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24761. 题目: Variations of soil organic matters and plant cuticular waxes along an altitude gradient in Qinghai-Tibet Plateau
文章编号: N19101602
期刊: Plant and Soil
作者: Luhua Yao, Na Guo, Yuji He, Yu Xiao, Yang Li, Jianhua Gao, Yanjun Guo
更新时间: 2019-10-16
摘要: Aims: This study aims to evaluate the variations of soil organic matter and plant leaf cuticular waxes along an altitude gradient at two mountains in the east side of the Qinghai-Tibet Plateau. Methods: Surface soils were sampled along an altitude gradient (2600, 3000, 3400, 3800 and 4200 m). We analyzed the soil total organic carbon (TOC), dissolved organic carbon (DOC), soil lipids and leaf cuticular waxes in Kobresia humilis which distributed at all tested altitudes. Results: A sharp concentration increase of TOC was observed when altitudes increased, whereas the proportions of DOC in TOC at low altitudes (3000 m and 2600 m) were significantly higher than those at higher altitudes. Altitudes also influenced the molecular weight, humification degree, aromaticity, and hydrophobicity of DOC molecular. Though soils at higher altitudes relatively had higher abundance of odd carbon alkanes and even carbon alcohols, soil lipid concentrations showed no significant difference between altitudes. Relatively higher total wax coverage at high and low altitude was observed on leaves of K. humilis. Conclusions: The changes of altitudes at alpine ecosystem were associated with alterations of both quantity and quality of soil organic matter as well as leaf cuticular wax coverage, which contributed to their environmental adaptations.

24762. 题目: Sulfur-based mixotrophic bio-reduction for efficient removal of chromium (VI) in groundwater
文章编号: N19101601
期刊: Geochimica et Cosmochimica Acta
作者: Baogang Zhang, Zhongli Wang, Jiaxin Shi, Hailiang Dong
更新时间: 2019-10-16
摘要: Organic matter and reduced sulfur compounds commonly coexist in groundwater aquifers and their respective roles in Cr(VI) bio-reduction have been well established, but Cr(VI) bio-reduction under mixotrophic condition, where organics and elemental sulfur simultaneously occur as co-donors of electrons, remains largely unknown. Herein a sulfur-based mixotrophic bio-reduction process is demonstrated to be effective to detoxify Cr(VI), with a removal efficiency of 95.5 ± 0.74% within 48 h at an initial concentration of 50 mg/L. In addition to direct reduction by heterotrophic Cr(VI) reducers such as Desulfovibrio and Desulfuromonas, volatile fatty acids (VFAs) produced from autotrophic sulfur oxidation served as electron donors for heterotrophic Cr(VI) reducers. Part of VFAs was also assimilated and accumulated as glycogen within cells, which enhanced their Cr(VI) removal capacity. Metabolic pathway analysis suggested that Cr(VI) was reduced to insoluble Cr(III) both extracellularly by cytochrome c and intracellularly by nicotinamide adenine dinucleotide in the presence of upregulated chrA gene. Constituents of extracellular polymeric substances (EPS) also contributed to Cr(VI) reduction enzymatically, through binding of toxic Cr(VI) by carboxyl and hydroxyl groups. Results from this study have important implications for understanding the biogeochemical behavior and environmental remediation of Cr(VI) in groundwater aquifers and sediments/soils.

24763. 题目: Effect of organic matter release from natural cork used on bisphenol a removal from aqueous solution
文章编号: N19101507
期刊: Journal of Cleaner Production
作者: Carla Pirozzi, Ludovico Pontoni, Massimiliano Fabbricino, Anna Bogush, Luiza C. Campos
更新时间: 2019-10-15
摘要: The paper presents an experimental study aimed at investigating the mechanism responsible for Bisphenol A adsorption on natural cork, and the role played on process kinetics by the organic matter released from the cork. Obtained data show that natural cork has a good affinity toward Bisphenol A, with removal efficiency being as high as 75% in less than 24 h. The adsorption process is characterized by a fast-initial rate which tends to reduce progressively, and follows a pseudo second order model equation. Statistical physics analysis allows for obtaining a molecular description of the adsorption, which is shown to take place through a single anchorage point, perpendicularly to the adsorbent surface. Nuclear magnetic resonance spectroscopy and fluorescence analysis reveal that the colloidal organic matter released from the cork interacts with Bisphenol A; it also plays a relevant role in the slowing down of the adsorption rate, as it competes with cork adsorption sites for Bisphenol A. Organic matter is found to be highly heterogenous, presenting at the same time carbohydrates, aromatic and aliphatic domains. Such moieties interact stably with the contaminant in the solution probably due the establishment of dispersive forces (e.g. π-stacking) which sequestrate Bisphenol A into the inner hydrophobic core of the organic matter three-dimensional structure.

