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As persistent organic pollutants (POPs) newly banned by the Stockholm Convention, polychlorinated naphthalenes (PCNs) have been widely detected in various environmental matrices. To date, however, the occurrence of PCNs in soils and plants in the Arctic environment has not been reported. In the current study, the concentrations and distribution of PCNs in Arctic soils and plants from Svalbard were analyzed. Total PCN concentrations ranged from 5.3 to 2550 pg/g dry weight (dw) in soils and 77 to 870 pg/g dw in plants. The higher levels of PCNs near the research stations and Longyearbyen town highlighted the significant influence of local anthropogenic emission sources. The composition of PCNs in Arctic soils and plants was dominated by lower chlorinated homologues, especially mono- to trichlorinated naphthalenes, which accounted for over 80 % of total PCNs in the soil and plant samples. The correlation analysis indicated the potential influences of total organic carbon (TOC) content on PCN concentrations in the soil, and octanol-air partition coefficients (K

Contaminants in high-altitude mountains such as the Tibetan Plateau (TP) have attracted extensive attention due to their potential impact on fragile ecosystems. Rapid development of the economy and society has promoted pollution caused by local traffic emissions in the TP. Among the pollutants emitted by traffic, polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (OPAHs) are of particular concern due to their high toxicity. The TP provides an environment to explore the degree and range of contribution for traffic-induced PAHs and OPAHs. In this study, soils and moss were collected at different altitudes and distances from the G318 highway in the southeast TP. The total concentrations of PAHs (∑

To evaluate the synergetic adsorption capacity of layered double hydroxide (LDH) and photocatalytic reduction property of TiO2 for aqueous Cr(VI), the Fe3O4-ZnAl-LDH and TiO2 composites (FLT) were prepared via sol-gel method. The removal efficiency of FLT composites for Cr(VI) changed with the mass ratio of Fe3O4-LDH/TiO2, and the optimal ratio was 20% (FLT-2). The adsorption efficiencies of 100 mg FLT-2 were 74% and 64% for 20 and 50 mg/L Cr(VI) solution, and the total removal ratios of Cr(VI) were all over 97% after UV irradiation. The experimental data of adsorption kinetic, adsorption isothermal, and photocatalytic reduction were consistent with the pseudo-second-order, Langmuir, and first-order reaction equations, respectively. From the X–ray photoelectron spectra analysis, FLT composites adsorbed Cr(VI) directly via surface complexation, also reduced aqueous Cr(VI) to Cr(III). The photocurrent and electrochemical impedance spectroscopy of FLT composites indicated the photo-induced electron-hole pairs were separated effectively. The regeneration results show that the FLT composites had good stability and reusability after five consecutive cycles. Therefore, FLT composites are promising materials in the disposal of wastewater containing Cr(VI).

Per-and polyfluoroalkyl substances (PFASs) are omnipresent globally and received increasing attention recently. However, there are limited data on PFASs in the Tibetan Plateau (TP), a remote high-altitude mountain region, which is regard as an important indicator region to study long-range transport behaviors of contaminants. This study investigates the occurrence, distribution, partitioning behavior, and sources of 26 PFASs in water and sediments from the four lakes of TP. The ΣPFAS concentrations ranged from 338 to 9766 pg Lsup-1/supin water, and 12.2-414 pg gsup-1/supdry weight in sediments. Perfluorobutanonic acid (PFBA) and perfluorooctane sulfonate (PFOS) were detected in all samples. Qinghai Lake had the highest ΣPFAS concentrations in both water and sediments, while the Ranwu Lake had the lowest. The functional groups and CFsub2/submoiety units were investigated as essential factors influencing the partition behavior. Principal component analysis (PCA) combined back-trajectory was used to infer possible sources of PFASs. The results suggested that the main source of PFASs in Yamdrok Lake, Namco Lake, and Ranwu Lake on southern TP were mainly originated from South Asia via long-range atmospheric transport (LRAT); while for the Qinghai Lake of northern TP, LRAT, local emissions, and tourism activities were the primary sources of PFASs.

