地铁多线换乘车站火灾模型实验研究—(1)模型装置设计

为研究地铁网络化运营枢纽车站火灾烟气扩散特征和防排烟技术,根据工程资料和标准规范对典型多线换乘车站进行1∶10火灾实验模型设计,并依据设计方案完成车站模型主体结构和通风排烟系统的搭建,同时在各个防烟分区设计安装温度、流速、烟气浓度和热辐射测量装置,可实现对“T”形、“十”形和“L”形换乘等不同换乘形式车站的火灾场景模拟和危险参数测量。研究结果表明:该模型装置能够开展一系列针对不同换乘形式和通风模式的火灾实验,对于全面揭示大型换乘车站火灾烟气运动规律、验证并优化火灾防排烟设计方法、支撑复杂结构枢纽车站火灾烟气控制技术具有重要意义。     

内窥镜检查在电站锅炉内部检验中的应用

工业内窥镜是电站锅炉内部检验中不可或缺的设备,主要用来对集箱、减温器、受热面管等内部人眼无法观察到的地方进行检验,从而确定承压部件内部是否存在严重影响锅炉安全运行的缺陷.本文通过对锅炉内窥实例进行分析和总结,阐述内窥镜检查在锅炉内检中的重要性并给相关工作人员提供借鉴与参考.     

Enhanced triallyl isocyanurate (TAIC) degradation through application of an O3/UV process: Performance optimization and degradation pathways

• UV/O₃ process had higher TAIC mineralization rate than O₃ process. • Four possible degradation pathways were proposed during TAIC degradation. • pH impacted oxidation processes with pH of 9 achieving maximum efficiency. • CO₃^2– negatively impacted TAIC degradation while HCO₃^– not. • Cl^– can be radicals scavenger only at high concentration (over 500 mg/L Cl^–). Triallyl isocyanurate (TAIC, C₁₂H₁₅N₃O₃) has featured in wastewater treatment as a refractory organic compound due to the significant production capability and negative environmental impact. TAIC degradation was enhanced when an ozone(O₃)/ultraviolet(UV) process was applied compared with the application of an independent O₃ process. Although 99% of TAIC could be degraded in 5 min during both processes, the O₃/UV process had a 70%mineralization rate that was much higher than that of the independent O₃ process (9%) in 30 min. Four possible degradation pathways were proposed based on the organic compounds of intermediate products identified during TAIC degradation through the application of independent O₃ and O₃/UV processes. pH impacted both the direct and indirect oxidation processes. Acidic and alkaline conditions preferred direct and indirect reactions respectively, with a pH of 9 achieving maximum Total Organic Carbon (TOC) removal. Both CO₃^2– and HCO₃^– decreased TOC removal, however only CO₃^2– negatively impacted TAIC degradation. Effects of Cl^– as a radical scavenger became more marked only at high concentrations (over 500 mg/L Cl^–). Particulate and suspended matter could hinder the transmission of ultraviolet light and reduce the production of HO· accordingly.     

Catalytic oxidation of CO over Pt/Fe3O4 catalysts: Tuning O2 activation and CO adsorption

• Strong metal-support interaction exists on Pt/Fe₃O₄ catalysts. • Pt metal particles facilitate the formation of oxygen vacancies on Fe₃O₄. • Fe₃O₄ supports enhance the strength of CO adsorption on Pt metal particles. The self-inhibition behavior due to CO poisoning on Pt metal particles strongly impairs the performance of CO oxidation. It is an effective method to use reducible metal oxides for supporting Pt metal particles to avoid self-inhibition and to improve catalytic performance. In this work, we used in situ reductions of chloroplatinic acid on commercial Fe₃O₄ powder to prepare heterogeneous-structured Pt/Fe₃O₄ catalysts in the solution of ethylene glycol. The heterogeneous Pt/Fe₃O₄ catalysts achieved a better catalytic performance of CO oxidation compared with the Fe₃O₄ powder. The temperatures of 50% and 90% CO conversion were achieved above 260°C and 290°C at Pt/Fe₃O₄, respectively. However, they are accomplished on Fe₃O₄ at temperatures higher than 310°C. XRD, XPS, and H₂-TPR results confirmed that the metallic Pt atoms have a strong synergistic interaction with the Fe₃O₄ supports. TGA results and transient DRIFTS results proved that the Pt metal particles facilitate the release of lattice oxygen and the formation of oxygen vacancies on Fe₃O₄. The combined results of O₂-TPD and DRIFTS indicated that the activation step of oxygen molecules at surface oxygen vacancies could potentially be the rate-determining step of the catalytic CO oxidation at Pt/Fe₃O₄ catalysts. The reaction pathway involves a Pt-assisted Mars-van Krevelen (MvK) mechanism.     