24764. 题目: Application of the eco-friendly bio-anode for ammonium removal and power generation from wastewater in bio-electrochemical systems
文章编号: N19101506
期刊: Journal of Cleaner Production
作者: Ali Reza Rahmani, Nahid Navidjouy, Mostafa Rahimnejad, Davood Nematollahi, Mostafa Leili, Mohammad Reza Samarghandi, Saber Alizadeh
更新时间: 2019-10-15
摘要: In this new insight, the potential application of the eco-friendly bioanode material was investigated with the aim of ammonium removal and its recovery, alongside power generation from wastewater in bio-electrochemical systems (BESs). In this procedure, biodegradation of ammonia was directly accrued via bioanode compartment driven by in-situ generated bioelectricity. To this end, this protocol was implemented with the anaerobic microbial as a biocatalyst in an anode chamber, as well as aerobic cathode chamber and a Nafion117 membrane as a separator with attractive results for the BES. The findings of the study suggested that BES, at the optimum operational conditions, can be an effective process for removing the high concentrations of organic materials and ammonium from industrial wastewater. The maximum BES efficiency was obtained 94% for the ammonium removal with a chemical oxygen demand (COD) concentration of 10,000 mg/L and a maximum organic removal rate of 78% with a substrate concentration of 2000 mg/L. The maximum voltage, power and current density of the BES was 481 mV, 62.7 mW/m2, 570 mA/m2, respectively. Further, an increase in NH4Cl concentration improved the maximum current density (808 mA/m2). The results demonstrated that the bio-electrochemical system could be utilized to treat industrial wastewater, containing high amounts of ammonium and organic materials, by adjusting the organic matter to ammonium (COD/NH4+) ratio while simultaneously generating electricity. Generally, the application of this eco-design, and sustainable bioanode material can be a good foundation and new perspective for practical application with regards to green and sustainable chemistry.

24765. 题目: The effect of low frequency ultrasonic treatment on the release of extracellular organic matter of Microcystis aeruginosa
文章编号: N19101505
期刊: Chemical Engineering Journal
作者: Yang-Rui Huang, Huai-Zheng Li, Xin-Min Wei, Deng-Hui Wang, Yu-Ting Liu, Lei Li
更新时间: 2019-10-15
摘要: The effect of low frequency ultrasonic treatment on the growth of cyanobacteria and the behavior of extracellular organic matter (EOM) were investigated in this study. The growth of cyanobacteria can be controlled effectively by low frequency ultrasonic treatment, and the inhibitory effect of ultrasound on the photosynthetic ability of cells was more significant than on the cells density (the minimum values of cells density and chlorophyll-a was obtained at day 3 and day 1 respectively). Significant rupture of cells was observed when irradiated by a higher intensity ultrasound (ultrasonic dosage ≥ 1.5 J/mL). Tyrosine-like components were mainly distributed in the soluble EOM and loosely bound EOM fractions; both of the tryptophan-like components and polyaromatic humic-like components were distributed in the soluble EOM, loosely bound EOM, and tightly bound EOM fractions; and polycarboxylate humic-like components were mainly distributed in soluble EOM fraction. Given that the production of hydroxyl radicals was measured, negligible due to the limit of ultrasonic treatment duration (≤ 1min). On the other hand, intensive shock waves and shear forces of collapsing acoustic cavitation bubbles were considered as the main reason for the rupture of cells and the changes of the behavior of EOM. A higher intensity ultrasonic treatment resulted in a greater release of EOM, including bound EOM (ultrasonic dosage ≥ 0.1 J/mL), and intracellular organic matter (ultrasonic dosage ≥ 1.5 J/mL). Moreover, the determination of protein and polysaccharide suggested that the bonding of polysaccharides to cells surface is stronger than that of proteins to cells surface, and a portion of the polysaccharides in other fractions was transferred to the tightly bound state during the first serval days after ultrasonic treatment.
