An emission model for inhalable chemicals from children's play mats based on partition coefficients.

Inhalable chemicals found in children's play mats can be slowly released into indoor environments and consequently threaten human health. In this study, the partition coefficients of seven inhalable chemicals between play mats and air were calculated by headspace gas chromatography-mass spectrometry based on the law of conservation of mass and the principle of equilibrium of headspace bottles. Furthermore, an emission source model for the residual ratio of the inhalable chemicals in play mats was established. Most substances found in play mats have large partition coefficients owing to the complex void structure of the mats, which adsorbs a large number of organic pollutants. The partition coefficient is not only related to the boiling point and environmental temperature, but also the specific material and the adsorption of the organic pollutant onto the material. The emission source model for children's play mats developed in this study can characterize the decay of the inhalable chemicals over time. The data showed that after eight days of placing the play mat in a ventilated environment, the residual ratio of seven inhalable chemicals did not exceed 15 %.

A framework for risk assessment of groundwater contamination integrating hydrochemical, hydrogeological, and electrical resistivity tomography method.

Groundwater contamination have been widely concerned. To reliably conduct risk assessment, it is essential to accurately delineate the contaminant distribution and hydrogeological condition. Electrical resistivity tomography (ERT) has become a powerful tool because of its high sensitivity to hydrochemical parameters, as well as its advantages of non-invasiveness, spatial continuity, and cost-effectiveness. However, it is still difficult to integrate hydrochemical, hydrogeological, and ERT datasets for risk assessment. In this study, we develop a general framework for risk assessment by sequentially jointing hydrochemical, hydrogeological, and ERT surveys, while establishing petrophysical relationships among these data. This framework can be used in groundwater-contaminated site and help to delineate the distribution of contaminants. In this study, it was applied to a nitrogen-contaminated site where field ERT survey and borehole information provided valuable measurement data for validating the consistency of contamination and hydrogeological condition. Risk assessment was conducted based on the refined results by the establishment of relationship between conductivity and contaminants concentration with R 2 > 0.84 . The contamination source was identified and the transport direction was predicted with the good agreement of R 2 = 0.965 between simulated and observed groundwater head, which can help to propose measures for anti-seepage and monitoring. This study thus enhances the reliability of risk assessment and prediction through a thought-provoking innovation in the realm of groundwater environmental assessment.

Monitoring of in-situ chemical oxidation for remediation of diesel-contaminated soil with electrical resistivity tomography.

In-situ chemical oxidation (ISCO) with persulfate, an electrically conductive oxidant, provides a powerful signal for noninvasive geophysical techniques to characterize the remediation process of hydrocarbon contaminants. In this study, remediation with ISCO is conducted in laboratory sandboxes to evaluate the ability of electrical resistivity tomography (ERT) for monitoring the base-activated persulfate remediation process of diesel-contaminated soil. It was found that the resistivity of contaminated sand significantly decreased from 846 Ω·m to below 10 Ω·m after persulfate injection, and all measured chemical parameters showed a noticeable increase. Natural degradation and contamination plume migration were not evident in a reference sandbox without treatment. The area with a resistivity ratio < 0.95 based on imaging before and after injection indicated downward migration of the oxidation plume due to density-driven flow. A comparison between remediation and reference sandboxes showed that the observed resistivity decrease can be due to both contaminant degradation as well as the oxidation plume itself in the contaminated source zone. In contrast, the resistivity decrease in the area with low contamination concentration is attributed to the oxidation plume alone. The derived relationships between resistivity and contaminant indicators further emphasize that the contribution of contaminant consumption to resistivity change in the source area is 25.6%, while it is <16% in the low or non-contaminated area. Although this study showed that resistivity is not solely affected by the chemical transformation of diesel components, it can be combined with sampling data to allow an assessment of the effectiveness of ISCO treatment and to identify target areas for subsequent treatment.

Metagenomics analysis of antibiotic resistance genes, the bacterial community and virulence factor genes of fouled filters and effluents from household water purifiers in drinking water.