Black carbon (BC) is released into the atmosphere in large quantities from different emission sources each year and poses a serious threat to human health. These BC possessed a variety of characteristics and different mediation abilities for the reactive oxygen species (ROS) generation. In this study, we collected BC (i.e., diesel BC, coal BC and wood BC) from three typica emission sources, and examined their mediation abilities to the oxidation of glutathione (GSH). Results showed that all three BC significantly promoted the GSH oxidation, and the mediation efficiencies were as follows: diesel BC coal BC wood BC. In comparison with the water-soluble fraction, the mediation abilities of three BC mainly came from their solid phase fractions. In the coal BC and wood BC systems, the oxidation of GSH was attributed to the catalysis of transition metals in BC. By contrast, the transition metals, phenolic -OH and persistent free radicals in diesel BC were identified as the active sites responsible for the GSH oxidation. In addition, the graphitic surface of diesel BC could synergize with these active sites to accelerate the oxidation of GSH. Under the catalysis of BC, dissolved oxygen was first reduced to ROS (O

Concentrations of polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFRs) in the atmosphere of Ny-Ålesund, Svalbard, were investigated. Passive air samples were collected for eight consecutive one-year periods from August 2011 to August 2019 at seven Arctic sampling sites. High-resolution gas chromatography coupled with high-resolution mass spectrometry (HRGC-HRMS) and gas chromatography coupled with election capture negative ionization mass spectrometry (GC-NCI-MS) were employed for PBDE and NBFR analysis, respectively. The median concentrations of Ʃ

Novel flame retardants (FRs) are of increasing concern, given growing evidence of health effects and use to replace polybrominated diphenyl ethers (PBDEs). This study modeled combined effects of use policies and decoration on indoor FRs and human exposure for 18 widely used PBDEs, organophosphate esters (OPEs), and novel brominated flame retardants in typical urban indoor environments in China. The current estimated indoor emission rates and average concentrations in air and dust of the 18 FRs were 102-103 ng/h, 561 ng/m3, and 1.5 × 104 ng/g, respectively, with seven OPEs dominant (>69%). Different use patterns exist between China and the US and Europe. Scenarios modeled over 2010-2030 suggested that decoration would affect indoor concentrations of FRs more than use policies, and use policies were mainly responsible for shifts of FR composition. Additional use of hexabromobenzene and 2,3,4,5,6-pentabromotoluene and removal of BDE-209 would make the total human exposure to the modeled FR mixture increase after the restriction of penta- and octa-BDE but decrease after deca-BDE was banned. Better knowledge of the toxicity of substitutes is needed for a complete understanding of the health implications of such changes. Toddlers may be more affected by use changes than adults. Such studies are supportive to the management of FR use.

Novel brominated flame retardants (NBFRs) and organophosphate esters (OPEs) have been widely detected in various environmental matrices worldwide and raised public concerns in recent years. However, few studies reported their occurrence and temporal trend in Antarctic air. In this study, concentrations, distribution, and temporal trends of NBFRs and OPEs in the air of Fildes Peninsula, West Antarctica, were investigated using XAD resin-based passive air sampling from January 2011 to January 2020. Air concentrations of the total OPEs (Σ