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24766. 题目: Soil properties and rate of organic matter decomposition in riparian woodlands using the TBI protocol
文章编号: N19101504
期刊: Geoderma
作者: Diane Saint-Laurent, Lisane Arsenault-Boucher
更新时间: 2019-10-15
摘要: This study deals with the decomposition rates of two types of commercial teas (green and rooibos) using the protocol proposed by Keuskamp et al. (2013). The tea bag samples were distributed at 60 sites along two major rivers (Coaticook and Massawippi) in south-central Québec (Canada). The sampling sites were distributed in keeping with two separate zones: flood zones (FZ) (interval recurrence of 0–20 years) and no-flood zones (NFZ). Several soil and environmental parameters were included in the analysis of the tea bag samples, including soil acidity, total organic carbon and total nitrogen content, texture, litter thickness (cm), drainage and topography. The green tea samples were found to decompose twice as fast as the rooibos tea samples under similar soil and environmental conditions. The remaining green tea mass showed average values of 23 and 34% for the FZ in the Coaticook (COA) and Massawippi (MAS) areas, and 32 and 30% for the NFZ in the same two areas. The average values for the rooibos tea samples were 62 and 60% (FZ), and 62 and 61% (NFZ), respectively. The decomposition rate (k) and stabilization factor (S) for the tea bag samples are comparable between zones (FZ and NFZ) and between areas (COA and MAS), with values ranging from 0.020 ± 0.01 to 0.030 ± 0.01 g·g⁻¹·day⁻¹ (k), and from 0.165 ± 0.08 to 0.218 ± 0.05 g·g⁻¹·day⁻¹ (S). Based on the results obtained, the S and k variables were not correlated with any soil and environmental variables, and the statistical analyses did not yield any significant differences (p-value 0.05). By grouping various soil and environmental parameters with the analysis of the decomposition of the tea bag samples, these parameters were seen to have little influence, and the nature of the organic compounds (higher or lower litter quality) appears to be the main factor in determining the decomposition rate.

24767. 题目: Divergent responses of soil bacterial communities in erosion-deposition plots on the Loess Plateau
文章编号: N19101503
期刊: Geoderma
作者: Lanlan Du, Rui Wang, Xin Gao, Yaxian Hu, Shengli Guo
更新时间: 2019-10-15
摘要: Soil erosion and deposition occur widely from regional to global scales and have profound impacts on ecological services and sustainability. Despite their crucial roles in biogeochemical cycles, the responses of soil bacterial communities to soil erosion and deposition remain largely unclear. In this study, a field simulation experiment was conducted to examine variation in soil bacterial communities across eroding slopes and depositional zones with three slope gradients (5°, 10° and 20°) on the Loess Plateau of China (2015–2017). The results showed that soil physicochemical properties were altered by redistribution of runoff and sediment across eroding slopes and depositional zones. Soil bacterial alpha diversity was higher in the depositional zones of both 10° and 20° slopes compared with the 5° reference slopes but no markedly difference was found between eroding slopes and reference slopes. By contrast, bacterial community structure differed between eroding slopes and reference slopes but not between depositional zones and reference slopes. Differentiation of bacterial communities between eroding slopes and depositional zones increased with increasing slope gradients. The bacterial network was greater and more complex within depositional zone than eroding slope, indicating more extensive bacterial interactions and greater community stability potential. Erosion- and deposition-induced redistribution of soil moisture, soil organic matter, available P, and available K were the key determinants of variation in bacterial community structure. Our findings demonstrate the contrasting effects of soil erosion and deposition on soil bacterial communities, which should be given further attention across eroding landscapes.

