and size characterization of zinc oxide nanoparticles (ZnO-NPs), which have wide applications in several science and technology areas, in the environment. In this work, we report a method for the separation and size characterization of ZnO-NPs by asymmetrical flow field-flow fractionation (AF4) coupled to UV-vis detector. Experimental conditions such as composition of the carrier solution, focus time, crossflow, detector flow rate and injection volume were systematically studied in terms of NPs separation, recovery, and repeatability. Size characterization was achieved using polystyrene nanoparticles as a size standard and a mixture of < 35 nm (NP-A) and < 100 nm (NP-B) ZnO-NPs were separated and size characterized posterior preconcentration using ultracentrifugation. The method was also employed to characterize the size of homemade ZnO-NPs, and the results were in concordance with dynamic light scattering (DLS) analysis and thus, the method can be used as an alternate method. Upon application on environmental water samples, the two ZnO-NPs, NP-A and NP-B, have been separated and size characterized. The estimated hydrodynamic sizes of the NP-A and NP-B were found to be in the range of 83-97 nm and 188-202 nm, respectively, with good precision (RSD, <11%), suggesting that the current method can satisfactorily separate and generate information about sizes of the NPs in samples with a complex matrix. Therefore, the developed technique can be used as a baseline to investigate size related environmental processes of the NPs in environmental water samples.

16.
Water Res ; 157: 472-482, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30981978

RESUMO

As one of the key economic modes in China, chemical industry park (CIP) has made great contribution to the Chinese rapid economic growth. Concomitantly, how to effectively and safely dispose of the CIP wastewater (CIPWW) has been an unavoidable issue. Molecular transformation of dissolved organic matter (DOM) in CIPWW treatment is essential to optimize the employed process and to provide solid basis for risk evaluation of the discharged effluent as well. In this study, electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) was used to characterize the molecular transformation of DOM during full-scale treatment of integrated chemical wastewater in a centralized wastewater treatment plant (CWWTP), where the combined process follows hydrolysis/acidification (HA)-flocculation/precipitation (FP)-A2/O-membrane bioreactor (MBR)-ultrafiltration (UF)-reverse osmosis (RO). Compared to municipal wastewater, DOM in CIPWW exhibited higher unsaturation degree, lower molecular weight, and higher toxicity. In FP unit, DOM of C<24 and higher nominal oxidation state of carbon (NOSC) values was preferentially removed. The HA and anaerobic units are capable of significantly degrading DOM, resulting in great changes in molecular composition of DOM. However, the anoxic, oxic, and MBR units only lead to a slight change of the molecular formulae. The terminal units of UF and RO can remove most DOM, with the concentration of dissolved organic carbon (DOC) declining by 19.2% and 94.6% respectively. The correlation between spectral indexes and acute toxicity with the molecular formulae of DOM suggested that polyphenols and highly unsaturated phenols were positively correlated with the specific UV absorbance at 254 nm (SUVA254). In addition, both compounds (0.32 < O/C < 0.63) as well as the aliphatic ones (0.22 < O/C < 0.56) presented positive correlation with acute toxicity. Further, the pairwise correlation analysis illustrated that SUVA254, O/Cwa, double bond equivalence (DBEwa), and NOSCwa were positively correlated with each other, whereas the acute toxicity was positively correlated with humification index (HIX), O/Cwa, and DBEwa.


Assuntos
Ultrafiltração , Águas Residuárias , China , Filtração , Espectrometria de Massas
17.
J Environ Sci (China) ; 78: 109-117, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30665629

RESUMO

Biochar is extensively used as an effective soil amendment for environmental remediation. In addition to its strong contaminant sorption capability, biochar also plays an important role in chemical transformation of contaminant due to its inherent redox-active moieties. However, the transformation efficiency of inorganic contaminants is generally very limited when the direct adsorption of contaminants on biochar is inefficient. The present study demonstrates the role of Fe ion as an electron shuttle to enhance Cr(VI) reduction by biochars. Batch experiments were conducted to examine the effects of Fe(III) levels, pyrolysis temperature of biochar, initial solution pH, and biochar dosage on the efficiency of Cr(VI) removal. Results showed a significant enhancement in Cr(VI) reduction with an increase in Fe(III) concentration and a decrease of initial pH. Biochar produced at higher pyrolysis temperatures (e.g., 700°C) favored Cr(VI) removal, especially in the presence of Fe(III), while a higher biochar dosage proved unfavorable likely due to the agglomeration or precipitation of biochar. Speciation analysis of Fe and Cr elements on the surface of biochar and in the solution further confirmed the role of Fe ion as an electron shuttle between biochar and Cr(VI). The present findings provide a potential strategy for the advanced treatment of Cr(VI) at low concentrations as well as an insight into the environmental fate of Cr(VI) and other micro-pollutants in soil or aqueous compartments containing Fe and natural or engineered carbonaceous materials.