Reduced graphene oxide (rGO) is one of the most widely used carbon nanomaterials. When it is released into the environment, rGO can markedly affect the transformation of many pollutants, and change their fate and risk. In this work, the synergetic effects of rGO and Cu(II) on the oxidation of 2-naphthol were examined in water in the dark. It was found that the coexistence of rGO and Cu(II) significantly promoted the oxidation of 2-naphthol. Corresponding products were identified as the coupling oligomers of 2-naphthol (dimer, trimer and tetramer) and hydroxylated compounds (OH-2-naphthol, OH-dimer, di–OH–dimer and naphthoquinone derivatives). In the oxidation reaction, rGO played dual roles, i.e. adsorbent and electron-transfer mediator. rGO firstly adsorbed Cu(II) and 2-naphthol on its surface, and then transferred electrons from 2-naphthol to Cu(II) to yield 2-naphthol radicals and Cu(I). 2-Naphthol radicals coupled to each other to form different oligomers of 2-naphthol. Cu(I) was re-oxidized back to Cu(II) by dissolved oxygen, which sustained the continuous oxidation of 2-naphthol. During the autoxidation of Cu(I), reactive oxygen species were generated, which further reacted with 2-naphthol to form hydroxylated products. These findings provide new insights into the risk assessment of rGO and 2-naphthol in aquatic environments.

In this work, the magnetic alginate microsphere of Fe3O4/MgAl-LDH (Fe3O4/LDH-AM) was prepared by immobilizing the Fe3O4/LDH with calcium alginate (CA) and was used to remove Cd2+, Pb2+, and Cu2+ from aqueous solutions. The obtained Fe3O4/LDH-AM was characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller surface area determination. The results indicated that the surface groups of the alginate and LDH were retained and so was the crystal structure in the alginate microsphere. The adsorption performance of the Fe3O4/LDH-AM for Cd2+, Pb2+, and Cu2+ in aqueous solutions was evaluated by batch and column adsorption experiments. The effects of adsorption conditions, kinetics, isotherms, mechanisms, and potential applications were investigated. The adsorption kinetic data conformed to the pseudo-second-order kinetic equation, and the isotherm data fit well with the Freundlich and Langmuir isotherm models. The adsorption mechanism of Cd2+, Pb2+, and Cu2+ by the Fe3O4/LDH-AM entailed complexation and precipitation. The experimental breakthrough curves were correlated with the Thomas model. Moreover, the Fe3O4/LDH-AM displayed superior regeneration and reusability. These results suggest that the Fe3O4/LDH-AM is an efficient adsorbent for the removal of heavy metals and can be effectively employed in practical applications.

An environmentally friendly and efficient catalyst is important for the persulfate activation and pollutants removal from water. In this study, nano-graphite (NG) prepared by detonation method, was firstly applied as the superb carbon catalyst to activate peroxydisulfate (PDS) for the degradation of bisphenol S (BPS) via a non-radical pathway. Results showed that NG had a very high catalytic performance and degraded most of BPS within 20.0 min, out-performing many popular metal-based catalysts. The doped N atoms (i.e. graphitic N and pyridinic N) in NG were identified as the possible reactive sites for the PDS activation. It is proposed that PDS could form the metastable surface-bound PDS complexes on the NG surface, which promoted the BPS degradation. The NG/PDS system had a strong anti-interference ability for the environmental background substances and a wide operative pH range, so it had a good application prospect in the actual wastewater environment. This study not only provides an efficient method for the removal of bisphenol pollutants, but also deepens the insight into the reaction mechanisms.

Ionic antibiotics and metals generally coexist, and their interaction can affect their sorption behaviors onto soil minerals, therefore determining their environmental hazards. This study investigated the sorption and cosorption of Zn(II) and chlortetracycline (CTC) onto montmorillonite at different solution pH (3−10) using batch experiments and extended X-ray absorption fine structure (EXAFS) analysis. The Langmuir model could reproduce well the sorption isotherms of Zn(II) and CTC. The presence of CTC/Zn(II) could promote the maximum sorption capacity (Qm) of Zn(II)/CTC, based on site energy distribution (SED) theory. Generally, Zn(II) sorption increased with pH increasing. Comparatively, CTC sorption decreased as pH increased till approximately pH 5.0, then increased continuously with pH increasing. Both CTC and Zn(II) co-existence enhanced their individual sorption in both acidic and neutral environments. The processes behind CTC and Zn(II) sorption mainly included cation exchange and surface complexation. The EXAFS data evidenced that the presence of CTC could alter the species of Zn(II) on montmorillonite via surface complexation at pH 4.5 and 7.5, with Zn-CTC complexes being the predominant species on montmorillonite at pH 7.5. At pH 9.5, Zn(II) may exist onto montmorillonite in precipitated form similar to Zn-Al hydrotalcite-like compound (HTlc) regardless of CTC presence.