24768. 题目: Use of humic substances in froth flotation processes
文章编号: N19101502
期刊: Journal of Environmental Management
作者: Lorenzo Reyes-Bozo, Eduardo Vyhmeister, Alex Godoy-Faúndez, Pablo Higueras, Carlos Fúnez-Guerra, Héctor Valdés-González, José Luis Salazar, Ronaldo Herrera-Urbina
更新时间: 2019-10-15
摘要: Continual growing demand for metals in regular and emerging markets has led to an increasing use of chemicals and reagents in ore processing. This trend force to incur in an increasing use of commodities which inevitable leads to higher operational costs and environmental concern. The chemicals and reagents used in flotation processes especially invoke high costs of handling and disposal due to their hazardous nature, but until now, few studies have been carried out to seek possible alternatives. In order to develop a cheaper and greener processes, these hazardous materials should be replaced by more sustainable products, by-products, or wastes generated by other industries. Biosolids, cheaper and greener than chemical frothers and collectors, have been tested successfully in flotation processes. Studies of removal rates and froth flotation kinetics have been carried out independently, nevertheless a deeper understanding of the tradeoffs involved between the rates and kinetics should be obtained. This work evaluates the use of different collectors (conventional collector (CC), biosolids (and their main components), and mixtures of CC and biosolids main components) in the froth flotation of copper sulfide ores. Tests were carried out in Denver Cells, at fixed collector, frother, and pH levels, in order to estimate metallurgical and kinetic parameters. In rougher flotation tests, biosolids show to be the most efficient non-CCs, achieving Cu recoveries of 64.1%. CC achieved 76.2% Cu recoveries while none of the pure biosolids main components achieved Cu recoveries over 60%. In the kinetics studies, only the partial replacement of CC (by 50% of Humic Acids (HAs) or biosolids) allowed a similar copper recovery once compared with CC (~81% Cu to be obtained with a fast kinetic constant of ~0.88 min⁻¹). For molybdenum, partial replacement of CC produced better recovery and kinetics constants (k of 0.83 min⁻¹ and R_∞ of 66.10% for 50% CC - 50% HAs; k of 0.90 min⁻¹ and R_∞ of 61.79% for 50% CC - 50% biosolids). Results show that different combinations of biosolids - CC or HAs - CC could achieve optimal flotation conditions. As evaluated, an optimal combinations would allow considerable reductions in energy and chemical consumption.

24769. 题目: Kinetics of oil generation from brackish-lacustrine source rocks in the southern Bohai Sea, East China
文章编号: N19101501
期刊: Organic Geochemistry
作者: Haoran Liang, Fanghao Xu, Kliti Grice, Guosheng Xu, Alex Holman, Peter Hopper, Deliang Fu, Qing Yu, Jiaju Liang, Deying Wang
更新时间: 2019-10-15
摘要: Oil generation (C₁₄₊ hydrocarbons) of three Type II kerogen samples isolated from brackish-lacustrine mudstones from Palaeogene strata (Ed₃, Es₁, Es₃) in the southern Bohai Sea was simulated by closed-system gold tube experiments. In addition, a series of complementary analyses (Rock-Eval pyrolysis, total organic carbon, vitrinite reflectance, trace element, X-ray diffraction and flash pyrolysis-gas chromatography–mass spectrometry) were also performed to identify the bulk geochemistry, palaeo-environment and chemical composition of the kerogen. The aim of this study was to achieve a better understanding of the kinetics of oil generation from lacustrine source rocks in the southern Bohai Sea. The results show that the three samples are Type II source rocks deposited in similar palaeo-environments (hot and arid climates, anoxic conditions, and brackish water in shallow to semi-deep lakes) with consequent similarity in the chemical compositions of their kerogens. The organic matter inputs are predominantly composed of lacustrine microalgae, with a relatively small contribution from land plants. The activation energies of oil generation from these samples show a range of 44–52 kcal/mol, with a frequency factor varying from 1.116×10¹⁴ to 1.274×10¹⁴ s^-1. Due to the similar palaeo-environments and chemical composition, samples in this study exhibit strong consistencies in kinetic parameters. Transformation ratio (TR) evolution curves of oil generation from the three samples, calculated under a linear heating rate (3 K/Ma), exhibit a slight difference, which varies within 4 °C at a given TR. Due to the great similarities of the three kinetic models, an average kinetic model for the Type II brackish-lacustrine source rocks in the southern Bohai Sea was established. This model integrates the characteristics of the three kinetic models and is still dominated by activation energy of 52 kcal/mol. The geological temperature of the oil generation phase for the average model in the southern Bohai Sea is from 92–137 °C.

