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791.
Heon-Sook Kim Yuichi Nagata Kenji Kai 《Atmospheric environment (Oxford, England : 1994)》2009,43(3):557-567
LIDAR observations were conducted in the northern Taklimakan Desert to investigate the vertical distribution of dust in April 2002. During the observation period, a dust outbreak occurred on 13 April, remaining over the desert for several days. Despite only slight variations being observed in dust layer height before the dust event, marked diurnal variation in dust layer height was observed after the dust event. In this study, we conducted two numerical simulations to investigate differences in the variation exhibited by the dust layer heights before and after the dust event, and assessed the influence of meteorological conditions on this variation. The simulated results show that the clearly diurnal variation in dust layer height is strongly influenced by local circulation which is affected by the characteristic topography and synoptic conditions of the Tarim Basin. 相似文献
792.
793.
In this work, we investigate the frequency-size distribution of three pollution indexes (PM10, NO2 and SO2) in Shanghai. They are well approximated by power-law distributions, which suggest that air pollution might be a manifestation of self-organized criticality. We introduce a new numerical sandpile model with decay coefficient to reveal inherent dynamic mechanism of air pollution. Only changing the number value of decay coefficient of pollutants, this model gives a good simulation of three pollutants' statistical characteristic. This work shows that it is the self-organized criticality of the air pollutants that results in the temporal variation of air pollutant indexes and the minor air pollution sources can trigger the occurrence of large pollutant events by SOC behavior. 相似文献
794.
Litao Wang Carey Jang Yang Zhang Kai Wang Qiang Zhang David Streets Joshua Fu Yu Lei Jeremy Schreifels Kebin He Jiming Hao Yun-Fat Lam Jerry Lin Nicholas Meskhidze Scott Voorhees Dale Evarts Sharon Phillips 《Atmospheric environment (Oxford, England : 1994)》2010,44(28):3442-3448
Under the 11th Five Year Plan (FYP, 2006–2010) for national environmental protection by the Chinese government, the overarching goal for sulfur dioxide (SO2) controls is to achieve a total national emissions level of SO2 in 2010 10% lower than the level in 2005. A similar nitrogen oxides (NOx) emissions control plan is currently under development and could be enforced during the 12th FYP (2011–2015). In this study, the U.S. Environmental Protection Agency (U.S.EPA)’s Community Multi-Scale Air Quality (Models-3/CMAQ) modeling system was applied to assess the air quality improvement that would result from the targeted SO2 and NOx emission controls in China. Four emission scenarios — the base year 2005, the 2010 Business-As-Usual (BAU) scenario, the 2010 SO2 control scenario, and the 2010 NOx control scenario—were constructed and simulated to assess the air quality change from the national control plan. The Fifth-Generation NCAR/Penn State Mesoscale Model (MM5) was applied to generate the meteorological fields for the CMAQ simulations. In this Part I paper, the model performance for the simulated meteorology was evaluated against observations for the base case in terms of temperature, wind speed, wind direction, and precipitation. It is shown that MM5 model gives an overall good performance for these meteorological variables. The generated meteorological fields are acceptable for using in the CMAQ modeling. 相似文献
795.
Peter Harborth Roland Fuß Kai Münnich Heinz Flessa Klaus Fricke 《Waste management (New York, N.Y.)》2013,33(10):2099-2107
Mechanical biological treatment (MBT) is an effective technique, which removes organic carbon from municipal solid waste (MSW) prior to deposition. Thereby, methane (CH4) production in the landfill is strongly mitigated. However, direct measurements of greenhouse gas emissions from full-scale MBT landfills have not been conducted so far. Thus, CH4 and nitrous oxide (N2O) emissions from a German MBT landfill in operation as well as their concentrations in the landfill gas (LFG) were measured. High N2O emissions of 20–200 g CO2 eq. m?2 h?1 magnitude (up to 428 mg N m?2 h?1) were observed within 20 m of the working face. CH4 emissions were highest at the landfill zone located at a distance of 30–40 m from the working face, where they reached about 10 g CO2 eq. m?2 h?1. The MBT material in this area has been deposited several weeks earlier. Maximum LFG concentration for N2O was 24.000 ppmv in material below the emission hotspot. At a depth of 50 cm from the landfill surface a strong negative correlation between N2O and CH4 concentrations was observed. From this and from the distribution pattern of extractable ammonium, nitrite, and nitrate it has been concluded that strong N2O production is associated with nitrification activity and the occurrence of nitrite and nitrate, which is initiated by oxygen input during waste deposition. Therefore, CH4 mitigation measures, which often employ aeration, could result in a net increase of GHG emissions due to increased N2O emissions, especially at MBT landfills. 相似文献
796.