Terrestrial plants, which account for the world’s largest biomass and constitute the basis of most food webs, take up, transform, and accumulate organic chemical contaminants from the ambient environment. In this study, we determined the concentrations and congener profiles of polybrominated diphenyl ethers (PBDEs) and hydroxylated and methoxylated polybrominated diphenyl ethers (OH-PBDEs and MeO-PBDEs) in surface soil and vegetation samples collected from the Arctic (Svalbard) and Antarctica (King George Island) during the Chinese Scientific Research Expeditions. The concentrations of total PBDEs (∑PBDEs) in soil and vegetation samples collected from the Arctic (5.6–270 pg/g dry weight) were higher than those from Antarctica (2.3–33 pg/g dw), whereas the concentrations of ∑MeO-PBDEs and ∑OH-PBDEs were lower in Arctic terrestrial samples (n.d.–0.75 and 0.0008–1.1 ng/g dw, respectively) than in samples from Antarctica (0.007–4.0 and 0.034–25 ng/g dw, respectively). Long-range atmospheric transport and human activities were potential sources of PBDEs in polar regions, whereas the dominance of ortho-substituted MeO-PBDE and OH-PBDE congeners in terrestrial matrices indicated the importance of natural sources. To the best of our knowledge, this study represents the first report on the levels and behaviors of MeO-PBDEs and OH-PBDEs in terrestrial environment of polar regions.

The concentrations and distributions of nine novel brominated flame retardants (NBFRs) were analyzed in soil, lichen (Usnea aurantiaco-atra), and moss (Sanionia uncinata) samples collected from the Chinese Antarctic Great Wall Station and surrounding Fildes Peninsula area in west Antarctica. Total NBFR concentrations ranged from 61.2-225 pg/g dry weight (dw) in soil, 283-1065 pg/g dw in moss, and 135-401 pg/g dw in lichen, respectively. Decabromodiphenyl ethane (DBDPE) was the dominant NBFR in all samples, accounting for 65.2%, 50.1%, and 72.4% of cumulative NBFR concentration in soil, moss, and lichen, respectively. The concentrations of NBFRs in plant samples were higher than those in soil, which may be related to plant bioaccumulation. Significant log/log-linear correlations (p 0.05) were found between the concentrations of BEHTEBP and total organic carbon (TOC) in soil, and between DBDPE and lipid content in mosses, indicating that TOC and lipid content potentially affect certain NBFRs in Antarctic soil and moss. This study presents the first report on NBFR contamination in soil and various vegetation in Antarctica.

Black carbons (BCs) are ubiquitous in the natural environment and can significantly influence the environmental behavior of pollutants. This work examined the mediating effects of graphite, soot, and biochar on 1-naphthylamine (1-NA) oxidation under aerobic conditions. It was shown that the three BCs significantly promoted the oxidation of 1-NA in the dark, and the mediation efficiency of graphite was much greater than that of soot or biochar. The oxidation products were the coupling oligomers (dimers and trimers) and the oxygen-containing oligomers of 1-NA (di-OH-1-NA, OH-azo naphthalene, OH-trimers and amino-naphthoquinone derivatives etc.). The phenolic OH on BCs were identified as the active sites for 1-NA oxidation, which could stimulate O2 to produce reactive oxygen species through successive single electron transfer and then cause 1-NA oxidation. Moreover, the superior catalytic performance of graphite was also related to its high electrical conductivity. The synergies between the sp2-hybridized carbon surface and the active sites (such as phenolic OH and defects) facilitated the oxidation of 1-NA on graphite. Findings in this study not only are helpful for better understanding the reactivity of environmental BCs, but also provide new insights into the risk assessment of 1-NA in the natural environment.

