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Application of Ti/IrO2 electrode in the electrochemical oxidation of the TNT red water Texte intégral
2020
Jiang, Nan | Wang, Yuchao | Zhao, Quanlin | Ye, Zhengfang
Via the thermal sintering, a nanocrystalline IrO₂ coating was formed on the Ti substrate to successfully prepare a Ti/IrO₂ electrode. Based on the electrochemical analysis, the prepared Ti/IrO₂ electrode was found to have powerful oxidation effect on the organics in the TNT red water, where the nitro compound was oxidized through an irreversible electrochemical process at 0.6 V vs. SCE. According to the analysis of the nitro compound content, the UV–vis spectra, and the FTIR spectra of 2,4,6-trinitrotoluene (TNT) red water with electrolytic periods, the degradation mechanism of the dinitrotoluene sulfonate (DNTS) was developed. And the intermediates were characterized by UPLC-HRMS. The DNTS mainly occurred one electron transfer reaction on the Ti/IrO₂ electrode. At the early stage of the electrolysis, the polymerization of DNTS was mainly dominated. The generated polymer did not form a polymer film on the electrode surface, but instead it promoted a further reduction. After electrolyzing for 30 h, all NO₂ function group in the TNT red water was degraded completely.
Afficher plus [+] Moins [-]Spatiotemporal variation of paralytic shellfish toxins in the sea area adjacent to the Changjiang River estuary Texte intégral
2020
Liu, Yang | Dai, Li | Chen, Zhen-Fan | Geng, Hui-Xia | Lin, Zhuo-Ru | Zhao, Yue | Zhou, Zheng-Xi | Kong, Fan-Zhou | Yu, Ren-Cheng | Zhou, Ming-Jiang
The Changjiang (Yangtze River) River estuary (CRE) and its adjacent coastal waters is a notable region for nutrient pollution, which results in severe problems of coastal eutrophication and harmful algal blooms (HABs). The occurrence of HABs, particularly those of dinoflagellate Alexandrium spp. capable of producing paralytic shellfish toxins (PSTs), has an increasing risk of contaminating seafood and poisoning human-beings. The investigation of PSTs, however, is often hampered by the relatively low abundance of Alexandrium spp. present in seawater. In this study, a monitoring strategy of PSTs using net-concentrated phytoplankton from a large volume of seawater was employed to examine spatiotemporal variations of PSTs in the CRE and its adjacent waters every month from February to September in 2015. Toxins in concentrated phytoplankton samples were analyzed using high-performance liquid chromatography coupled with a fluorescence detector (HPLC-FLD). The results showed that PSTs could be detected in phytoplankton samples during the sampling stage in the CRE and its adjacent waters. Toxin content increased gradually from February to May, reached the peak in June, and then decreased rapidly from July to September. The maximum value of PST content was 215 nmol m⁻³ in June. Low-potency toxins N-sulfocarbamoyl toxins 1/2 (C1/2) were the most dominant components of PST in phytoplankton samples from February to June in 2015, while high-potency gonyautoxin 4 (GTX4) became the dominant component from July to September. Toxins were mainly detected from three regions, the sea area north to the CRE, the sea area east to the CRE, and sea area near Zhoushan Island south to the CRE. Based on the results of this study, it can be inferred that the three regions around the CRE in May and June is of high risk for PST contamination and seafood poisoning.
Afficher plus [+] Moins [-]Profiling epigenetic changes in human cell line induced by atrazine exposure Texte intégral
2020
Sánchez, Oscar F. | Lin, Li | Bryan, Chris J. | Xie, Junkai | Freeman, Jennifer L. | Yuan, Chongli
How environmental chemicals can affect and exert their toxic effect at a molecular level has gained significant interest in recent years, not only for understanding their immediate health implications over exposed individuals, but also for their subsequent progeny. Atrazine (ATZ) is a commonly used herbicide in the U.S. and a long-suspected endocrine disrupting chemical. The molecular mechanism conferring long-term adverse health outcomes, however, remain elusive. Here, we explored changes in epigenetic marks that arise after exposure to ATZ at selected doses using image-based analysis coupled with data clustering. Significant decreases in methylated CpG (ᵐᵉCpG) and histone 3 lysine 9 tri-methylated (H3K9me3) were observed in the selected human cell line with a clear spatial preference. Treating cells with ATZ leads to the loss of a subpopulation of cells with high ᵐᵉCpG levels as identified in our clustering and histogram analysis. A similar trend was observed in H3K9me3 potentially attributing to the cross-talking between ᵐᵉCpG and H3K9me3. Changes in ᵐᵉCpG are likely to be associated with alterations in epigenetic enzyme expression levels regulating ᵐᵉCpG and persist after the removal of ATZ source which collectively provide a plausible mechanism for long-term ATZ-induced toxicity.
