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881.
Ten years of atmospheric methane observations at a high elevation site in Western China 总被引:3,自引:0,他引:3
L.X. Zhou D.E.J. Worthy P.M. Lang M.K. Ernst X.C. Zhang Y.P. Wen J.L. Li 《Atmospheric environment (Oxford, England : 1994)》2004,38(40):7041-7054
In this paper, the continuous (1994–2001) and discrete air sample (1991–2001) measurements of atmospheric CH4 from the Waliguan Baseline Observatory located in western China (36°17′N, 100°54′E, 3816 m asl) are presented and characterized. The CH4 time series show large episodic events on the order of 100 ppb throughout the year. During spring, a diurnal cycle with average amplitude of 7 ppb and a morning maximum and late afternoon minimum is observed. In winter, a diurnal cycle with average amplitude of 14 ppb is observed with an afternoon maximum and morning minimum. Unlike most terrestrial observational sites, no obvious diurnal patterns are present during the summer or autumn. A background data selection procedure was developed based on local horizontal and vertical winds. A selected hourly data set representative of “baseline” conditions was derived with approximately 50% of the valid hourly data. The range of CH4 mixing ratios, annual means, annual increases and mean annual cycle at Waliguan during the 1992–2001 were derived from discrete and continuous data representative of “baseline” conditions and compared to air samples collected at other Northern Hemisphere sites. The range of CH4 monthly means of 1746–1822 ppb, average annual means of 1786.7±10.8 ppb and mean annual increase of 4.5±4.2 ppb yr−1 at Waliguan were inline with measurements from sites located between 30° and 60°N. There were variations observed in the CH4 annual increase patterns at Waliguan that were slightly different from the global pattern. The mean CH4 annual cycle at Waliguan shows an unusual pattern of two gentle peaks in summer and February along with two small valleys in early winter and spring and a mean peak-to-peak amplitude of 11 ppb, much smaller than amplitudes observed at most other mid- and high-northern latitude sites. The Waliguan CH4 data are strongly influenced by continental Asian CH4 emissions and provide key information for global atmospheric CH4 models. 相似文献
882.
Source diagnostics of polycyclic aromatic hydrocarbons in urban road runoff, dust, rain and canopy throughfall 总被引:6,自引:0,他引:6
Zhang W Zhang S Wan C Yue D Ye Y Wang X 《Environmental pollution (Barking, Essex : 1987)》2008,153(3):594-601
Diagnostic ratios and multivariate analysis were utilized to apportion polycyclic aromatic hydrocarbon (PAH) sources for road runoff, road dust, rain and canopy throughfall based on samples collected in an urban area of Beijing, China. Three sampling sites representing vehicle lane, bicycle lane and branch road were selected. For road runoff and road dust, vehicular emission and coal combustion were identified as major sources, and the source contributions varied among the sampling sites. For rain, three principal components were apportioned representing coal/oil combustion (54%), vehicular emission (34%) and coking (12%). For canopy throughfall, vehicular emission (56%), coal combustion (30%) and oil combustion (14%) were identified as major sources. Overall, the PAH's source for road runoff mainly reflected that for road dust. Despite site-specific sources, the findings at the study area provided a general picture of PAHs sources for the road runoff system in urban area of Beijing. 相似文献
883.
Guoyang Fan Zhenying Zhang Jiahe Zhang Jiayue Zhang Qiaona Wang Min Wang Bang Wang Chengyu Nie 《Frontiers of Environmental Science & Engineering》2022,16(12):160
884.
大气中多环芳烃的来源及采样方式的研究 总被引:12,自引:0,他引:12
本文对大气中多环芳烃的来源进行了调查的基础上,对燃源,交通源,等采产方式进行了综述,评价了各种采样方式的优缺点,从而造反我环芳烃污染源解析的采样方式。 相似文献
885.
Ce含量对Pd/Al2O3催化剂加氢脱硫性能的影响 总被引:1,自引:0,他引:1
采用浸渍法制备了Pd/Al2O3和Pd-CeO2/Al2O3催化剂,研究了不同Ce含量对Pd/Al2O催化剂加氢脱硫性能的影响,并运用XRD、TPR、TPD和噻吩吸附等手段表征了催化剂的吸附性能和酸性。结果表明,CeO2的加入导致Pd/Al2O3催化剂H2吸附性能的减弱和酸量的减少,但提高了噻吩的吸附性能。在噻吩加氢脱硫反应中,Ce含量为2%时Pd-CeO2/Al2O3催化剂的活性最高,随Ce含量的继续增加催化剂的活性下降,是由于催化剂对H2吸附和噻吩吸附综合影响的结果。 相似文献
886.
非平衡等离子体联合技术降解甲苯气体 总被引:7,自引:1,他引:6
采用了自制的纳米钛酸钡基介电材料作为催化剂,以电工陶瓷拉西环作为载体,利用介质阻挡放电产生的非平衡态等离子体对常压下流动态含甲苯的空气进行处理,研究了电场强度、流速、初始浓度及不同填料情况下甲苯的降解及臭氧产生情况,初步探讨了等离子体催化降解甲苯的机理,并进行了产物分析.实验结果表明,电场强度小于13kV·cm-1时,甲苯降解率和臭氧产生浓度随电场强度的提高而上升,随气速和初始浓度的增加而降低;不同填料下降解率及臭氧浓度由大到小排序为有催化剂填料、普通填料、无填料,有催化剂存在时(电场强度为14kV·cm-1,流速为0.3 m3·h-1,甲苯浓度为600 mg·L-1),甲苯降解率最高可达95%.当电场强度>13kV·cm-1时,臭氧浓度因受到过量的高能电子攻击而发生分解.表现为臭氧浓度随电场强度的继续增加而降低.因此,电场强度为13kV·cm-1时,产生的臭氧浓度最高. 相似文献
887.
污泥渗水砖的制备研究 总被引:2,自引:0,他引:2
结合压制成型和传统的烧结砖工艺,实验以城市生活污泥、黄河淤泥、煤矸石及砂为原料,制备渗水铺地砖。通过正交试验得到最优工艺参数为w(黄河淤泥)∶ww(煤矸石)∶w(污泥)∶w(砂)=33%∶22%∶15%∶30%、成型压力为20 MPa、烧结温度为1 100℃、保温时间为1.5 h,骨料砂的粒径为1~2 mm。制备的成品抗压强度为21.8 MPa,渗水系数为1.03×10-2 cm/s。并对成型压力及烧结温度对渗水砖抗压强度及渗水系数的影响进行了讨论。 相似文献
888.
889.
大气颗粒物源解析受体模型应用研究及发展现状 总被引:8,自引:2,他引:6
通过大量文献资料调研对化学质量平衡模型、二重源解析技术、主因子分析、正矩阵因子分析法等目前应用较广泛的受体模型方法的原理、优缺点和应用现状进行了比较分析,对单颗粒源解析方法、有机物示踪技术和扩散与受体模型联用技术等受体模型新技术方法进行了评述。 相似文献
890.