午夜欧美大片免费观看,欧美激情综合五月色丁香,亚洲日本在线视频观看,午夜精品福利在线

The samples were obtained from two observation stations for nonmethane hydrocarbons (NMHCs): Beijing University of Technology (urban site) and Xinan, Baodi of Tianjin (rural site) from 6 April to 20 May in 2006. A total of 80 samples were obtained during two periods, with 55 compounds were detected, including 25 Alkanes, 19 Alkenes and 10 aromatics. It can be seen from the components and concentrations of NMHCs in both urban and rural atmosphere that the average concentrations of TNMHCs are 438.1±1731 μg/m3and 1938±1844 μg/m3, respectively. The urban level is 23 times as high as that of the rural one , and the lowest value of TNMHCs in rural atmosphere is only one fifth of that in the urban atmosphere.