Afficher plus [+] Moins [-]Maternal preconception phthalate metabolite concentrations in follicular fluid and neonatal birth weight conceived by women undergoing in vitro fertilization Texte intégral
2020
Wu, Lin-Jing | Teng, Xue-Mei | Yao, Yang-Cheng | Liu, Chong | Du, Yao-Yao | Deng, Tao-Ran | Yuan, Xiao-Qiong | Zeng, Qiang | Li, Yu-Feng | Guo, Na
Exposure to phthalates during gestation has been associated with decreased birth weight among offspring. However, the associations between preconception phthalate metabolites in follicular fluid (FF) and offspring birth weight among women undergoing in vitro fertilization (IVF) remain largely unknown. Here, we explored the associations between preconception phthalate metabolite concentrations in FF and the birth weights of singletons and twins among women undergoing IVF. We recruited 147 female participants who gave birth to 90 singletons and 57 twin infants at the Reproductive Medicine Center, Tongji Hospital, Wuhan, between November and December 2016. Each participant was asked to complete a questionnaire at the time of recruitment and provide a FF sample on the day of oocyte retrieval. The FF concentrations of eight phthalate metabolites were determined using high-performance liquid chromatography and tandem mass spectrometry. Birth outcomes were abstracted from medical records. The associations between phthalate metabolites in FF and birth weights of the singleton and twin groups were evaluated using generalized linear models (GLMs). We found that birth weight in the twin group had negative dose-response associations with maternal preconception monobenzyl phthalate (MBzP) and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) in FF (both P for trends < 0.05) and that birth weight in the singleton group had positive dose-response associations with monoethyl phthalate (MEP) and mono(2-ethyl-5 hydroxyhexyl) phthalate (MEHHP) in FF (both P for trends < 0.05). These associations persisted when we modeled as continuous variables. In addition, we observed male-specific association between decreased twin birth weight and MEOHP and MBzP and a female-specific associations between increased singleton birth weight and MEP, MEHHP and the sum of di(2-ethylhexyl) phthalate (∑DEHP) (all P for interactions < 0.05). Preconception phthalate metabolites in maternal FF may affect the birth weights of both singleton and twin newborns.
Afficher plus [+] Moins [-]Human health risk and potential environmental damage of organic and conventional Nicotiana tobaccum production Texte intégral
2020
Zappe, Ana Letícia | Fernandes de Oliveira, Priscila | Boettcher, Ricardo | Rodriguez, Adriane Lawisch | Machado, Ênio Leandro | Mantey dos Santos, Pâmela Andréa | Rodriguez Lopez, Diosnel Antonio | Amador de Matos, Manuel Arlindo
Tobacco is the most widespread non-food crop in the world. In Brazil, tobacco cultivation is one of the main commodities of the southern region. However, its production is associated with environmental impacts and risks to human health, which have yet to be quantified. This paper uses midpoint and endpoint life cycle assessment (LCA) to analyze the potential environmental damage and human health risk associated with agricultural production of conventional Virginia (CV), organic Virginia (OV), and Burley (BU) tobacco varieties. Organic tobacco production substitutes synthetic fertilizers and pesticides with organic compounds in the cropping stage. The results show that for one ton of dried tobacco, BU, CV, and OV emit 1,610, 1,426, and 1,091 kg CO₂ eq, respectively. For organic production, greater impacts are linked to the land use (LU) impact category. The endpoint results showed that OV production resulted in a higher potential for human and environmental damage than BU and CV. The drying of green OV and CV tobacco requires the burning of firewood, which emits high levels of particulate matter and is associated with human health (HH) damage. Overall, the HH damage category accounts for 68%, 82%, and 78% of the total score points associated with the production of BU, CV, and OV.
