Regeneration of commercial selective catalyst reduction catalysts deactivated by Pb and other inorganic elements

The regeneration of commercial SCR(Selective Catalyst Reduction) catalysts deactivated by Pb and other elements was studied.The deactivated catalyst samples were prepared by chemical impregnation with mixed solution containing K_2SO_4,Na_2SO_4,CaSO_4,Pb(NO_3)_2and NH_4H_2PO_4.A novel method combining Ethylenediaminetetraacetic acid disodium salt(EDTA-2Na) and H_2SO_4solution(viz.catalysts treated by dilute EDTA-2Na and H_2SO_4 solution in sequence) was used to recover the activity of deactivated samples,and the effect was compared with single H_2SO_4,oxalic acid,acetic acid,EDTA or HNO_3 solutions.The surface structure,acidity and reducibility of samples were characterized by N_2adsorption–desorption,inductively coupled plasma optical emission spectrometer(ICP-OES),scanning electron microscopy(SEM),X-ray diffraction(XRD),X-ray fluorescence(XRF),H-2-temperature programmed section(H_2-TPR),NH3-temperature programmed desorption(NH3-TPD) and in situ DRIFTS.Impurities caused a decrease of specific surface area and surface reducibility,as well as Br?nsted acid sites,and therefore led to severe deactivation of the SCR catalyst.The use of an acid solution alone possibly eliminated the impurities on the deactivated catalyst to some extent,and also increased the specific surface area and Br?nsted acid sites and promoted the surface reducibility,thus recovered the activity partially.The combination of EDTA-2Na and H_2SO_4 could remove most of the impurities and improve the activity significantly.The removal of Pb should be an important factor for regeneration.Due to a high removal rate for Pb and other impurities,the combination of EDTA-2Na and H_2SO_4 solutions provided the best efficiency.     

Estimating emissions from crop residue open burning in China based on statistics and MODIS fire products

With the objective of reducing the large uncertainties in the estimations of emissions from crop residue open burning, an improved method for establishing emission inventories of crop residue open burning at a high spatial resolution of 0.25°× 0.25° and a temporal resolution of1 month was established based on the moderate resolution imaging spectroradiometer(MODIS) Thermal Anomalies/Fire Daily Level3 Global Product(MOD/MYD14A1). Agriculture mechanization ratios and regional crop-specific grain-to-straw ratios were introduced to improve the accuracy of related activity data. Locally observed emission factors were used to calculate the primary pollutant emissions. MODIS satellite data were modified by combining them with county-level agricultural statistical data, which reduced the influence of missing fire counts caused by their small size and cloud cover. The annual emissions of CO_2, CO, CH_4,nonmethane volatile organic compounds(NMVOCs), N_2O, NO_x, NH_3, SO_2, fine particles(PM2.5),organic carbon(OC), and black carbon(BC) were 150.40, 6.70, 0.51, 0.88, 0.01, 0.13, 0.07, 0.43,1.09, 0.34, and 0.06 Tg, respectively, in 2012. Crop residue open burning emissions displayed typical seasonal and spatial variation. The highest emission regions were the Yellow-Huai River and Yangtse-Huai River areas, and the monthly emissions were highest in June(37%).Uncertainties in the emission estimates, measured as 95% confidence intervals, range from a low of within ±126% for N_2O to a high of within ± 169% for NH_3.     

中国硫酸盐气溶胶直接辐射效应数值模拟

硫酸盐气溶胶对地球系统能量收支平衡和全球气候变化有重要影响.本研究基于中国2007年二氧化硫排放清单,应用Can METOP、OPAC和SBDART模型,对中国硫酸盐气溶胶直接辐射效应及其空间分布和时间变化进行分析.结果表明,2007年中国硫酸盐气溶胶直接辐射效应全年波动范围在-9.1~0.0008 W·m~(-2)之间,全国年均值为-1.372 W·m~(-2),低于全球均值(-0.35 W·m~(-2)),其中华东地区最强为-5.017 W·m~(-2),西北地区最弱仅为-0.22 W·m~(-2),该空间分布主要受SO_2排放的空间差异及西风导致的向东溢出效应影响.同时,除华南之外的绝大多数地区夏季辐射效应最强、冬季最弱,这主要由SO_2向硫酸盐的转化率及相对湿度的季节差异决定.本研究有助于了解中国硫酸盐气溶胶及其气候效应的时空差异,对评估硫酸盐气溶胶的气候效应有重要意义.     