研究了不同时空条件下噬藻体的分布与效力的变化.2001年8~11月共采集了18个水样,对14种藻进行直接感染,从其中的5个水样中分离到了噬藻体(蓝藻病毒),它们主要来源于降温以前富营养化池塘的水样,同时分离得到了4株溶藻细菌.在接受直接感染的14种藻中,聚球藻、组囊藻、微囊藻、织线藻、鱼腥藻7120、衣藻及小球藻为敏感种类,而螺旋藻、念珠藻、鞘丝藻、颤藻、鱼腥藻595、鱼腥藻1444、栅藻则为不敏感种类,敏感种类中织线藻受到噬藻体的感染,聚球藻、微囊藻和织线藻受到溶藻细菌的溶解.从富营养化的池塘采集的水样溶藻能力最强,其次为清水(自来水源)池塘,而大中型湖泊与河流水样的溶藻效果最差.随着温度的降低,水样的感染能力下降. 相似文献
797.
复合纳米Fe2O3/TiO2可见光催化降解邻甲酚溶液的研究 总被引:5,自引:2,他引:3
以复合纳米Fe2O3/TiO2作为催化剂,日光色镝灯为光源,研究了邻甲酚溶液的可见光降解。考察了催化剂制备方法、催化剂使用量、溶液pH、催化剂重复使用等条件对可见光降解的影响。实验结果表明,1%Fe2O3/TiO2(n)对邻甲酚溶液的可见光降解效果最优,比Ti02(p25)的降解率提高了2.6倍。在实验条件下,可见光降解3h,邻甲酚溶液的浓度去除率达95.4%,TOC去除率为72.3%。在较宽的浓度范围内,邻甲酚的反应服从一级动力学反应方程,随着浓度的增大,反应速率常数不断降低。 相似文献
798.
799.
为有效引导大学生突发公共事件的舆情演化,分析了大学生突发公共事件舆情发展过程中主、客体及中间介质3个主要影响因素,探讨了大学生舆情传播渠道、传播特性及传播规律,并基于对大学生突发公共事件舆情演化因素和传播特性的研究,详述了舆情形成、增长、稳定、消减直至衰末的发展演化规律,提出了以“理性监督,及时介入,明确导向,主动引导”为基本原理的舆情主动引导模式.该模式根据不同阶段的舆情特点,对其管理提供相应的引导策略,也可用于提升学生分析信息的能力,促使舆情朝积极方向发展,帮助大学生建立正确的价值观.通过对西安某高校应对Norovirus病毒感染事件案例的分析表明,学校相关部门及老师通过舆情主动引导模式,理性监督并快速反应,可在短时间内有效控制负面舆情.通过及时在官方平台发布对事件处理的进展,可减缓负面舆情的传播和发酵速度,实现舆情正向快速发展,进而缩短事态发展的整个周期. 相似文献
800.
Li Liubo Li Yanhui Yang Kai Luan Xinyu Li Meixiu Cui Mingfei Sun Yong Wang Huimin Sun Qinye Tang Kaili Xu Wenshuo Zheng Heng 《Journal of Polymers and the Environment》2021,29(6):1752-1762
Journal of Polymers and the Environment - In this study, novel composite aerogels of peach gum/activated carbon (PGAC) and peach gum/graphene oxide (PGGO) were synthesized by freeze-drying method... 相似文献