The aim of this study was to explore the influence and removal of household water purifiers (HWPs) on emerging contaminants in drinking water, and their distribution characteristics. The antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), virulence factor genes (VFGs) and bacterial communities were profiled in the fouled filters, influents, and effluents from HWPs with five steps of filtration after 150 days operation, using metagenomics. The results showed that the diversity of dominant species in Poly Propylene 1 µm (PP1) and nanofiltration membrane (NM) was significantly higher than that in other filters. Post-activated carbon (AC) was used to detect low species richness or diversity, and the highest proportion of dominant species, which contributes to the greater microbial risk of HWPs effluents in drinking water. The number of dominant bacterial genera in the filters disinfected with chloramine was higher than that in the same group disinfected with chlorine. The bacterial species richness or diversity in water was reduced by the purification of HWPs because the filter elements effectively trapped a variety of microorganisms. The relative abundance of Antibiotic efflux in the effluents of chlorinated and chloraminated HWPs was 5.58 × 10-3 and 4.60 × 10-3, respectively, which was the main resistance mechanism. High abundance of VFGs was found in HWPs effluents and the relative abundance of aggressive VFGs was significantly higher than those of defensive VFGs. Based on the co-occurrence results, 243 subtypes of ARGs co-occurred with VFGs, and a variety of bacteria were thought to be possible ARGs hosts, which indicated that the host bacteria of VFGs in HWP effluents had a stronger attack ability. The effluent of HWPs with only filtration processes is exposed to the risk of ARGs and VFGs. This study helps to understand the actual purification effect of HWPs and provides a theoretical reference for the management and control of ARGs pollution in domestic drinking water.

An ionic covalent organic framework for rapid extraction of polar organic acids from environmental waters.

An ionic covalent organic framework (Fe3O4@EB-TFB-iCOF) as a polar adsorbent was synthesized and characterized. It was applied in the magnetic solid phase extraction (MSPE) of four polar organic acids, namely, 2-(2,4,5-trichlorophenoxy)propionic acid, 2-methyl-4-chlorophenoxy acetic acid, naphthyloxyacetic acid, and naphthylacetic acid. The organic acids were detected by high performance liquid chromatography-ultraviolet analysis (HPLC-UV). A method for the determination of organic acids based on MSPE-HPLC-UV was established. The method shows good linear regression (R2≥ 0.9950), high precision (1.53-3.80%, n = 6), and low detection limit (0.10-0.49 ng mL-1). The recovery rate of environmental water samples ranges from 73.3% to 101.0%. This method provides a possibility for high sensitivity analysis of polar organic acids.

Caramelized carbonaceous shell-coated γ-Fe2O3 as a magnetic solid-phase extraction sorbent for LC-MS/MS analysis of triphenylmethane dyes.

Carbonaceous shell-coated γ-Fe2O3 nanoparticles (γ-Fe2O3@CNM) were synthesized from glucose caramelization and used as a novel magnetic solid-phase extraction medium for malachite green and crystal violet in environmental water. Malachite green and crystal violet were absorbed on to γ-Fe2O3@CNM by electrostatic and π-interactions. The morphologies, pore structures, surface functional groups, and magnetic properties of γ-Fe2O3@CNM were characterized by TEM, FTIR, hysteresis regression, Brunauer-Emmet-Teller analysis, zeta potential, XPS, and XRD. The magnetic solid-phase extraction procedure was optimized by extraction pH, absorption time, desorption solvent, and desorption time. The absorption capacities (qmax values) for malachite green and crystal violet were 34.2 and 27.9 mg g-1, respectively. After magnetic solid-phase extraction, malachite green and crystal violet were determined by LC-MS/MS. The analytical method was validated with a linear range of 0.02-20 ng mL-1, enrichment factor of 25.8 and 25.4, method detection limit of 0.004 ng mL-1, and intra-day precisions of 2.1% and 2.6% for malachite green and crystal violet, respectively. The relative recovery was found to be 73.4-101.5% for malachite green and 83.1-102.7% for crystal violet upon the application of the magnetic solid-phase extraction method to real water samples from lake, spring, sea, fishpond, and industrial waste. Graphical abstract Caramelized-carbon-coated magnetic nanoparticles are used as novel extraction medium based on electrostatic and π-interactions. It is porous, amphiphilic, electronegative, magnetically strong, and features abundant absorption site. These characteristics stimulate mass transfer and result in a useful MSPE method in environmental analysis.

A 3D spongy flexible nanosheet array for on-site recyclable swabbing extraction and subsequent SERS analysis of thiram.

