Air pollution characteristics and their relationship with emissions and meteorology in the Yangtze River Delta region during 2014–2016

With rapid economic growth and urbanization, the Yangtze River Delta(YRD) region in China has experienced serious air pollution challenges. In this study, we analyzed the air pollution characteristics and their relationship with emissions and meteorology in the YRD region during 2014–2016. In recent years, the concentrations of all air pollutants, except O_3,decreased. Spatially, the PM_(2.5), PM_(10), SO_2, and CO concentrations were higher in the northern YRD region, and NO_2 and O_3 were higher in the central YRD region. Based on the number of non-attainment days(i.e., days with air quality index greater than 100), PM_(2.5) was the largest contributor to air pollution in the YRD region, followed by O_3, PM_(10), and NO_2.However, particulate matter pollution has declined gradually, while O_3 pollution worsened.Meteorological conditions mainly influenced day-to-day variations in pollutant concentrations. PM_(2.5) concentration was inversely related to wind speed, while O_3 concentration was positively correlated with temperature and negatively correlated with relative humidity.The air quality improvement in recent years was mainly attributed to emission reductions.During 2014–2016, PM_(2.5), PM_(10), SO_2, NO_x, CO, NH_3, and volatile organic compound(VOC)emissions in the YRD region were reduced by 26.3%, 29.2%, 32.4%, 8.1%, 15.9%, 4.5%, and0.3%, respectively. Regional transport also contributed to the air pollution. During regional haze periods, pollutants from North China and East China aggravated the pollution in the YRD region. Our findings suggest that emission reduction and regional joint prevention and control helped to improve the air quality in the YRD region.     

Facile synthesis of Ag-modified manganese oxide for effective catalytic ozone decomposition

O₃ decomposition catalysts with excellent performance still need to be developed. In this study, Ag-modified manganese oxides (AgMnO_x) were synthesized by a simple co-precipitation method. The effect of calcination temperature on the activity of MnO_x and AgMnO_x catalysts was investigated. The effect of the amount of Ag addition on the activity and structure of the catalysts was further studied by activity testing and characterization by a variety of techniques. The activity of 8%AgMnO_x for ozone decomposition was significantly enhanced due to the formation of the Ag_1.8Mn₈O₁₆ structure, indicating that this phase has excellent performance for ozone decomposition. The weight content of Ag_1.8Mn₈O₁₆ in the 8%AgMnO_x catalyst was only about 33.76%, which further indicates the excellent performance of the Ag_1.8Mn₈O₁₆ phase for ozone decomposition. The H₂ temperature programmed reduction (H₂-TPR) results indicated that the reducibility of the catalysts increased due to the formation of the Ag_1.8Mn₈O₁₆ structure. This study provides guidance for a follow-up study on Ag-modified manganese oxide catalysts for ozone decomposition.     

One-step synthesis of Cu(II) metal–organic gel as recyclable material for rapid, efficient and size selective cationic dyes adsorption

Efficient removal of non-biodegradable and hazardous dyes from wastewater remains a hot research topic. Herein, a rationally designed a Cu(Ⅱ)-based metal–organic gel(Cu-MOG) with a nanoporous 3 D network structure prepared via a simple one-step mixing method was successfully employed for the removal of cationic dyes. The Cu-MOG exhibited high efficiency, with an adsorption capacity of up to 650.32 mg/g, and rapid adsorption efficiency, with the ability to adsorb 80% of Neutral Red within 1 min. The high adsorption efficiency was attributed to its large specific surface area, which enabled it to massively bind cationic dyes through electrostatic interaction, and a nanoporous structure that promoted intra-pore diffusion. Remarkably, the Cu-MOG displayed size-selective adsorption, based on adsorption studies concerning dyes of different sizes as calculated by density functional theory. Additionally, the adsorption performance of the Cu-MOG still maintained removal efficiency of 100% after three regeneration cycles. These results suggested that the Cu-MOG could be expected to be a promising and competitive candidate to conveniently process wastewater.     

