Affiner votre recherche
Résultats 111-120 de 4,895
Nanoporous bimetallic metal-organic framework (FeCo-BDC) as a novel catalyst for efficient removal of organic contaminants
2019
Li, Huanxuan | Zhang, Jian | Yao, Yuze | Miao, Xiangrui | Chen, Jiale | Tang, Junhong
In this work, we report on the synthesis and characterization of nanoporous bimetallic metal-organic frameworks (FeCo-BDC). Effects of synthesis time and temperature on the structures, morphology, and catalytic performance of FeCo-BDC were investigated. Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) were used to reveal the morphological and textural characteristics. The crystal structure and chemical composition of FeCo-BDC were determined by means of X-ray powder diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Photoelectron Spectroscopy (XPS), and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) measurements. Interestingly, FeCo-BDC grew into the same crystal structure with different morphology in the temperature of 110–150 °C with 12–48 h. The heterogeneous catalytic activity of FeCo-BDC was tested to activate peroxydisulfate (PDS) and peroxymonosulfate (PMS) for removal of methylene blue (MB). The results found that FeCo-BDC synthesized at 150 °C with 24 h exhibited the best catalytic performance for PMS and obtained 100% of MB removal within 15 min. The abundant unsaturated metal active sites of Fe(II) and Co(II) in the skeleton of FeCo-BDC made a great contribution to the generation of sulfate (▪) and hydroxyl radicals (OH), which resulted in the excellent performance for MB degradation.
Afficher plus [+] Moins [-]Study of aquatic life criteria and ecological risk assessment for triclocarban (TCC)
2019
Fan, Bo | Li, Ji | Wang, Xiaonan | Gao, Xiangyun | Chen, Jin | Ai, Shunhao | Li, Wenwen | Huang, Yun | Liu, Zhengtao
Triclocarban (TCC) is used as a broad-spectrum antimicrobial agent, the intensive detection of TCC in aquatic environments and its potential risks to aquatic organisms are concerned worldwide. In this study, 8 Chinese resident aquatic organisms from 3 phyla and 8 families were used for the toxicity tests, and four methods were employed to derive the aquatic life criteria (ALC). A criterion maximum concentration (CMC) of 1.46 μg/L and a criterion continuous concentration (CCC) of 0.21 μg/L were derived according to the USEPA guidelines. The acute predicted no effect concentrations (PNECs) derived by species sensitivity distribution (SSD) methods based on log-normal, log-logistic and Burr Type Ⅲ models were 2.64, 1.88 and 3.09 μg/L, respectively. The comparisons of ALCs derived with resident and non-resident species showed that the CMC and CCC of TCC derived with Chinese resident species could provide a sufficient protection for non-resident species. The higher toxicity of TCC on aquatic organisms was found compared with other antimicrobial agents (except for Clotrimazole) in aquatic environment. The strong positive linear correlation was observed between the TCC and TCS concentrations in aquatic environment with a correlation coefficient (R²) of 0.8104, it is of great significance in environmental monitoring and risk assessment for TCC and TCS. Finally, the ecological risk assessment showed that the TCC in Yellow River basin and Pearl River basin had higher risk with the mean potential affected fractions (PAFs) of 9.27% and 7.09%, and 22.10% and 15.00% waters may pose potential risk for 5% aquatic organisms, respectively. In general, the risk of TCC in Asian waters was higher than that in Europe and North America.
Afficher plus [+] Moins [-]Long-term effects of an early-life exposure of fathead minnows to sediments containing bitumen. Part I: Survival, deformities, and growth
2019
Vignet, C. | Frank, R.A. | Yang, Zhunhe | Wang, Z. | Shires, K. | Bree, M. | Sullivan, C. | Norwood, W.P. | Hewitt, L.M. | McMaster, M.E. | Parrott, J.L.