A sponge inspired three dimensional flexible aluminum foil based ZnO nanosheet array substrate is described for use in real-world surface enhanced Raman spectroscopic detection. Gold and silver nanoparticles were employed to form numerous hot spots on uniformly grown ZnO nanosheets on the substrate. This flexible spongy substrate can extract analytes (such as the fungicide thiram) from various complex sample surfaces by physical swabbing. Specifically, this substrate was applied to detect thiram on the surface of fruits and vegetables. Non-destructive recycling detection with a relative standard deviation of 6.1% was accomplished by monitoring the characteristic Raman peak at 1382 cm-1. This modified substrate has a low detection limit (0.2 ng cm-2 of thiram for apple and tomato), outstanding uniformity (relative standard deviation = 8.9%) and thermal stability (relative standard deviation = 0.9%). Graphical abstract Schematic representation of using a aluminum foil modified with ZnO nanosheets as a flexible and recyclable substrate for SERS analysis of pollutants. The substrate can be cleaned after use by UV irradiation.

A core-shell structured magnetic covalent organic framework (type Fe3O4@COF) as a sorbent for solid-phase extraction of endocrine-disrupting phenols prior to their quantitation by HPLC.

A magnetic covalent organic framework (Fe3O4@COF) with core-shell structure was fabricated at room temperature and used as an adsorbent for magnetic solid-phase extraction of polar endocrine-disrupting phenols (4-n-nonylphenol, 4-n-octylphenol, bisphenol A and bisphenol AF). The sorbent was characterized by transmission electron microscopy, FTIR, powder X-ray diffraction and other techniques. The main parameters governing the extraction efficiency were optimized. The phenols were quantified by HPLC with fluorometric detection. The method has attractive features such as low limits of detection (0.08-0.21 ng.mL-1), wide linear ranges (0.5-1000 ng.mL-1), and good repeatability (intra-day: 0.39%-4.99%; inter-day: 1.57%-5.21%). Satisfactory results were obtained when the developed method was applied to determine the four target pollutants in real world drink samples with spiked recoveries over the range of 81.3~118.0%. This indicates that the method is a powerful tool for the enrichment and determination of endocrine-disrupting phenols in drink samples. Graphical abstract A magnetite based covalent organic framework (Fe3O4@COFs) was synthesized with TPAB, TPA and Fe3O4. It was used for magnetic solid-phase extraction of endocrine-disrupting phenols from plastic-packaged tea drink samples coupled with liquid chromatography (LC) for determination.

Well-dispersed Pd nanoparticles on porous ZnO nanoplates via surface ion exchange for chlorobenzene-selective sensor.

The extensive use of chlorobenzene in chemical, pharmaceutical, and agrochemical industries poses a severe health hazard to human beings, because it is highly toxic. The detection of chlorobenzene by metal oxide gas sensors is difficult, owing to its chemically inert molecular structure. In this study, well-dispersed Pd nanoparticles were deposited on porous ZnO nanoplates via surface ion exchange, followed by H2 reduction. The preparation process effectively prevented the aggregation and uncontrollable growth of Pd particles. A gas-sensing test was conducted, and the modification of size-controlled Pd nanoparticles was found to effectively enhance the sensing properties of porous ZnO nanoplates to chlorobenzene over 300 °C (higher sensitivity at a low operating temperature). At 440 °C, 5% Pd@ZnO sensor showed a drastic increase in response by nearly 4.5-fold, as well as excellent sensing selectivity to chlorobenzene. Its repeatability and stability were acceptable. As known, Pd nanocatalysts contribute to the oxidation of chlorinated aromatic compounds. Pd@ZnO sensors generated more catalytic sites and oxygen species (confirmed by XPS), thus enhancing chlorobenzene oxidation and improving the sensitivity of ZnO-based gas sensors.

Bioactive isopimarane diterpenes from the fungus, Epicoccum sp. HS-1, associated with Apostichopus japonicus.

One new isopimarane diterpene (1), together with two known compounds, 11-deoxydiaporthein A (2) and iso-pimara-8(14),15-diene (3) were isolated from the culture of Epicoccum sp., which was associated with Apostichopus japonicus. Their structures were determined by the analysis of 1D and 2D NMR, as well as mass spectroscopic data. The absolute configuration of Compound 1 was deduced by a single-crystal X-ray diffraction experiment using CuKα radiation. In the bioactivity assay, both Compounds 1 and 2 exhibited α-glucosidase inhibitory activity with IC50 values of 4.6 ± 0.1 and 11.9 ± 0.4 µM, respectively. This was the first report on isopimarane diterpenes with α-glucosidase inhibitory activity.