Pd-MnO2 nanoparticles/TiO2 nanotube arrays (NTAs) photo-electrodes photo-catalytic properties and their ability of degrading Rhodamine B under visible light

Pd-MnO_2/TiO_2 nanotube arrays(NTAs) photo-electrodes were successfully fabricated via anodization and electro deposition subsequently; the obtained Pd-MnO_2/TiO_2 NTAs photo electrodes were analyzed by scanning electron microscopy(SEM), X-ray diffraction(XRD) and characterized accordingly. Moreover, the light harvesting and absorption properties were investigated via ultraviolet–visible diffuse reflectance spectrum(DRS); photo degradation efficiency was investigated via analyzing the photo catalytic degradation of Rhodamine B under visible illumination(xenon light). The performed analyses illustrated that Pd-MnO_2 codoped particles were successfully deposited onto the surface of the TiO_2 nanotube arrays;DRS results showed significant improvement in visible light absorption which was between400 and 700 nm. Finally, the photo catalytic degradation efficiency results of the designated organic pollutant(Rhodamine B) illustrated a superior photocatalytic(PC) efficiency of approximately 95% compared to the bare TiO_2 NTAs, which only exhibited a photo catalytic degradation efficiency of approximately 61%, thus it indicated the significant enhancement of the light absorption properties of fabricated photo electrodes and their yield of UOH radicals.     

Effect of barium sulfate modification on the SO2 tolerance of V2O5 /TiO2 catalyst for NH3-SCR reaction

Sulfur poisoning of V_2O_5/BaSO_4–TiO_2(VBT),V_2O_5/WO_3–TiO_2(VWT) and V_2O_5/BaSO_4–WO_3–TiO_2(VBWT) catalysts was performed in wet air at 350℃ for 3 hr,and activities for the selective catalytic reduction of NO_x with NH_3 were evaluated for 200–500℃.The VBT catalyst showed higher NO_x conversions after sulfur poisoning than the other two catalysts.The introduction of barium sulfate contributed to strong acid sites for the as-received catalyst,and eliminated the redox cycle of active vanadium oxide to some extent,which resulted in a certain loss of activity.Readily decomposable sulfate species formed on VBT-S instead of inactive sulfates on VWT-S.These decomposable sulfates increased the number of strong acid sites significantly.Some sulfate species escaped during catalyst preparation and barium sulfate was reproduced during sulfur poisoning,which protects vanadia from sulfur oxide attachment to a great extent.Consequently,the VBT catalyst exhibited the best resistance to sulfur poisoning.     

Mesoporous carbon nanomaterials induced pulmonary surfactant inhibition, cytotoxicity, inflammation and lung fibrosis

Environmental exposure and health risk upon engineered nanomaterials are increasingly concerned. The family of mesoporous carbon nanomaterials(MCNs) is a rising star in nanotechnology for multidisciplinary research with versatile applications in electronics,energy and gas storage, and biomedicine. Meanwhile, there is mounting concern on their environmental health risks due to the growing production and usage of MCNs. The lung is the primary site for particle invasion under environmental exposure to nanomaterials. Here, we studied the comprehensive toxicological profile of MCNs in the lung under the scenario of moderate environmental exposure. It was found that at a low concentration of 10 μg/mL MCNs induced biophysical inhibition of natural pulmonary surfactant. Moreover, MCNs at similar concentrations reduced viability of J774 A.1 macrophages and lung epithelial A549 cells.Incubating with nature pulmonary surfactant effectively reduced the cytotoxicity of MCNs.Regarding the pro-inflammatory responses, MCNs activated macrophages in vitro, and stimulated lung inflammation in mice after inhalation exposure, associated with lung fibrosis.Moreover, we found that the size of MCNs played a significant role in regulating cytotoxicity and pro-inflammatory potential of this nanomaterial. In general, larger MCNs induced more pronounced cytotoxic and pro-inflammatory effects than their smaller counterparts. Our results provided valuable information on the toxicological profile and environmental health risks of MCNs, and suggested that fine-tuning the size of MCNs could be a practical precautionary design strategy to increase safety and biocompatibility of this nanomaterial.     