The aim of this study was to investigate the long-term effects of a short exposure to natural sediments within the Athabasca oil sand formation to critical stages of embryo-larval development in fathead minnows (Pimephales promelas). Three different sediments were used: Ref sediment from the upper Steepbank River tested at 3 g/L (containing 12.2 ng/g ∑PAHs), and two bitumen-rich sediments tested at 1 and 3 g/L; one from the Ells River (Ells downstream, 6480 ng/g ∑PAHs) and one from the Steepbank River (Stp downstream, 4660 ng/g ∑PAHs). Eggs and larvae were exposed to sediments for 21 days, then transferred to clean water for a 5-month grow-out and recovery period. Larval fish had significantly decreased survival after exposure to 3 g/L sediment from Stp downstream, and decreased growth (length and weight at 16 days post hatch) in Ells and Stp downstream sediments at both 1 and 3 g/L. Decreased tail length was a sensitive endpoint in larval fish exposed to Ells and Stp downstream sediments for 21 days compared to Ref sediment. After the grow-out in clean water, all growth effects from the bitumen-containing sediments recovered, but adult fish from Stp downstream 3 g/L sediment had significant increases in jaw deformities. The study shows the potential for fish to recover from the decreased growth effects caused by sediments containing oil sands-related compounds, but that some effects of the early-life sediment exposure occur later on in adult fish.
Afficher plus [+] Moins [-]Occurrence and distribution of phthalate esters in freshwater aquaculture fish ponds in Pearl River Delta, China
2019
Cheng, Zhang | Liu, Jun-Bo | Gao, Meng | Shi, Guang-Ze | Fu, Xiao-Jiao | Cai, Peng | Lv, Yan-Feng | Guo, Zhong-Bao | Shan, Chun-Qiao | Yang, Zhan-Biao | Xu, Xiao-Xun | Xian, Jun-Ren | Yang, Yuan-Xiang | Li, Kai-Bin | Nie, Xiang-Ping
The concentrations, congener profiles and spatial distribution of 13 phthalate esters (PAEs) in the freshwater fish ponds in the Pearl River Delta (PRD) region were investigated in water and sediment samples collect from 22 sites during Jul. 2016–Sept. 2017. The di-2-ethylhexyl phthalate (DEHP) was the predominant compounds in both water and sediment samples, accounting for 70.1% and 66.1% of ∑PAEs, respectively. The DEHP concentrations in the water samples collected from the sites of Zhongshan (35.7 μg/L), Jingmen (17.3 μg/L) and Nanhai (14.2 μg/L) were higher than that collected from other sampling sites (p <0.05), and exceed the Chinese environmental quality standards for surface water (DEHP, 8.00 μg/L). The concentrations of ΣPAEs (mean and median were 11.8 mg/kg dw and 7.95 mg/kg dw) in sediment was higher than that in sediment of river and estuary in the PRD region (p <0.05). The median concentrations of DEHP and di-n-butyl phthalate (DBP) exceeded recommend environmental risk limit (ERL) that posed a potential risk to the aquaculture fish pond environment in the PRD.
Afficher plus [+] Moins [-]Nutrient burial and environmental changes in the Yangtze Delta in response to recent river basin human activities
2019
Liu, Yueying | Deng, Bing | Du, Jinzhou | Zhang, Guosen | Hou, Lijun
High resolution sediment records in the Yangtze Delta front were constructed to reveal recent environmental changes in response to river basin human activities. Increases in nutrient and organic C influxes that began in the 1950s, together with elevated primary productivity and increased chemical fertilizer application, suggested a shift toward anthropogenic-predominated environmental changes during this period. The depletion of total organic C (TOC), total N (TN), and biogenic Si (BSi), along with the decline in sedimentation rate and coarsening of sediment coincided with the development of hydrological engineering in the river basin from the 1980s. Reservoir Si retention substantially altered river mouth primary productivity community composition from diatoms to non-diatoms, thereby changing the BSi/TOC molar ratio in the sediment profile. Estimation of biogenic component burial fluxes was conducted to assess the variation and potential impacts. A recent dramatic decline in biogenic component burial in the delta area suggested a low nutrient removal efficiency in this region, due to the decrease in sediment discharge. Consequently, more nutrients have been further transported to the inner shelf and open waters instead of being buried in the delta sediment, thereby increasing the environmental pressure in the Yangtze Delta and adjoining coastal area.