24770. 题目: The first deep-sea mooring station in the eastern Levantine basin (DeepLev), outline and insights into regional sedimentological processes
文章编号: N19101402
期刊: Deep Sea Research Part II: Topical Studies in Oceanography
作者: Timor Katz, Yishai Weinstein, Ronen Alkalay, Eli Biton, Yaron Toledo, Ayah Lazar, Olga Zlatkin, Rotem Soffer, Eyal Rahav, Guy Sisma-Ventura, Tslil Bar, Tal Ozer, Hezi Gildor, Ahuva Almogi-Labin, Mor Kanari, Ilana Berman-Frank, Barak Herut
更新时间: 2019-10-14
摘要: The eastern Levantine basin (ELB) is an ultra-oligotrophic, warm and saline marine system, significantly affected by climate change during the past several decades. The deployment of the first moored station at the ELB (DeepLev), at 1500 m water depth, ∼50 km offshore Haifa, Israel, aimed at enhancing synchronized measurements of physical and biogeochemical dynamics. The station carries an array of sediment traps and sensors that measure physical, chemical, and biological attributes along the water column. Here we describe the station and present sediment-flux data from the first 1.5 years of operation (since November 2016). We show that, despite DeepLev's offshore location and the open-sea characteristics of the water column, lateral transport from the continental margin contributes the greatest fraction of particulate flux to the seafloor at this site. This mostly occurs via intermediate nepheloid layer plumes entering the study area between depths of 180 and 800 m. Bottom currents are weak (average ± SD = 3.5 ± 2 cm s−1) and are unlikely to cause significant resuspension. Based on sedimentation rates obtained from nearby sediment cores and sediment particle fluxes sampled in the traps, calculated accumulation rates of total particulate matter and of particulate organic carbon at the seafloor were 95–108 g m−2 y−1 and 0.5–0.6 g m−2 y−1, respectively. Offshore changes in sedimentation rates and in surface sediment elemental ratios indicate that sediment originating from the continental margins is transported at least 100 km offshore.

24771. 题目: Temperature-dependent mechanisms of DOM removal by biological activated carbon filters
文章编号: N19101401
期刊: Environmental Science: Water Research & Technology
作者: Nashita Moona, Urban Wünsch, Mia Bondelind, Olof Bergstedt, Tugba Sapmaz, Thomas J. R. Pettersson, Kathleen Murphy
更新时间: 2019-10-14
摘要: Seasonal variability in the removal of dissolved organic matter (DOM) by drinking water biological activated carbon (BAC) filters is often attributed to temperature changes. However, it can be rather difficult to directly relate temperature to treatment efficiency at full scale due to seasonal variations in other influential parameters like DOM concentration and character, and microbial activity. Furthermore, processes in BAC filters include adsorption, desorption and biodegradation within biofilms while each respond differently to temperature. This study aimed to decouple these processes by studying the removal of various DOM fractions from coagulated and settled drinking water when in contact with aged (>3 years) BAC filter material at different water temperatures. DOM removal was measured as changes in dissolved organic carbon (DOC), ultraviolet absorbance at 254 nm (UV254) and fluorescence. Under the particular experimental conditions there was little evidence of biological removal; instead, removal of DOM fractions emitting at longer wavelengths (“humic-like”, > 430 nm) was consistent with chemisorption, removal of DOM emitting at intermediate wavelengths (“humic-like”, 390 - 420 nm) was consistent with physisorption, and multiple mechanisms were indicated for “protein-like” (<380 nm) DOM. Non-biological mechanisms of DOM removal by aged BAC filters are often assumed to be unimportant; however, these results suggest they are important for some DOM fractions, especially during periods of reduced microbial activity.

24772. 题目: Removal of lead from acidic wastewater by bio-mineralized bacteria with pH self-regulation
文章编号: N19101314
期刊: Chemosphere
作者: Kejing Zhang, Yingwen Xue, Jiaqi Zhang, Xiaolan Hu
更新时间: 2019-10-13
摘要: Microorganisms with the function of bio-mineralization were isolated from a soil. They were identified as urease-producing bacteria and phosphate-solubilizing bacteria. These two kinds of bacteria belong to the eosinophilic bacteria, which regulated the pH of solution and removed Pb²⁺ the best at the initial solution pH of 4. The Pb²⁺ removal mechanism was further explored using various techniques including zeta potential measurement, three-dimensional fluorescence, FTIR, XRD, and TEM-EDS. The results showed that extracellular adsorption, intracellular accumulation and bio-mineralization occurred at the same time and converted to each other. The extracellular adsorption of urease-producing bacteria was through electrostatic adsorption and gradually decomposed urea to produce PbCO₃ minerals. The extracellular adsorption of phosphate-solubilizing bacteria was controlled by extracellular polymeric substances (EPS) and rapidly formation of Pb₃(PO₄)₂ stable minerals. In addition, the stabilities of Lead minerals of the two strains were compared. The results showed that the precipitates of phosphate-solubilizing bacteria were more stable. While phosphate-solubilizing bacteria have some advantages, both strains can play important roles in bio-mineralization of HMs in acidic wastewater.