Influence of coagulation mechanisms and floc formation on filterability

Minimizing particles in water is a key goal for improving drinking water quality and safety.The media filtration process,as the last step of the solid–liquid separation process,is largely influenced by the characteristics of flocs,which are formed and controlled within the coagulation process.In a laboratory-based study,the impacts of the physical characteristics of flocs formed using aluminum sulfate on the filtration treatment of two comparative water samples were investigated using a photometric dispersion analyzer and a filterability apparatus.In general,the optimum dosage for maximizing filterability was higher than that for minimizing turbidity under neutral p H conditions.For a monomeric aluminum-based coagulant,the charge neutralization mechanism produced better floc characteristics,including floc growth speed and size,than the sweep flocculation mechanism.In addition,the charge neutralization mechanism showed better performance compared to sweep flocculation in terms of DOC removal and floc filterability improvement for both waters,and showed superiority in turbidity removal only when the raw water had high turbidity.For the different mechanisms,the ways that floc characteristics impacted on floc filterability also differed.The low variation in floc size distribution obtained under the charge neutralization mechanism resulted in the flocs being amenable to removal by filtration processes.For the sweep flocculation mechanism,increasing the floc size improved the settling ability of flocs,resulting in higher filter efficiency.     

Tissue distribution of perfluoroalkyl acids and health status in wild Mozambique tilapia (Oreochromis mossambicus) from Loskop Dam, Mpumalanga, South Africa

This study examined concentrations of 15 perfluoroalkyl acids (PFAAs) in tissues from male Mozambique tilapia (Oreochromis mossambicus) collected at Loskop Dam, Mpumalanga, South Africa in 2014 and 2016. Nine of the 15 PFAAs were detected frequently and were included in statistical analysis and included two of the most commonly known PFAAs, perfluorooctanesulfonic acid (PFOS) (median, 41.6 ng/g) and perfluorooctanoic acid (PFOA) (median, 0.0825 ng/g). Of the tissues measured, plasma (2016 and 2014 median, 22.2 ng/g) contained the highest PFAA burden followed by (in descending order): liver (median, 11.6 ng/g), kidney (median, 9.04 ng/g), spleen (median, 5.92 ng/g), adipose (median, 2.54 ng/g), and muscle (median, 1.11 ng/g). Loskop Dam tilapia have been affected by an inflammatory disease of the adipose tissue known as pansteatitis, so this study also aimed to investigate relationships between PFAA tissue concentrations and incidence of pansteatitis or fish health status. Results revealed that healthy tilapia exhibited an overall higher (p-value < 0.05) PFAA burden than pansteatitis-affected tilapia across all tissues. Further analysis showed that organs previously noted in the literature to contain the highest PFAA concentrations, such as kidney, liver, and plasma, were the organs driving the difference in PFAA burden between the two tilapia groups. Care must be taken in the interpretations we draw from not only the results of our study, but also other PFAA measurements made on populations (human and wildlife alike) under differing health status.     

Comparative mammalian cell cytotoxicity of wastewater with elevated bromide and iodide after chlorination, chloramination, or ozonation

Recycling wastewater is becoming more common as communities around the world try to better control their water resources against an increased frequency of either prolonged droughts or intense flooding. For communities in coastal areas, wastewaters may contain elevated levels of bromide(Br~-) and iodide(I~-) from seawater intrusion or high mineral content of source waters. Disinfection of such wastewater is mandatory to prevent the spread of pathogens, however little is known about the toxicity of wastewater after disinfection in the presence of Br~-and I~-. In this study we compared the induction of chronic cytotoxicity in mammalian cells in samples of municipal secondary wastewater effluent amended with elevated levels of Br~-/I~-after disinfection by chlorine, chloramines or ozone to identify which disinfection process generated wastewater with the lowest level of adverse biological response. Chlorination increased mammalian cell cytotoxicity by 5times as compared to non-disinfected controls. Chloramination produced disinfected wastewater that expressed 6.3 times more cytotoxicity than the non-disinfected controls and was 1.3 times more cytotoxic than the chlorinated samples. Ozonation produced wastewater with cytotoxicity comparable to the non-disinfected controls and was at least 4times less cytotoxic than the chlorine disinfected wastewaters. These results indicate that compared to chlorination and chloramination, ozonation of wastewater with high Br~-/Ilevels yielded the lowest mammalian cell cytotoxicity, suggesting its potential as a more favorable method to disinfect wastewater with minimizing the biological toxicity in mind.     

Sensitivity of Precipitation Statistics to Urban Growth in a Subtropical Coastal Megacity Cluster

This short paper presents an investigation on how human activities may or may not affect precipitation based on numerical simulations of precipitation in a benchmark case with modified lower boundary conditions, representing different stages of urban development in the model. The results indicate that certain degrees of urbanization affect the likelihood of heavy precipitation significantly, while less urbanized or smaller cities are much less prone to these effects. Such a result can be explained based on our previous work where the sensitivity of precipitation statistics to surface anthropogenic heat sources lies in the generation of buoyancy and turbulence in the planetary boundary layer and dissipation through triggering of convection. Thus only mega cities of sufficient size, and hence human-activity-related anthropogenic heat emission, can expect to experience such effects. In other words, as cities grow, their effects upon precipitation appear to grow as well.     