Afficher plus [+] Moins [-]Oxidative ageing induces change in the functionality of biochar and hydrochar: Mechanistic insights from sorption of atrazine
2019
Liu, Yuyan | Sohi, Saran P. | Jing, Fanqi | Chen, Jiawei
One attraction of using hydrochar (HC) and biochar (BC) in soil is their intrinsic affinity for organic contaminants. Oxidative ageing is likely to induce changes in physicochemical properties and functionality. To explore the long-term potential trajectories for corn stalk HC and BC to adsorb organic pollutants, we employed HC and BC exposure in 5% H2O2 to simulate oxidative ageing and get insights into mechanisms of atrazine adsorption on fresh and artificially aged materials. The physicochemical properties of fresh and aged materials were systematically compared using elemental analysis, SSA, FTIR, XPS and SEM-EDS, alongside K2Cr2O7/H2SO4 treatment to assess chemical oxidation stability. Atrazine is a typical herbicide chemical and hydrophobic organic pollutant. Adsorption isotherms of atrazine were used to reveal differences in mechanisms of sorption to BC and HC, by assessment before and ageing. BC freshly produced at 650 °C displayed higher capacity for atrazine sorption than BC produced at 500 °C, with a dominant role for π-π EDA interactions. The sorption capacity of HC freshly produced at 250 °C was higher than for HC produced at 200 °C HC, owing to higher C content and atrazine partitioning into the organic phase. Ageing increased the surface abundance of oxygenated functional groups for BC and HC and diminished bulk aromaticity. After ageing, atrazine sorption by high temperature BC was lower, but for HC it was increased. Such divergent effects must be considered when developing strategies to co-manage contaminants and carbon through the addition of carbonized materials to land.
Afficher plus [+] Moins [-]A spatio-temporally weighted hybrid model to improve estimates of personal PM2.5 exposure: Incorporating big data from multiple data sources
2019
Ben, YuJie | Ma, FuJun | Wang, Hao | Hassan, Muhammad Azher | Yevheniia, Romanenko | Fan, WenHong | Li, Yubiao | Dong, ZhaoMin
An accurate estimation of population exposure to particulate matter with an aerodynamic diameter <2.5 μm (PM₂.₅) is crucial to hazard assessment and epidemiology. This study integrated annual data from 1146 in-home air monitors, air quality monitoring network, public applications, and traffic smart cards to determine the pattern of PM₂.₅ concentrations and activities in different microenvironments (including outdoors, indoors, subways, buses, and cars). By combining massive amounts of signaling data from cell phones, this study applied a spatio-temporally weighted model to improve the estimation of PM₂.₅ exposure. Using Shanghai as a case study, the annual average indoor PM₂.₅ concentration was estimated to be 29.3 ± 27.1 μg/m³ (n = 365), with an average infiltration factor of 0.63. The spatio-temporally weighted PM₂.₅ exposure was estimated to be 32.1 ± 13.9 μg/m³ (n = 365), with indoor PM₂.₅ contributing the most (85.1%), followed by outdoor (7.6%), bus (3.7%), subway (3.1%), and car (0.5%). However, considering that outdoor PM₂.₅ makes a significant contribution to indoor PM₂.₅, outdoor PM₂.₅ was responsible for most of the exposure in Shanghai. A heatmap of PM₂.₅ exposure indicated that the inner-city exposure index was significantly higher than that of the outskirts city, which demonstrated that the importance of spatial differences in population exposure estimation.
Afficher plus [+] Moins [-]Effect of gibberellic acid on growth, photosynthesis and antioxidant defense system of wheat under zinc oxide nanoparticle stress
2019
Iftikhar, Azka | Ali, Shafaqat | Yasmeen, Tahira | Arif, Muhammad Saleem | Zubair, Muhammad | Rizwan, Muhammad | Alhaithloul, Haifa Abdulaziz S. | Alayafi, Aisha A.M. | Soliman, Mona H.
The production and soil accumulation of nanoparticles (NPs) from the industrial sector has increased concerns about their toxic effects in plants which needs the research to explore the ways of reducing NPs toxicity in pants. The gibberellic acid (GA) has been found to reduce abiotic stresses in plants. However, the effect of GA in reducing zinc oxide (ZnO) NPs-mediated toxicity in plants remains unclear. In this study, foliar application of GA was used to explore the possible role in reducing ZnO NPs toxicity in wheat (Triticum aestivum L.) plants. The plants were grown in pots spiked with ZnO NPs (0, 300, 600, 900, 1200 mg/kg) and GA (0, 100, 200 mg/L) was foliar sprayed at different times during the growth period under ambient environmental conditions. Our results demonstrated that GA inhibited the toxicity of ZnO NPs in wheat especially at higher levels of NPs. The GA application improved the plant biomass, photosynthesis, nutrients, and yield under ZnO NPs stress. The GA reduced the Zn accumulation, and reactive oxygen species generation in plants caused by toxicity of NPs. The protective effect of GA in decreasing ZnO NPs-induced oxidative stress was related to GA-mediated enhancement in antioxidant enzymes in plants. The role of GA in enhancing tolerance of wheat against ZnO NPs was further confirmed by the enhancement in nutrient contents in shoots and roots of wheat. Overall, our study provides the evidence that GA can reduce ZnO NPs-induced toxicity in wheat and probably in other crops which needs further in-depth investigation.