Afficher plus [+] Moins [-]Triazole resistance in Aspergillus fumigatus in crop plant soil after tebuconazole applications Texte intégral
2020
Cao, Duantao | Wu, Ruilin | Dong, Suxia | Wang, Feiyan | Ju, Chao | Yu, Sumei | Xu, Shiji | Fang, Hua | Yu, Yunlong
Aspergillus fumigatus is the primary agent of invasive aspergillosis (IA) causing high morbidity and mortality in immunocompromised patients. Triazole resistance in A. fumigatus and its sources have gained wide attention. For several years, environmental fungicides use has been proposed as the major cause for triazole resistance in A. fumigatus. However, there are few studies on azole-resistant A. fumigatus (ARAF) selected by triazole fungicides in agricultural systems. We studied the possible emergence of ARAF in the field after exposure to triazole fungicide tebuconazole. Our results showed that exposure to tebuconazole in soil selects for resistance to triazoles in A. fumigatus. The probability of ARAF developing in soils depends upon the concentrations of tebuconazole after application. We suggest that tebuconazole applications should be minimized to reduce selective pressure for the generation of ARAFs.
Afficher plus [+] Moins [-]Nitrogen induced DOC and heavy metals leaching: Effects of nitrogen forms, deposition loads and liming Texte intégral
2020
Zia, Afia | van den Berg, Leon | Riaz, Muhammad | Arif, Muhammad | Zia, Dania | Khan, Shawana J. | Ahmad, Muhammad Nauman | Attaullah, | Ahsmore, Mike
Atmospheric nitrogen (N) deposition is believed to accelerate dissolved organic carbon (DOC) production and could lead to increased heavy metal mobility into water resources. We sampled intact soil cores from the Isle of Skye with low background N deposition history and having Serpentine rock known for its higher heavy metal concentrations including zinc (Zn), copper (Cu), nickel (Ni) and lead (Pb). The effects of 16 (16kgN) and 32 kg N ha⁻¹ year⁻¹ (32kgN), and liming with 32kgN (32kgN+Lime) on soil solution chemistry and heavy metal mobilization were investigated over the 15-month study. Nitrogen in deposition load was added at five ammonium (NH₄⁺) to nitrate (NO₃⁻) ratios of 9:1, 5:1, 1:1, 1:5 and 1:9 along NO₃⁻dominance. We found significant effects of load on Cu and NH₄⁺/NO₃⁻ ratio on pH, DOC and Zn in soil solution. However, under lime and ratio experimental factors, liming significantly influenced pH, DOC, Cu and Pb, and NH₄⁺/NO₃⁻ ratio pH, DOC, Ni and Zn whereas interactions between lime and ratio was significant for Ni and Cu. pH and DOC increased with N load, liming and NO₃⁻ dominance, and both correlated significantly positively. Liming under NH₄⁺ dominance enhanced DOC production due to supply of base cations in lime. Mobilization of Cu, Ni and Pb was driven by DOC concentrations and, therefore, increased with load, liming and NO₃⁻ dominance in deposition. However, in contrast, low pH and high NH₄⁺ dominance was associated with Zn mobilization in soil solution. On the contrary, despite of some patterns, heavy metals in soil HNO₃ extracts were devoid of any load, lime and NH₄⁺/NO₃⁻ ratio effects. Our study suggests that the effects of N load and forms in deposition on sites with high accumulated loads of metals need to be better quantified through soil solution partitioning models.
Afficher plus [+] Moins [-]Nano-magnetite supported by biochar pyrolyzed at different temperatures as hydrogen peroxide activator: Synthesis mechanism and the effects on ethylbenzene removal Texte intégral
2020
Yan, Jingchun | Yang, Lei | Qian, Linbo | Han, Lu | Chen, Mengfang
Nano-magnetite supported by biochar (nFe₃O₄/BC) pyrolyzed at temperatures of 300 °C–600 °C was developed to activate hydrogen peroxide (H₂O₂) for the efficient degradation of ethylbenzene in aqueous solution. It was revealed that the degradation efficiency of ethylbenzene and TOC removal were 96.9% and 36.2% respectively after the reaction for 40 min in the presence of initial concentration of 0.1 mmol L⁻¹ ethylbenzene, 2.76 g L⁻¹ nFe₃O₄/BC₅₀₀ with the mass ratio of nFe₃O₄ to BC₅₀₀ of 4:1 and 2.0 mmol L⁻¹ H₂O₂ at pH 7.0. Based on electron paramagnetic resonance (EPR), quenching experiment and X-ray photoelectron spectroscopy (XPS) data, both OH and O₂⁻ radicals were generated in the nFe₃O₄/BC₅₀₀ activated H₂O₂ system, and the OH radicals were the predominant species for the degradation of ethylbenzene. Through electron transfer process, mechanisms of Fe(II), phenolic hydroxyl group and persistent free radicals (PFRs) on BC surfaces accounted for the generation of OH radicals, and Fe(III) in nFe₃O₄ and formed from Fe(II) oxidation responsible for the generation of O₂⁻ radicals in the nFe₃O₄/BC activated H₂O₂ system were proposed.