锑胁迫下丛枝菌根真菌对玉米生长与锑吸收及抗氧化酶的影响

为了探讨AM(arbuscular mycorrhizal,丛枝菌根)真菌在Sb(锑)胁迫下对农作物生长及吸收Sb的影响,采用盆栽试验研究了在不同Sb添加量[即w(Sb)分别为0、500、1 000 mg/kg]下,接种AM真菌对玉米植株生物量以及N、P和Sb的吸收、膜脂过氧化[MDA(丙二醛)]和抗氧化酶活性的影响.结果表明:随着土壤中Sb添加量的增加,玉米植株的生物量、w(TN)和w(TP)均呈显著下降趋势,植株体内的w(Sb)和Sb积累量、MDA含量、CAT(过氧化氢酶)以及POD(过氧化酶)活性均显著上升.与未接种组相比,接种AM真菌显著促进了玉米植株的生长,提高了玉米植株地上部分的w(TN)和w(TP).在3个Sb添加量处理下,接种显著增加了玉米植株地下部分的w(Sb)、地上和地下部分的Sb积累量以及地上部分的CAT活性,增幅分别为8.90%~23.30%、18.87%~28.37%、27.68%~78.95%及14.92%~88.52%;同时,接种降低了玉米植株中Sb的转运率、玉米植株地上部分的w(Sb)和MDA含量,在1000 mg/kg Sb添加量下差异达显著水平,三者分别降低了36.35%、22.81%和24.29%.研究显示,在Sb污染环境下,接种AM真菌能够减轻玉米植株膜脂过氧化程度,在提高玉米植株地下部分w(Sb)的同时,也会降低Sb向地上部分的转运,减轻Sb对玉米的毒害作用.      

三江源区生态系统状况变化及其成因

三江源区是黄河、长江和澜沧江的发源地.为研究三江源区生态系统状况变化及其可能成因,利用InVEST（Integrate Valuation of Ecosystem Services and Tradeoffs）、CASA（Carnegie-Ames-Stanford Approach）、RUSLE（Revised Universal Soil Loss Equation）和RWSQ（Revised Wind Erosion Equation）模型模拟,结合实地观测数据,系统全面地评估2000年以来三江源区生态系统构成、质量和服务功能变化,并揭示其成因.结果表明:① 2000—2010年三江源区生态系统结构基本稳定.草地退化状况轻微好转,产草量和生产力微弱增加.植被生长季水热条件的改善是促使产草量增加和草地退化态势趋缓的重要原因,同时生态工程的实施也发挥了积极作用.② 2005—2010年局部重点生态工程区的水土流失状况轻微好转,但区域整体好转趋势不明显.土壤中w（有机质）明显增加,但对于土壤保持功能起到关键作用的植被根系层的恢复却比较缓慢,降雨侵蚀力的增强加速了土壤侵蚀过程,生态系统的土壤保持功能基本上没有提高.③ 2000—2013年地表水、地下水资源量和土壤湿度均呈明显增加趋势,水质稳定在GB 3838—2002《地表水环境质量标准》划定的Ⅰ~Ⅱ类.降水量和冰川/积雪融水量增加导致径流量增大,气候变暖引起的冻土退化导致地下水库枯水季径流调节作用增强.④ 生态工程实施后,生物栖息地的生境退化状况轻微改善,野生动物的分布范围和种群数量都有了较为明显的增加.      

电解海水对模拟船舶柴油机废气的脱硝应用

采用无隔膜电解方法对海水进行电解,研究了电极间距、电解时间、电流密度等不同电解条件对电解海水中ρ（有效氯）的影响,并基于模拟船舶柴油机废气实验台以及自行搭建的喷淋反应系统,初步研究了电解海水的脱硝效果.结果表明:随电极间距由5 mm增至25 mm,电解电压逐渐增加,而电解溶液的pH变化不明显;随着电流密度与电解时间的增加,电解溶液中ρ（有效氯）近似呈线性增加.在电解电流密度为100 mA/cm2、电解时间为30 min时,电解溶液中ρ（有效氯）达到2 288 mg/L.当采用非循环喷淋模式进行脱硝试验时,随着电解海水中ρ（有效氯）的增加,NO去除率迅速提高,在ρ（有效氯）为872 mg/L时,NO去除率达到79%.电解海水溶液的初始pH对脱硝效果影响较大,当pH为6.0~8.0时,NO_x去除率高于40%.当采用循环喷淋模式进行脱硝试验时,随着电解海水中ρ（有效氯）的增加,NO去除率及其持续时间均明显改善,当ρ（有效氯）为2 288 mg/L时,电解海水的NO去除率高于80%,并且循环喷淋持续时间大于50 min.研究显示,电解海水溶液具有良好的脱硝效果,在船舶柴油机废气脱硝方面具有重要的应用潜力和研究价值.