Afficher plus [+] Moins [-]Development of a liquid chromatography-quadrupole-time-of-flight-mass spectrometry based method for the targeted and suspect screening of contaminants in the pearl oyster Pinctada imbricata radiata
2019
Liu, Lan | Aljathelah, Noora Mahmood | Ḥasan, Ḥasan | Leitão, Alexandra | Bayen, Stéphane
A rapid method based on solvent extraction followed by direct injection in liquid chromatography-quadrupole-time-of-flight-mass spectrometry (LC-Q-TOF-MS) was developed for the targeted and suspect screening of contaminants in the soft tissues of the pearl oyster Pinctada imbricata radiata. The quantification method was first validated for the targeted analysis of 21 contaminants including some pharmaceutically active compounds, with the relative recoveries ranging from 88 to 123%, and method detection limits generally below 1 ng g⁻¹ on the wet weight (ww) basis. This targeted analysis method was then applied to oyster samples collected around the Qatari coast between 2017/2018, and none of the 21 compounds were detected in these samples. The post-acquisition data treatment based on the accurate mass measurement in both full MS scan and All Ions MS/MS was further used for mining other contaminants in oyster extracts, as well as 21 targeted compounds spiked in oyster extracts (suspect screening). The 21 spiked compounds were identified successfully and the estimated limit of identification for the individual 21 compounds ranged from 0.5 to 117 ng g⁻¹ ww of oyster tissues. A phthalate, di(2-ethylhexyl) phthalate (DEHP) was identified to be present in oyster extracts from 2018 batches, at a concentration level significantly higher than that in procedure blanks. These results confirmed that high resolution MS data obtained using the targeted method can be exploited through suspect screening workflows to identify contaminants in the tissues of bioindicator mollusks. However, a number of false identifications could be obtained and future work will be on improving the success rate of the correct identifications using this workflow.
Afficher plus [+] Moins [-]Effects of four food dyes on development of three model species, Cucumis sativus, Artemia salina and Danio rerio: Assessment of potential risk for the environment
2019
Motta, Chiara Maria | Simoniello, Palma | Arena, Carmen | Capriello, Teresa | Panzuto, Raffaele | Vitale, Ermenegilda | Agnisola, Claudio | Tizzano, Monica | Avallone, Bice | Ferrandino, Ida
Food dyes, or color additives, are chemicals added to industrial food products and in domestic cooking to improve the perceived flavor and attractiveness. Of natural and synthetic origin, their safety has been long discussed, and concern for human safety is now clearly manifested by warnings added on products labels. Limited attention, however, has been dedicated to the effects of these compounds on aquatic flora and fauna. For this reason, the toxicity of four different commercially available food dyes (cochineal red E120, Ponceau red E124, tartrazine yellow E102 and blue Patent E131) was assessed on three different model organisms, namely Cucumis sativus, Artemia salina and Danio rerio that occupy diverse positions in the trophic pyramid. The evidence collected indicates that food dyes may target several organs and functions, depending on the species. C. sativus rate of germination was increased by E102, while root/shoot ratio was ∼20% reduced by E102, E120 and E124, seed total chlorophylls and carotenoids were 15–20% increased by E120 and 131, and total antioxidant activity was ∼25% reduced by all dyes. Mortality and low mobility of A. salina nauplii were increased by up to 50% in presence of E124, E102 and E131, while the nauplii phototactic response was significantly altered by E102, E120 and E124. Two to four-fold increases in the hatching percentages at 48 h were induced by E124, E102 and E131 on D. rerio, associated with the occurrence of 20% of embryos showing developmental defects. These results demonstrated that the food dyes examined are far from being safe for the aquatic organisms as well as land organisms exposed during watering with contaminated water. The overall information obtained gives a realistic snapshot of the potential pollution risk exerted by food dyes and of the different organism' ability to overcome the stress induced by contamination.
Afficher plus [+] Moins [-]