Afficher plus [+] Moins [-]Transcriptional profiles and copper stress responses in zebrafish cox17 mutants Texte intégral
2020
Sun, HaoJie | Chen, Mingyue | Wang, Ziyang | Zhao, Guang | Liu, Jing-Xia
While Cox17 functions importantly in copper metalation of cytochrome c oxidase and integral mitochondrial architecture in vertebrates, rare studies have been performed regarding the developmental and physiological characters of vertebrate cox17 mutants. In this study, normal-like developmental phenotype was observed in both cox17Δ6−/− and cox17Δ4−/− homozygous zebrafish mutants, while gene ontology term and pathway analysis of the differentially expressed genes in both mutants showed enrichment in oxidoreductase activity, ion transport, histone methylation, MICOS complex, Wnt signaling, etc. This implied the occurrence of damage to the integral function of Cox17 and change of transcriptomes in the two mutants. Further qRT-PCR and WISH assays revealed the down-regulated expression of Wnt signaling and reduced expression of swim bladder marker genes in the two mutants. Moreover, copper stimulation induced no obvious increase in reactive oxygen species (ROS) or in the expression of hemoglobin marker genes, but further reduced the expression of swim bladder marker genes in the mutants. The integral data in this study suggest that: (1) cox17 mutants cannot activate the response of oxidoreductase to copper stimulation; (2) copper depends on the integral function of Cox17 to induce developmental defects in hemoglobin rather than swim bladder and (3) Wnt signaling but not ROS might mediate copper-induced swim bladder developmental defects in fish.
Afficher plus [+] Moins [-]Cadmium and kidney function: Concentrations, variabilities, and associations across various stages of glomerular function Texte intégral
2020
Jain, Ram B.
Data (N = 10336) from National Health and Nutrition Examination Survey for 2003–2016 for US adults aged ≥ 20 years were analyzed to evaluate the concentrations of blood and urine cadmium across the various stages of glomerular function. Estimated glomerular filtration rate (eGFR) > 90 mL/min/1.73 m2 was defined to be glomerular function stage 1 (GF-1), eGFR between 60 and 90 mL/min/1.73 m2 defined as GF-2, eGFR between 45 and 60 mL/min/1.73 m2 as GF-3A, and eGFR between 15 and 45 mL/min/1.73 m2 as GF-3B/4. Regression models stratified by GF-stages were fitted to estimate associations between the observed levels of blood and urine cadmium across stages of GF. Based on the results of stratified modes, there were consistent increases in adjusted geometric means (AGMSM) for both blood and urine cadmium from GF-1 to GF-3A although increases were not uniform from one GF stage to another. For the total population, AGMSM for blood and urine cadmium were GF-1 (0.47, 0.24), GF-2 (0.60, 0.37), GF-3A (0.72, 0.45), and GF-3B/4 (0.73, 0.45) μg/L. respectively. Although females had higher AGMSMs than males for both blood and urine cadmium, the difference in blood cadmium narrowed as kidney function deteriorated. Smokers had the steepest increases in AGMSMs for blood and urine cadmium across the stages of glomerular function and smoker-nonsmoker differences for blood cadmium narrowed as kidney function deteriorated but smoker-nonsmoker differences for urine cadmium widened as kidney function deteriorated. The important physiologic messages are that both blood and urine cadmium cease to increase from GF-3A to GF-3B/4, suggesting a new steady state based on renal failure. And, the narrowed difference in blood cadmium in smokers vs. nonsmokers suggests why this happens. Incremental exposures to cadmium are offset by excretion as renal failure progresses.
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