Substituent effects of 4-nitrophenol (4-NP), phenol (PE), 4-methylpheol (4-MP), and 4-methoxyphenol (4-MOP) on their oxidative coupling reactions mediated by reduced graphene oxide (rGO) were examined using a batch method. The reaction products were identified as the oligomers of their individual parent compound, and C C and C O coupling between phenolic radicals were the main reaction pathways. The oxidative kinetics were well described with pseudo-first order model. The rate constants (kobs) of 4-NP, PE, 4-MP and 4-MOP were 0.47 × 10−3, 1.00 × 10−3, 2.03 × 10−3, and 3.53 × 10−3 h−1, respectively, following the order 4-NP H)), suggesting that BDE(O H) was an effective indicator to predict the oxidation susceptibility of phenolic compounds in rGO system. Dissolved oxygen played a critical role in the oxidation reactions through the formation of superoxide anion (O2 −) on rGO. These O2 − further cleaved the O H bond of phenolic compounds to produce phenolic radicals, which interacted each other and led to the following oxidative coupling reactions. The finding of this study is important for predicting the environmental fate of rGO and phenolic compounds.

Research on the environmental fate and behavior of novel brominated flame retardants (NBFRs) remains limited, especially in the remote alpine regions. In this study, the concentrations and distributions of NBFRs were investigated in soils and mosses collected from two slopes of Shergyla in the southeast of the Tibetan Plateau (TP), to unravel the environmental behaviors of NBFRs in this background area. The total NBFR concentrations (∑7NBFRs) ranged from 34.2 to 879 pg/g dw in soil and from 72.8 to 2505 pg/g dw in moss. ∑7NBFRs in soil samples collected in 2019 were significantly higher than those in 2012 (p

Three reduced graphene oxide (rGO) with different defect contents were prepared at 250, 600 and 1000 °C, respectively, using thermal reduction method, and their effects on the oxidative coupling processes of 4-methoxyphenol (MOP) in aqueous solution were investigated. In the presence of rGOs, the oxidation of MOP was dramatically accelerated. At the same surface area dose, the catalytic efficiencies of three rGOs followed an ascending order of rGO 250 ≤ rGO 600 1000 . Using liquid chromatography-mass spectrometry and molecular modeling computation, we identified the coupling products (dimer, trimer, and tetramer), and revealed that ortho C O and ortho-ortho C C coupling between two MOP radicals were the main reaction pathways. Dissolved oxygen and structural defects of rGOs played important roles in the oxidation of MOP. It is proposed that dissolved oxygen reacted with the defect sites of rGO to produce surface-bound superoxide species, which captured H atom from the phenolic hydroxyl group of MOP to generate MOP radical and H 2 O 2 . A portion of H 2 O 2 can be catalyzed further by rGO to hydroxyl radical, which continued to react with MOP to produce MOP radical and H 2 O.

To evaluate the synergetic adsorption capacity of layered double hydroxide (LDH) and photocatalytic reduction property of TiO

A compact driver based on current feedback amplifiers is designed to drive interdigital transducers (IDTs) that generate standing surface acoustic waves for cell sorting. Compared with commercial RF amplifiers, this driver can be used to drive a wider range of loads without impedance matching. Furthermore, the driver works in a switch mode triggered by target cells, which significantly reduces power consumption in the system. A Butterworth-Van Dyke equivalent circuit was fabricated to study the electrical characteristics of the IDTs, and the driver was designed and optimized by circuit simulations. A cell sorter was constructed and tested experimentally to demonstrate that the driver meets sorting requirements. The driver allows the cell sorter to extract rare cells while otherwise consuming low power.

