A detailed investigation was conducted to understand the contamination characteristics of a selected set of potentially toxic metals in Shanghai. The amount of Pb, Zn, Cu, Cr, Cd and Ni were ...determined from 273 soil/dust samples collected within urban area. The results indicated that concentration of all metals except Ni in soils was significant, and metal pollution was even severer in roadside dust. A series of metal spatial distribution maps were created through geostatistical analysis, and the pollution hotspots tended to associate with city core area, major road junctions, and the regions close to industrial zones. In attempt of identifying the source of metals through geostatistical and multivariate statistical analyses, it was concluded as follows: Pb, Zn and Cu mainly originated from traffic contaminants; soil Ni was associated with natural concentration; Cd largely came from point-sourced industrial pollution; and Cr, Ni in dust were mainly related to atmospheric deposition.
Human activities have led to high accumulation of potentially toxic metals in urban soils and roadside dust of Shanghai.
Urban and suburban road dust samples were collected in the most populated city of China, Shanghai. Size fractions of dust particles were analyzed; metal levels of the dust were also measured. Human ...exposure to individual toxic metals through road dust was assessed for both children and adults. The results showed that dust particles from urban and suburban road were presented similar size distribution pattern, with most particles in the range of 100–400
μm. Urban road dust consisted of higher proportions of inhalable, thoracic and respirable particles with increased risk of adverse effects to human. In general, mean grain sizes of urban road dust were smaller than suburban dust. Total organic carbon contents and levels of Pb, Cd, Cu, Zn, Ni, Cr in urban dust were higher than those of suburban dust. But the concentrations of As and Hg from suburban dust were higher, indicting a different main source. The exposure pathway which resulted in the highest level of risk for human exposed to road dust was ingestion of this material, which was followed by dermal contact. Except for some locations, risk values of both cancer and non-cancer obtained in this study were in the receivable range on the whole. Children had greater health risks than adults. The overall risks of non-cancer in urban area were higher than those in suburban area, but the values of cancer in the two areas were comparable. As for the aggregate noncarcinogenic risk, Pb was of most concern regarding the potential occurrence of health impacts. Of the three carcinogenic metals As, Cr and Cd, the only mean risk higher than 10
−6 was Cr, accounting for a great percentage (95%) of the overall risk of cancer. Hence, potentially adverse health effects arising from Pb and Cr in road dust should arouse wide concern.
•Construct correlations and regression models between land use pattern and SUHII level.•Include the function guided layout of green space into the future land use simulations.•Predict the future ...SUHII in 2030 based on the regression models in 2014.•Analyze the differences of SUHI mitigation under future land use multi-scenarios.
The distribution and morphology of urban green space (UGS) have a significant impact on its ability to mitigate surface urban heat island intensity (SUHII). In this study, the Future Land Use Simulation model was used to predict land use in Xuchang City by 2030 under three different scenarios. Landsat Operational Land Imager images from 2014 were used to calculate SUHII. And, the relationships and regression models between summer SUHII and land use data were analyzed and developed. The SUHII in 2030 based on simulated land use was predicted using regression models in 2014. Results showed that reductions in SUHII were greater under present land use scenario with a greater proportion of UGS. Furthermore, the degree of aggregation, average patch area, maximum patch shape index, and complexity of the green space also impacted the effectiveness of SUHII mitigation. In future land use scenarios with different constraints, the ecological service function guided scenario was the most effective at mitigating SUHII. These findings provide a reference for the reasonable allocation of urban land and the optimization of UGS in terms of SUHII reduction in small- and medium-sized cities where there is a need for expansion.
Conventional reconnaissance camera systems have been flown on manned aircraft, where the weight, size, and power requirements are not stringent. However, today, these parameters are important for ...unmanned aerial vehicles (UAVs). This article provides a solution to the design of airborne large aperture infrared optical systems, based on a monocentric lens that can meet the strict criteria of aerial reconnaissance UAVs for a wide field of view (FOV) and lightness of airborne electro-optical pod cameras. A monocentric lens has a curved image plane, consisting of an array of microsensors, which can provide an image with 368 megapixels over a 100° FOV. We obtained the initial structure of a five-glass (5GS) asymmetric monocentric lens with an air gap, using ray-tracing and global optimization algorithms. According to the design results, the ground sampling distance (GSD) of the system is 0.33 m at 3000 m altitude. The full-field modulation transfer function (MTF) value of the system is more than 0.4 at a Nyquist frequency of 70 lp/mm. We present a primary thermal control method, and the image quality was steady throughout the operating temperature range. This compactness and simple structure fulfill the needs of uncrewed airborne lenses. This work may facilitate the practical application of monocentric lens in UAVs.
Although epoxiconazole is the worldwidely used fungicide, limited information is known about its toxic effects and bioaccumulation behavior in freshwater ecosystems. In this study, zebrafish were ...exposed to epoxiconazole at concentrations of 100 and 1000 μg L−1 for 21 d. 1H NMR-based metabolomics analysis showed that low- and high-dose epoxiconazole exposure resulted in two similar but not identical patterns for the change of endogenous metabolites related to energy, lipid and amino acid metabolism. The expression of genes associated with mitochondrial respiratory chain, ATP synthesis and fatty acid β-oxidation were further measured to explore the reason for the disturbed energy metabolism, finding epoxiconazole had an inhibition effect on the genes expression of the above ways. Significant enantioselectivity was observed with (+)-epoxiconazole enrichment in the bioaccumulation process. These results will be of great importance in understanding the toxic effects induced by epoxiconazole and provide important basis for its comprehensive environmental assessment.