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24773. 题目: Comparison of humic and fulvic acid on remediation of arsenic contaminated soil by electrokinetic technology
文章编号: N19101313
期刊: Chemosphere
作者: Jiangpeng Li, Ying Ding, Kaili Wang, Ningqing Li, Guangren Qian, Yunfeng Xu, Jia Zhang
更新时间: 2019-10-13
摘要: The use of humic acid (HA) and fulvic acid (FA) as reinforcing agents to improve the efficiency of electrokinetic remediation (EKR) were investigated for the first time using an artificially contaminated soil. A series of soil leaching tests and bench-scale EKR experiments were performed to elucidate the mechanisms of As removed from artificially contaminated soil. The characterization of total reducing capacity (TRC) and functional group were carried out to reveal the difference of HA and FA. The observations demonstrated that with 0.1 M NaOH and KCl as the anolyte, using both HA and FA enhanced the efficiency of EKR. After 25 days of EKR, the removal efficiency of TAs in HA/FA-enhanced EKR was about 2.0–3.0 times greater than when unenhanced. Compared to HA, more As was removed in EKR with FA, which has more TRC and oxygen-containing groups. These EKR experimental results, with the support of data obtained from soil leaching test, indicate that competitive adsorption, reductive dissolution and complexation were the reasons why HA and FA promoted the release of As in the soil and further enhanced the remediation efficiency.
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24774. 题目: Sb(III)-resistance mechanisms of a novel bacterium from non-ferrous metal tailings
文章编号: N19101312
期刊: Ecotoxicology and Environmental Safety
作者: Jihai Gu, Geoffrey Sunahara, Robert Duran, Jun Yao, Yongqiang Cui, CengCeng Tang, Hongquan Li, Victor G. Mihucz
更新时间: 2019-10-13
摘要: Understanding the mechanism(s) of microbial resistance to antimony (Sb) is critical in the bioremediation of Sb polluted environments. Here a novel bacterium (Acinetobacter sp. JH7) isolated from mine tailings decreased the Microtox toxicity of a Sb(III)-containing medium. DNA sequencing and physiological testing were employed for the identification and characterization of strain JH7. Following a batch experiment, Fourier transform infrared spectroscopy (FTIR) and antimony speciation analyses determined the adsorption and oxidation of antimony. Analyses of Sb(III) distribution revealed that extracellular polymeric substances and cell walls inhibited Sb(III) entry into JH7 cells. FTIR studies indicated that key functional groups including –OH, C–N, and C–O likely participated in Sb(III) biosorption. Isothermal and kinetic studies revealed that Sb(III) sorption to viable JH7 cells fitted the Langmuir model (R² = 0.99) and could be described by pseudo-second order kinetics (R² = 0.99). Furthermore, the increase of anti-oxidative enzymatic activity of JH7 enhanced the intracellular detoxification of Sb(III), which would indirectly contribute to the Sb(III) resistance ability of strain JH7. Our results indicate that biosorption and ROS oxidation of Sb(III) were likely responsible for the decreased toxicity of Sb. The greater understanding how Acinetobacter sp. JH7 lowers the environmental Sb(III) toxicity could provide a basis for future research and subsequent development of technologies for the remediation of Sb contaminated sites.
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24775. 题目: The potential of microplastics as carriers of metals
文章编号: N19101311
期刊: Environmental Pollution
作者: V. Godoy, G. Blázquez, M. Calero, L. Quesada, M.A. Martín-Lara
更新时间: 2019-10-13
摘要: Microplastics can adsorb chemical pollutants such as metals or pharmaceuticals, and transferred them along the food chain. In this work, an investigation of the adsorption of Cd, Co, Cr, Cu, Ni, Pb and Zn by five different types of microplastics was performed in Milli-Q water and natural waters (seawater, urban wastewater and irrigation water) via a series of batch adsorption experiments. The effects of concentration of metals and physicochemical characteristics of polymers were particularly studied. Results revealed a significant adsorption of lead, chromium and zinc on microplastics, especially on polyethylene and polyvinyl chloride. In the case of polyethylene terephthalate, it showed little adsorption capacity. Specific surface, porosity and morphology are characteristics that affect the molecular interactions. The adsorption isotherms were better described by Langmuir model, which indicates that the main adsorption mechanism might be chemical adsorption. Finally, results obtained in natural waters indicated that dissolved organic matter may play a major role on metal adsorption on microplastics. Results showed an enhancement of metal adsorption in waters with high chemical and biological oxygen demands as urban wastewater and irrigation water.