The adsorption behavior of bisphenol S (BPS) on reduced graphene oxide (rGO) was investigated. The adsorption kinetics data are best described with a pseudo-second-order model and the equilibrium data are well fitted by both Freundlich and Langmuir models. The maximum adsorption capacity of BPS on rGO at pH 6.0 and T = 298 K was 261.74 mg g−1. It was found that the increase of solution pH was unfavorable for BPS adsorption due to the increasing electrostatic repulsion between BPS and rGO. The thermodynamics data indicated that the adsorption of BPS on rGO was a spontaneous and exothermic process. Fourier transform infrared (FTIR) spectra suggested that BPS adsorption on rGO was primarily driven by π–π interaction between the graphene's hexagonal arrays and the aromatic core of BPS. Results from this study demonstrate that rGO is a promising adsorbent for BPS removal in water treatment.

In this work, the magnetic alginate microsphere of Fe

The mediation effect of reduced graphene oxide (rGO) on the oxidative transformation of 1,4-hydroquinone (H(2)Q) to 1,4-benzoquinone (BQ) in aqueous solution was investigated using a batch method and electron paramagnetic resonance. The results showed that the autoxidation of H(2)Q was spin-restricted and extremely slow in acidic and neutral pH range, but this process can be dramatically accelerated when rGO was added. In the presence of 33.3 mg L-1 rGO, more than 76.0% of H(2)Q was oxidized to BQ within 36 h. The enhancement effects of rGO were attributed to the combined contribution of the high chemical reactivity of graphenic edges and defects on rGO and the high electron conductivity of graphene basal surface of rGO. It is proposed that dissolved oxygen reacted with graphenic edges and defects of rGO to produce surface-bound oxygen intermediates, which capture H atoms from the phenolic hydroxyl groups of H(2)Q and facilitate the generation of semiquinone radical (SQ(center dot-)). The generated SQ(center dot-) continued to transfer an electron to molecular oxygen to yield superoxide radical (OF) and BQ. As a chain-carrying radical, OF further reacted with H(2)Q to produce SQ(center dot-) and H2O2. (C) 2015 Elsevier Ltd. All rights reserved.

A modified target field method is presented to the construction of shim and gradient coils for Halbach-type magnet featuring cylindrical magnet and transversal magnetic field direction. With Biot–Savart law, magnetic field is deduced from current density distribution, and two solutions corresponding to relations between spherical harmonic functions degree m and current density degree k, namely $$m=k\pm 1$$ are derived. Then combined with magnetic field distribution of target points, current density coefficient $$U_{\rm q}$$ is adopted to calculate stream function, based on which the coils' structure can be obtained. An appropriate objective function integrating dissipated energy and relative error is utilized to further improve the design. Examples of X2–Y2 and Y coils indicate that solution corresponding to $$m=k-1$$ exhibits good agreement with theory in terms of obtaining lower dissipated energy and smaller error rate, suggesting that the algorithm provides an effective, preferable approach for the design of Halbach shim coils.

Cu removal by a novel multi-amines decorated resin (PAMD) from wastewater in the absence or presence of citric acid (CA) was examined. Adsorption capacity of Cu onto PAMD markedly increased by 186% to 5.07 mmol/g in the presence of CA, up to 7 times of that onto four commercial resins under the same conditions. Preloaded and kinetic studies demonstrated adsorption of [Cu-CA] complex instead of CA site-bridging and variations of adsorbate species were qualitatively illustrated. The interaction configuration was further studied with ESI-MS, FTIR, XPS and XANES characterizations. The large enhancement of Cu adsorption in Cu-CA bi-solutes systems was attributed to mechanism change from single-site to dual-sites interaction in which cationic or neutral Cu species (Cu2+ and CuHL0) coordinated with neutral amine sites and anionic complex species (CuL− and Cu2L22−) directly interacted with protonated amine sites via electrostatic attraction and the ratio of the two interactions was approximately 0.5 for the equimolar bi-solutes system. Moreover, commonly coexisting ions in wastewaters had no obvious effect on the superior performance of PAMD. Also, Cu and CA could be recovered completely with HCl. Therefore, PAMD has a great potential to efficiently remove heavy metal ions from wastewaters in the presence of organic acids.