热障涂层对DD6单晶高温合金高周疲劳性能的影响

目的研究电子束物理气相沉积热障涂层对单晶高温合金高周疲劳性能的影响,为热障涂层在涡轮叶片上的应用提供技术支持。方法采用真空电弧镀和电子束物理气相沉积工艺制备YSZ热障涂层,进行900℃条件下高周疲劳性能测试,采用扫描电镜对测试后的试样表面、断口形貌进行观察与分析。结果在900℃、380 MPa条件下,带涂层的DD6单晶试棒循环次数(Nf)超过了107,420 MPa条件下超过了106。通过对DD6单晶试棒断口分析,失效后的带涂层试棒仍以DD6单晶常见滑移解离形式发生破坏。结论高周疲劳性能测试条件下,带YSZ热障涂层的试棒中粘结层率先产生垂直微裂纹,但是裂纹扩展延伸中发生氧化钝化,之后DD6基体沿正常的滑移方向从表面向内部疲劳扩展,带涂层的试棒疲劳裂纹并非由涂层微裂纹直接扩展形成,热障涂层对DD6单晶高温合金高周疲劳性能影响较小。     

ACP1000除气塔液体冷却器抗震分析设计

目的对除气塔液体冷却器进行抗震分析,以确保其在地震下必要的安全功能。方法以福清5/6号核电工程为背景,通过有限元软件ANSYS建立除气塔液体冷却器有限元模型,采用反应谱法进行设备的抗震分析与评定。结果通过抗震分析评定,发现设备鞍座为设计薄弱区域,故修改鞍座的结构形式,包括新增筋板、增加壁厚,使该设备的设计满足了相关规范的要求。结论通过修改鞍座的结构形式,确保其必要的安全功能得以实现,满足实际工程的需要。     

山东省O3时空分布及影响因素分析

为认识山东省环境空气中O3的污染现状,基于2015～2019年国省控环境空气自动监测站的O3监测数据、2019～2020年4～9月气象代表站的气象数据及邻近环境空气站的O3监测数据,探究了山东省O3时空分布特征及与气象因素的关系.结果表明,山东省O3污染日益突出,年均ρ(O3-8h)(90百分位)和ρ(Ox)(O3 与NO2之和)升高速率分别为7.6μg·(m3·a)-1和7.0μg·(m3·a)-1,年均ρ(PM2.5)、ρ(CO)(95百分位数)和ρ(NO2)均逐步下降,下降速率均小于ρ(O3)上升速率.03污染呈现夏季高冬季低的"M型"或"倒V型"月变化特征,在6月或9月达到峰值,且污染月呈提前出现趋势.山东省年均ρ(O3-8h)(90百分位)呈现"内陆高,沿海低"的特点,并有区域均匀性发展趋势.相关性分析表明,山东省ρ(O3-8h)总体与日最高温度呈正相关,与相对湿度、气压和风速呈负相关,其中日 最高温度和相对湿度是O3-8h主控气象因子,气象因素对不同城市O3-8h超标率的影响具有显著差异.     

名山大川的形成(二)

地壳中的岩层受到力的作用发生变形，发生弯曲(褶皱)，无论是向上褶皱，还是向下褶皱，甚至是侧向褶皱，在这种格局下形成的山体，称之为“褶皱山”。显然，这个过程与其他断层作用情况是不一样的。     

制革废水脱硫试验研究

制革废水中含有大量的硫化物，试验研究了催化曝气，混凝沉淀，混凝气浮及生化法等工艺的脱硫效果，并考察了工艺的综合作用。结果表明上述工艺均可全部或近于全部除去废水中的硫化物，并对ＣＯＤ、总Ｃｒ等也有综合的去除功能。     

福美胂在苹果树上的残留

调查了两个果园１５～２０年树龄的苹果树在连续用福美胂喷涂７～１０年后树根、树皮、枝条、叶片、果实和土壤的砷含量，并和未使用福美胂的果树含量做了比较。结果表明，果实中有砷积累，但未超过食品卫生标准。使用福美胂的树皮、技条、叶片中砷含量比未使用福美胂的高儿倍～十几倍，树皮和短梢叶含量最高。枝条和叶片与树皮的砷含量有密切正相关。土壤表层虽有轻度积累，但不会对土壤生态环境有太大影响。