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24776. 题目: PM2.5-induced extensive DNA methylation changes in the heart of zebrafish embryos and the protective effect of folic acid
文章编号: N19101310
期刊: Environmental Pollution
作者: Yan Jiang, Jianxiang Li, Fei Ren, Cheng Ji, Stanley Aniagu, Tao Chen
更新时间: 2019-10-13
摘要: We previously found that folic acid (FA) attenuated cardiac defects in zebrafish embryos exposed to extractable organic matter (EOM) from PM2.5, but the underlining mechanisms remain to be elucidated. Since DNA methylation is crucial to cardiac development, we hypothesized that EOM-induced aberrant DNA methylation changes could be diminished by FA supplementation. In this study, zebrafish embryos were exposed to EOM in the absence or presence of FA. Genomic-wide DNA methylation analysis identified both DNA hypo- and hyper-methylation changes in CCGG sites in zebrafish embryos exposed to EOM, which were attenuated by FA supplementation. We identified a total of 316 genes with extensive DNA methylation changes in EOM samples but little or no DNA methylation changes in EOM plus FA samples. The genes were involved in critical cellular processes and signaling pathways important for embryo development. In addition, the EOM-decreased SAM/SAH ratio was counteracted by FA supplementation. Furthermore, FA attenuated the EOM-induced changes in the expression of genes involved in the regulation of DNA methylation and in folate biosynthesis. In conclusion, our data suggest that FA supplementation protected zebrafish embryos from the cardiac developmental toxicity of PM2.5 by alleviating EOM-induced DNA methylation changes.
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24777. 题目: Diurnal carbon dynamics in a mangrove-dominated tropical estuary (sundarbans, India)
文章编号: N19101309
期刊: Estuarine, Coastal and Shelf Science
作者: Manab Kumar Dutta, Sanjeev Kumar, Rupa Mukherjee, Niharika Sharma, Avanti Acharya, Prasun Sanyal, Ravi Bhusan, Sandip Kumar Mukhopadhyay
更新时间: 2019-10-13
摘要: Based on a 24h of time-series study, we report the effects of a tidal cycle on carbon biogeochemistry of a mangrove dominated tropical estuary (the Sundarbans) located in the eastern part of India. Salinity, dissolved oxygen, and pH showed clear tidal variability with relatively higher values during high tide than low tide. Dissolved inorganic carbon (DIC) concentrations varied over a narrow range (1.92–2.19 mM) with relatively higher values during low tide; reverse trend, however, was noticed for δ¹³C_DIC with significant variability (– 4.28 to – 2.21‰). During low tide, along with estuarine mixing, preliminary evidences for influences of biogeochemical (such as organic carbon mineralization, sulfate reduction, and denitrification) and hydrological processes (porewater exchange) were found on DIC dynamics. The δ¹³C_DIC - DIC relationship suggested respiration of marine plankton to be one of the possible sources for DIC. Dissolved organic carbon showed tidal influence during high tide with a signal of porewater mediated addition during low tide. Both particulate organic carbon and particulate nitrogen concentrations reached the maximum during low tide with stable isotopic compositions showing predominantly marine signature along with the possibility of biogeochemical modifications within the estuary. Marine water contribution together with organic carbon mineralization and possible porewater influx resulted in ∼214 μatm higher pCO₂ and 1.13 times higher FCO₂ during low tide than high tide. On diurnal basis, the estuary released ∼1348 mg CO₂ per m² of surface area to the regional atmosphere.

24778. 题目: Removal mechanisms of aqueous Cr(VI) using apple wood biochar: a spectroscopic study
文章编号: N19101308
期刊: Journal of Hazardous Materials
作者: Na Liu, Yuting Zhang, Chao Xu, Peng Liu, Jing Lv, YingYing Liu, Qiaoying Wang
更新时间: 2019-10-13
摘要: Highly toxic Cr(VI) poses huge threats to human health and ecosystem. This study utilized biochar obtained from apple wood which is favorable for the formation of high C content biochar for removing Cr(VI) from aqueous media. Cr(VI) removal was highly pH-dependent with the highest Cr(VI) removal efficiency (99.9%) at pH 2.0. Fourier-transform infrared spectroscopy (FTIR) results showed that the functionalities CO and CO on biochar were likely involved in Cr(VI) treatment. Results of X-ray photoelectron spectroscopy (XPS) analysis and X-ray absorption near-edge structure (XANES) spectra indicated that the majority of Cr exhibited as the reduced Cr(III) on the biochar. Confocal micro X-ray fluorescence (μ-XRF) maps confirmed the heterogeneous distribution of Cr on biochar. The electrostatic attraction, Cr(VI) reduction, Cr(III) complexation, and ion exchange likely accounted for the principal processes of Cr(VI) removal from water. These results showed that biochar can be an effective reactive medium for remediation of Cr(VI) in an aqueous solution. This study firstly integrated the Cr(VI) removal data with XANES and confocal μ-XRF mapping to obtain a deeper understanding of Cr speciation and distribution on biochar, which was critical for identifying the key role of functional groups and Cr(VI) removal mechanisms using apple wood biochar.