Assuntos
Carvão Vegetal/química , Cromo/química , Recuperação e Remediação Ambiental/métodos , Poluentes do Solo/química , Elétrons , Compostos Férricos/química
18.
Environ Sci Technol ; 53(2): 625-633, 2019 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-30525513

RESUMO

Knowledge on the uptake and transformation of silver nanoparticles (AgNPs) and Ag+ ions by organisms is critical for understanding their toxicity. Herein, the differential uptake, transformation, and translocation of AgNPs and Ag+ ions in hydroponic rice ( Oryza sativa L.) is assessed in modified Hewitt (with Cl- ions, HS(Cl)) and Hogland solutions (without Cl- ions, HS) using dual stable isotope tracing (107AgNO3 and 109AgNPs). After coexposure to 107Ag+ ions and 109AgNPs at 50 µg L-1 (as Ag for both) for 14 days, a stimulatory effect was observed on root elongation (increased by 68.8 and 71.9% for HS(Cl) and HS, respectively). Most of the Ag+ ions (from 107Ag+ ions and 109AgNPs) were retained on the root surface, while the occurrence of AgNPs (from 109AgNPs and 107Ag+ ions) was observed in the root, suggesting the direct uptake of AgNPs and/or reduction of Ag+ ions. Higher fractions of Ag+ ions in the shoot suggest an in vivo oxidation of AgNPs. These results demonstrated the intertransformation between Ag+ ions and AgNPs and the role of AgNPs as carriers and sources of Ag+ ions in organisms, which is helpful for understanding the fate and toxicology of Ag.


Assuntos
Nanopartículas Metálicas , Oryza , Íons , Isótopos , Prata
19.
Anal Chem ; 91(3): 1785-1790, 2019 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-30588801

RESUMO

The contamination of micro- and nanoplastics in marine systems and freshwater is a global issue. Determination of micro- and nanoplastics in the aqueous environment is of high priority to fully assess the risk that plastic particles will pose. Although microplastics have been detected in a variety of aquatic ecosystems, the analysis of nanoplastics remains an unsolved challenge. Herein, for the first time, a Triton X-45 (TX-45)-based cloud-point extraction (CPE) was proposed to preconcentrate trace nanoplastics in environmental waters. Under the optimum extraction conditions, an enrichment factor of 500 was obtained for two types of nanoplastics with different compositions, polystyrene (PS) and poly(methyl methacrylate) (PMMA), without disturbing their original morphology and sizes. Additionally, following thermal treatment at 190 °C for 3 h, the CPE-obtained extract could be submitted to pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) analysis for mass quantification of nanoplastics. Taking 66.2 nm PS nanoplastics and 86.2 nm PMMA nanoplastics as examples, the proposed method showed excellent reproducibility, and high sensitivity with respective detection limits of 11.5 and 2.5 fM. Feasibility of the proposed approach was verified by application of the optimized procedure to four real water samples. Recoveries of 84.6-96.6% at a spiked level of 88.6 fM for PS nanoplastics and 76.5-96.6% at a spiked level of 50.4 fM for PMMA nanoplastics were obtained. Consequently, this work provides an efficient approach for nanoplastic analysis in environmental waters.

20.
Environ Pollut ; 246: 1-10, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30529933

RESUMO

Aluminum dialkyl phosphinates (ADPs) are a class of promising phosphorus-containing flame retardants, but their environmental fate is not well understood. Sorption and transport behaviors of ADPs, and their hydrolysates dialkyl phosphinic acids (DPAs) were studied by batch and column experiments. ADPs are less mobile in soil columns with more than half (>52.6%) of ADPs retained in the soil and residues in the topmost 2-cm layer account for more than 57% of total residues. Dissolution and dispersion of fine grain ADPs were responsible for the transport of ADPs. Sorption DPAs (logKoc) was significantly related to the lipophilicity of DPAs (logD) (p < 0.05). Soil pH and clay content were the dominant factors governing the sorption and transport of DPAs in soils, indicating the importance of electrostatic interactions. The retardation factors (R) of DPAs derived from leaching experiments were pH-dependent with larger R values in the acidic soil (pH = 4.0) where anionic and neutral species of DPAs coexisted. Both physical and chemical non-equilibrium convection-dispersion equations (CDE) yield appropriate modeling for DPAs transport. In most cases, R values estimated from column tests differed from those derived from the batch experiments, which might be attributed to non-equilibrium sorption processes in dynamic conditions.


Assuntos
Alumínio/química , Retardadores de Chama , Ácidos Fosfínicos/química , Poluentes do Solo/química , Solo/química , Adsorção , Monitoramento Ambiental , Modelos Teóricos , Solubilidade
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