Combined toxicity of imidacloprid,acetochlor, and tebuconazole to zebrafish ( Danio rerio ): acute toxicity and hepatotoxicity assessment

Compound pollution refers to two or more kinds of pollutants with different properties, a pollutant from different sources, or the simultaneous existence of two or more different types of pollutants in the same environment. In this study, we aimed to investigate the individual and combined toxicity of the insecticide imidacloprid (IMI), the herbicide acetochlor (ACT), and the fungicide tebuconazole (TBZ) to zebrafish. The acute toxicity test results showed that the 96-h LC50 values of IMI, ACT, and TBZ were 276.84 (259.62–294.35) mg active ingredient (a.i.) L−1, 1.52 (1.34–1.74) mg a.i. L−1, and 8.16 (7.7–8.6) mg a.i. L−1, respectively. The combinations of IMI, ACT, and TBZ with toxicity ratios of 1:2:2, 1:4:4, 2:4:1, and 4:1:4 displayed synergistic toxic effects on zebrafish, while the toxicity ratios of 1:1:1, 1:1:2, 2:1:2, 2:2:1, and 4:2:1 of IMI, ACT, and TBZ, respectively, exhibited antagonistic toxic effects on zebrafish. The following experiments were performed with a toxicity ratio of 1:4:4 (IMI:ACT:TBZ). The activities of four enzyme biomarkers related to oxidative stress in the liver, catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), and malondialdehyde (MDA) content were evaluated in each exposure group on days 7, 14, 21, and 28. Compared with those of the control group, the activities of CAT, SOD, and GST and the MDA content were significantly altered at different time points in the individual and combined exposure groups. Additionally, the activities of CAT, SOD, and GST and the MDA content were significantly altered in the combined group compared with those of the individual group after 14 days or 21 days of exposure. Therefore, it was confirmed that combined toxicity studies are indispensable in risk assessment.     

Removal of trace Cr(VI) from aqueous solution by porous activated carbon balls supported by nanoscale zero-valent iron composites

Environmental Science and Pollution Research - In this study, porous activated carbon balls supported by nanoscale zero-valent iron composites (Fe@PACB-700) were used for the first time for the...     

Evaluation of Carbon Uptake and Emissions by Forests in Korea During the Last Thirty Years (1973–2002)

The contribution of Korean forests to carbon sequestration for anthropogenic carbon emissions was evaluated. In addition, monitoring of carbon species released from forest fires was conducted. Despite a high carbon uptake by Korean forests, a tremendous increase in fossil fuel burning resulted in a small contribution by forests to carbon removal. The removal efficiency had a 5–31% range with an average of 12% during the period 1973–2002. In 2000, the amount of carbon released from burned trees corresponded to 1.6% of carbon uptake by forests. The distribution of surface CO concentration (ppb) derived from MOPITT (Measurement of Pollution in the Troposphere) showed high CO levels over the East/Japan Sea on April 10, 2000 when the largest forest fires occurred along the east coast of Korea. Trajectory analysis and ground CO measurements also indicated that CO levels over the East/Japan Sea were influenced by forest fires. This study suggests that continuous monitoring of carbon emissions from forest fires is needed for a more reliable estimate of carbon flux in the environment.     