Prevalence of Rotaviruses Groups A and C in Egyptian Children and Aquatic Environment

The objective of this study is to compare the prevalence of rotaviruses groups A and C in Egyptian children and aquatic environment. From 110 stool specimens of children with acute diarrhea and using RT-PCR, 35 samples (31.8 %) were positive for human rotavirus group A and 15 samples (13.6 %) were positive for human rotavirus group C. From 96 samples collected from Zenin wastewater treatment plant over a 2-year period (November 2009–October 2011) and using RT-PCR, rotavirus group A was detected in (4/24) 16.7 %, (5/24) 20.8 %, (4/24) 16.7 %, and (4/24) 16.7 %, while rotavirus group C was detected in (2/24) 8.3 %, (3/24) 12.5 %, (3/24) 12.5 %, and (0/24) 0 % in raw sewage, after primary sedimentation, after secondary sedimentation, and after final chlorination, respectively. Moreover, from 96 samples collected from El-Giza water treatment plant over a 2-year period (November 2009–October 2011), rotavirus group A was detected in (7/24) 29.2 %, (6/24) 25 %, (5/24) 20.8 %, and (3/24) 12.5 %, while rotavirus group C was detected in (3/24) 12.5 %, (1/24) 4.2 %, (1/24) 4.2 %, and (0/24) 0 % in raw Nile water, after sedimentation, after sand filtration, and after final chlorination, respectively. Using SYBR Green real-time RT-PCR, the number of human rotavirus group A genome or infectious units was higher than rotavirus group C. VP6 sequence analysis of the RT-PCR positive rotavirus group C samples revealed that four clinical specimens and three environmental samples showed similar sequences clustered with Moduganari/Human Nigerian strain AF 325806 with 98 % homology, and two clinical specimens and one environmental sample showed similar sequences clustered with Dhaka CB/Human Bangladesh strain AY 754826 with 97 % homology.     

基于TM影像的城市地表湿度对城市热岛效应的调控机理研究

论文以探究城市热岛效应调控机理为研究目的,以徐州地区1985-2010 年夏季四期Landsat TM影像为研究数据,应用单窗算法、K-T变换、空间叠加分析以及缓冲区分析等研究方法,对徐州市城市热岛时空变化特征进行了反演,重点对徐州市城市热岛强度的调控机理进行了分析并提出了通过K-T变换提取表示城市建成区内部植被与水体覆盖程度的城市地表湿度(ULSW)这一新指标.研究结果显示:城市地表湿度显著区对城市热岛效应起到了有效的调控作用,并且随着城市地表湿度值的提高,区域内部以及周围环境的温度都会随之下降.城市地表湿度指标对于城市热岛效应的调控水平具有一定的代表意义.     

宁蒙沿黄地带城镇用地扩展驱动力分析与情景模拟

宁蒙沿黄地带属于中国西北干旱半干旱快速城市化地区,研究这一典型地区的城镇用地扩展对丰富城镇用地扩展机制的理论研究和提供相应政策建议具有理论和现实意义。论文利用Logistic回归分析2000-2005年城镇用地扩展的主要驱动力,计算城镇用地转换适宜度矩阵,结合CA-Markov模型模拟3种情景下城镇用地扩展趋势。结果表明：2000-2005年,城镇用地的主要来源是耕地,其次是草地及极少量农村居民点和工矿用地。对城镇用地变化影响最大的因素依次是邻域内城镇用地比重、年降水量、到2001年国道距离、到水域距离、到2001年省道距离以及到2000年土地利用中耕地、林地和草地的距离。一切照常情景下,2016年宁蒙沿黄地带城镇用地总量约997 km²,主要分布在呼和浩特市区、包头市区等主要城市边缘;规划情景下,城镇用地规模达到1 525 km²,分布格局与一切照常情景类似;生态保护情景下,城镇用地规模总量达到1 480 km²,城镇用地沿交通轴扩展呈组团分布。由此得出主要结论：大城市边缘区和交通线是城镇用地发生的主要影响因素;通过总量控制的区域整体城镇用地规划可以优化区域整体城镇用地扩展格局。     

废气量减排对大气污染控制技术效率的要求

雾霾问题已经成为我国目前面临的主要大气环境污染问题,废气量减排是消除我国雾霾污染的有效途径之一。综述了国内外烟气量减排的现状,在此基础上分析了废气量减排对污染物排放浓度的影响。结果表明,废气量减排技术的应用对大气污染控制技术提出了更高的要求,需将除尘效率提高到99.95%,脱硫效率提高到97.5%,脱硝效率提高到75%。     

城乡空置住房的识别、特征与成因——基于华北平原X县用电量等多源数据

对空置住房进行精准感知在国土空间规划中具有重要意义。基于华北X县2019年全县居民用电大数据构建了一种精准的空置识别和空置率计算模型。结果显示：该县出现过空置的住房占比高达33.81%,年空置率为21.64%;月空置率在一年中随月份小幅规律波动,波谷出现在2月和8月,波峰出现在5月和11月;村空置率具有空间自相关属性,县城为空置率高值集聚区;全年性空置为1931种空置节律模式中最主要的一种。将空置成因归纳为举家迁移和入城团聚等新流动模式促使全年空置和春节空置增多;扩展家庭内部住房过滤引发老旧住房空置;县城住房城镇化导致中心城区出现空置。应重视空置识别在国土空间规划中的基础作用,客观看待乡村住房空置现象,高度警惕县城的高空置率问题。     

基于秸秆后发酵产沼气的一次发酵时间优化

采用"一次发酵+NaOH处理+二次发酵"工艺,以稻秸为原料,研究一次发酵时间对稻秸沼气发酵的影响.结果表明,一次发酵后的稻秸仍有一定的产气能力,干物质(TS)产气量为28.11～50.73mL/g TS,产气量大小与一次发酵时间成反比;一次发酵后的稻秸经NaOH处理后,稻秸物质结构受到明显破坏,有机物大量溶出,稻秸浸提...