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•The bioaccumulation of epoxiconazole in adult zebrafish was enantioselective.•Epoxiconazole disturbed the energy, amino acid and lipid metabolism of zebrafish.•Epoxiconazole affected the expression of energy metabolism genes in zebrafish.
Previous studies have demonstrated the endocrine disruption of o,p′-DDT. In this study, we used a 1H NMR based metabolomics approach to investigate the estrogenic effects of o,p′-DDT (300 mg/kg) on ...the uterus and brain after 3 days of oral gavage administration, and ethynylestradiol (EE, 100 μg/kg) was used as a positive control. A supervised statistical analysis (PLS-DA) indicated that o,p′-DDT exerted both estrogenic receptor-(ER)-dependent and independent effects on the uterus but mainly ER-independent effects on the brain at metabolome levels, which was verified by coexposing with the antiestrogenic ICI 182,780. Four changed metabolitesglycine, choline, fumarate, and phenylalaninewere identified as ER-independent alterations in the uterus, while more metabolites, including γ-aminobutyrate, N-acetyl aspartate, and some amino acids, were disturbed based on the ER-independent mechanism in the brain. Together with biological end points, metabolomics is a promising approach to study potential estrogenic chemicals.
Although isocarbophos is a widely used insecticide, its toxicity to aquatic organisms has not been well characterized. In this study, zebrafish were exposed to isocarbophos at concentrations of ...50 µg L−1 and 200 µg L−1 to assess its bioaccumulation, metabolic disruption, and oxidative stress. Metabolomics analysis based on 1H NMR spectroscopy showed that 50 µg L−1 and 200 µg L−1 isocarbophos exposure induced increases in leucine, isoleucine, valine, and alanine compared to levels in the control. Lactate, creatine, and taurine were reduced in the 50 µg L−1 isocarbophos exposure group, and only lactate decreased in response to 200 µg L−1 isocarbophos. After zebrafish were exposed to 50 and 200 µg L−1 isocarbophos for 28 days, the activities of antioxidant enzymes (SOD, CAT, and GPx) and GSH contents decreased significantly in the liver. This result indicates that there was significant oxidative stress in the liver. Furthermore, changes in metabolite profiles significantly covaried with changes in several oxidative stress endpoints based on partial least squares regression. These results will contribute to the environmental risk assessment of isocarbophos and clarify the mechanism underlying its toxicity in zebrafish.
•Isocarbophos will be enriched in adult zebrafish.•Isocarbophos disturbed the energy and amino acid metabolism of zebrafish.•Isocarbophos caused significant oxidative stress in adult zebrafish.
Endosulfan, an organochloride pesticide, has been used for many commercial purposes. Endosulfan is composed of two isomers, α-endosulfan and β-endosulfan. In biological and soil systems, endosulfan ...is metabolized into endosulfan sulfate. In this study, the different toxicological effects of α-endosulfan, β-endosulfan, and endosulfan sulfate on the livers and kidneys of mice were comprehensively investigated. The results demonstrated that both endosulfan isomers and endosulfan sulfate disturbed the hepatic and renal antioxidant systems. Furthermore, 1H NMR metabolomics analysis revealed that endogenous metabolites involved in oxidative stress and energy metabolism were altered after exposure to these compounds. In the liver, the changes in hepatic endogenous metabolites and the induction of hepatic CYP450 mRNA isoforms were similar among mice treated with the three compounds, and the sulfate metabolite was the exclusive exogenous compound detected. Therefore, the metabolism of α- and β-endosulfan to endosulfan sulfate is likely the main cause of toxicological effects in the livers of mice. However, in kidneys, the changes in the metabolome and in CYP450 mRNA expression induced by α-endosulfan and β-endosulfan were stereoselective. Additionally, endosulfan sulfate, which induced a significant increase of renal Cyp3a11, showed a more robust disturbance of renal metabolites than either of the two isomers. These findings revealed that more attention should be given to the toxicological evaluation of endosulfan sulfate in the future.
•Isomers and metabolite of endosulfan affected oxidative stress and energy metabolism in mice liver and kidney.•The three endosulfan compounds induced the different CYP450 isoforms in the livers and kidneys of mice.•Disturbances in metabolome and CYP450s expression by endosulfan compounds between livers and kidneys were dissimilar.•Endosulfan sulfate is likely the main cause of toxicological effects in the livers of mice.
Gd-doped monazite-(Ce) ceramics (Ce0.9Gd0.1PO4) have been fabricated by hot-press sintering (HPS) and pressureless sintering (PLS). The influence of sintering temperature and holding time on the bulk ...density and microstructure was investigated. The results show all of HPS samples are denser than the PLS samples, even if the optimal PLS temperature is as high as 1400°C and the HPS temperature is only 1150°C. Low-temperature densification of the HPS ceramics should be attributed to particle rearrangement under pressure. In addition, chemical durability testing was carried out using the standard MCC-1 static leach test method. The results indicate that the normalized elemental leach rates of HPS samples are higher than those of PLS sintered specimens before 21 days, and remained almost unchanged (RL (Ce)≤6.0×10−6gm−2d−1, RL (Gd)≤1.8×10−5gm−2d−1) in both HPS and PLS ceramics after 28 days. The low-temperature HPS process to prepare monazite-based ceramic is a promising method for immobilizing trivalent minor actinide.