24779. 题目: Impacts of nitrogen management and organic matter application on nitrous oxide emissions and soil organic carbon from spring maize fields in the North China Plain
文章编号: N19101307
期刊: Soil and Tillage Research
作者: Naijie Chang, Zhen Zhai, Hu Li, Ligang Wang, Jia Deng
更新时间: 2019-10-13
摘要: Soil carbon dioxide (CO₂) and nitrous oxide (N₂O) emissions and carbon (C) sequestration are important processes for determining net greenhouse gas (GHG) emissions from maize fields. Farming management practices (FMPs) substantially affect crop productivity, soil organic carbon (SOC), and N₂O emissions. However, relative knowledge is not sufficient, and further research is required for sustainable agriculture development. A multi-year experiment was performed on a spring maize field in the North China Plain (NCP) to quantify changes in SOC stocks, N₂O emissions, and maize yields. Seven treatments were involved in the experiment, including no N fertilization (CK), farmers’ conventional N fertilization (FP), sole application of manure N (M), a combination of M and FP (MFP), FP combined with returned maize straw (SFP), fertilization with reduced synthetic N amount (RN), and fertilization with both reduced synthetic and manure N (RMN). The field measurements demonstrated that urea applications and returned maize straw increased N₂O emission. The seasonal total N₂O emissions under FP were significantly (P < 0.05) higher than those under CK by 176% to 222% and lower than those under SFP by 20% to 61% throughout the three maize growing seasons. The application of organic manure or maize straw enhanced SOC storage for the studied cropping system. The SOC stocks were relatively high in the plots that received applications of organic manure or maize straw, with the SOC stock of the M plot being significantly higher (P < 0.05) than that of the CK, FP, SFP, RN, and RMN plots in 2016 after eight years of manure amendments. The average net GHG emission from 2012 to 2014 was 203 kg CO₂ equivalent ha⁻¹ year⁻¹ (i.e., a net GHG source) under FP. The other treatments converted the maize fields from net GHG sources to GHG sinks. By considering both the maize yields and net GHG emissions, RMN would be an optimal management option, although MFP, SFP, and RN also mitigated the GHG emissions and maintained the yields. Large variations were observed in the contributions of the SOC changes and N₂O emissions to net GHG emissions among the treatments. The large variations demonstrate the need to consider both SOC changes and N₂O emissions when evaluating the impacts of alternative FMPs on net GHG emissions.

24780. 题目: Constructing zwitterionic polymer brush layer to enhance gravity-driven membrane performance by governing biofilm formation
文章编号: N19101306
期刊: Water Research
作者: Caihong Liu, Dan Song, Wenjuan Zhang, Qiang He, Xiaoliu Huangfu, Shaofang Sun, Zhiqiang Sun, Wei Cheng, Jun Ma
更新时间: 2019-10-13
摘要: In this study, zwitterionic polymer brushes with controlled architecture were grafted on the surface of gravity-driven membrane (GDM) via surface-initiated reaction to impart antifouling property. A variety of membrane characterization techniques were conducted to demonstrate the successful functionalization of zwitterionic polymers on PVDF hollow fiber membrane. The membrane underwent 90 min of reaction time possessing strong hydrophilicity and high permeability was determined as the optimal modified membrane. Long-term GDM dynamic fouling experiments operated for 30 days using sewage wastewater as feed solution indicated zwitterionic polymer modified membrane exhibit excellent membrane fouling resistance thus enhanced stable flux. Confocal laser scanning microscopy (CLSM) imaging implied that zwitterionic polymer modification significantly inhibit the adsorption of extracellular polymeric substances (EPS) which dominates fouling propensity, resulting in the formation of a thin biofilm with high porosity under synthetic functions of foulants deposition and microbial activities. Interfacial free energy prediction affirmed the presence of zwitterionic functional layer on membrane surface could substantially decrease the interactions (e.g., electrostatic attractions and hydrophobic effects) between membrane and foulants, thereby reduced flux decline and high stable flux. Our study suggests surface hydrophilic functionalization shows promising potential for improving the performance of ultra-low pressure filtration.
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