流域绿水管理博弈建模及应用分析

绿水资源表示水循环通过降水渗透入土壤非饱和层并由植物蒸腾或土壤蒸发返回大气层的水汽,是农业作物生产的重要基础,但是通常被传统流域水资源管理所忽视。基于流域水量平衡和蓝水绿水综合思维,将绿水资源纳入流域水资源管理体系。在绿水信贷理念和博弈建模分析框架下,结合SWAT分布式水文模型、多目标优化及情景比较分析,利用绿水管理措施合理优化配置流域蓝水绿水资源,采用绿水生态补偿协调处理上下游利益冲突的博弈问题,探索性地提出了流域绿水管理博弈框架。该框架通过博弈建模可以识别分析流域绿水管理问题的博弈空间、博弈结构和纳什均衡等博弈特征;通过合作博弈约束条件改进的多目标优化,可以计算流域绿水管理情景的绿水补偿标准和帕累托最优收益。将建立的绿水管理博弈框架应用于涟水流域实例研究,NSE、R2、PBIAS、p-factor与r-factor等模拟效果评价和不确定性分析结果表明,涟水流域SWAT分布式水文模型的蓝水绿水模拟均达到可信程度。上下游收益变化、绿水补偿标准与帕累托最优解集等博弈分析结果显示,涟水流域整体社会经济与生态环境收益明显改善,其帕累托最优收益平均增长2.72亿元/a,年均绿水补偿标准折合1.94、1 253.7元/hm²。实例分析表明提出的绿水管理博弈框架在涟水流域具有较好的适用性和可行性。因此,该方法可以为流域蓝水绿水管理试点研究及其绿水补偿标准核定提供相关理论依据和技术参考,具有一定程度的的应用价值和现实意义。     

Effect of Soybean Cultivation on Soil Collembola Community in Marshland of Sanjiang Plain,China

The Sanjiang Plain, the largest inland freshwater marshland in China, was extensive reclaimed into agricultural land. To assess the effects of marshland reclamation on Collembola, we investigated collembolan communities in a chronosequence of soybean plantations (2, 15, and 25 years) in Sanjiang marshland, Northeastern China. We found that: 1) the densities and species richness of Collembola were promoted after short-term (2 years) cultivation of soybean, but significantly decreased after medium-term cultivation (15 years); 2) the densities of epi-edaphic Collembola increased while the densities of hemi-edaphic Collembola decreased as the elongation of soybean cultivation; 3) compared with S0, two species of Collembola appeared while five species disappeared in S25. The changes of plant communities and the soil traits were supposed to be the key factors affecting the composition of soil Collembola. We thus suggest that original marshland should be saved for preserving high diversity and densities of Collembola in the Sanjiang Plain.

     

Chemical speciation,transport and contribution of biomass burning smoke to ambient aerosol in Guangzhou,a mega city of China

Intensive measurements of aerosol (PM₁₀) and associated water-soluble ionic and carbonaceous species were conducted in Guangzhou, a mega city of China, during summer 2006. Elevated levels of most chemical species were observed especially at nighttime during two episodes, characterized by dramatic build-up of the biomass burning tracers levoglucosan and non-sea-salt potassium, when the prevailing wind direction had changed due to two approaching tropical cyclones. High-resolution air mass back trajectories based on the MM5 model revealed that air masses with high concentrations of levoglucosan (43–473 ng m^?3) and non-sea-salt potassium (0.83–3.2 μg m^?3) had passed over rural regions of the Pearl River Delta and Guangdong Province, where agricultural activities and field burning of crop residues are common practices. The relative contributions of biomass burning smoke to organic carbon in PM₁₀ were estimated from levoglucosan data to be on average 7.0 and 14% at daytime and nighttime, respectively, with maxima of 9.7 and 32% during the episodic transport events, indicating that biomass and biofuel burning activities in the rural parts of the Pearl River Delta and neighboring regions could have a significant impact on ambient urban aerosol levels.