基于车载差分吸收光谱技术的唐山SO_(2)和NO_(x)污染分布及排放研究

Study of SO_(2) and NO_(x) Distribution and Emission in Tangshan Based on Mobile DOAS Techniques

二氧化硫(SO_(2))和氮氧化物(NO_(x))作为大气中重要的一次排放物,人为活动造成SO_(2), NO_(x)的过度排放会对生态环境和人体健康产生巨大危害,2018年环境保护部就规定了“2+26”城市需要执行大气污染物的特别排放限值,如:燃煤锅炉排放限值规定的二氧化硫、氮氧化物均为200μg·m-3,因此了解这些城市中SO_(2)和NO_(x)的分布与排放对大气污染防控管制具有重要意义。唐山市作为“2+26”城市中大气污染最为严重的重工业城市之一,近年来实施了多项大气污染防治措施,但空气质量问题仍然严峻。2021年2月26至3月1日,使用基于车载差分吸收光谱技术的移动污染气体监测系统对于唐山市区开展了走航观测实验,获取了走航路径上NO_(x)和SO_(2)的空间立体分布以及走航区域的排放通量。实验结果表明唐山市一环存在多处NO_(2)高值区域,均位于车辆较为集中的立交和路口处。工业园的走航中部分企业存在高NO_(2)、 SO_(2)的排放,且获取的NO_(2)和SO_(2)VCD均值较高,分别是一环的1.75~1.99倍和2.21~3.44倍。结合垂直柱浓度SO_(2)/NO_(2)的比值以及近地面浓度CO/NO_(2)的比值,并用Pearson相关系数确定SO_(2)和NO_(2)柱浓度以及NO_(2)近地面浓度和柱浓度之间的相关性,进一步分析不同区域的主要污染源,结果表明,一环走航获取的SO_(2)/NO_(2)最低为0.42,CO/NO_(2)最高为10.88, NO_(2)地表与柱浓度之间的相关性r达到0.56, 3月1日丰南工业园区走航中,获取的SO_(2)/NO_(2)最高为0.81, CO/NO_(2)最低为7.13, SO_(2)与NO_(2)VCD之间有良好的相关性r为0.787,唐山市一环区域大气污染物以车辆交通尾气排放为主,丰南工业园区大气污染物来源以工业生产过程中高架点源(烟囱)释放的大量NO_(2)和SO_(2)为主。

Sulfur dioxide(SO_(2))and nitrogen oxides(NO_(x))as important primary emissions in the atmosphere.Anthropogenic activities of SO_(2) and NO_(x) excessive emissions will cause great harm to the ecological environment and human health,in 2018 the Ministry of Environmental Protection“Announcement on the implementation of special emission limits for air pollutants in cities in the Beijing-Tianjin-Hebei air pollution transmission corridor”on the“2+26”cities need to implement special emission limits for SO_(2),NO_(x) and other air pollutants,so it is important to understand the distribution and emission of SO_(2) and NO_(x) in these cities for air pollution prevention and control.As one of the heavy industrial cities with the most serious air pollution among the“2+26”cities,Tangshan City has implemented many air pollution prevention and control measures in recent years,but the air quality is still not optimistic.Therefore,in order to obtain the time and space distribution of the main pollutants in the urban area of Tangshan City,to quantitatively analyze the emissions of different regional sources,and to identify the sources of the main pollutants,a mobile pollution gas monitoring system based on mobile DOAS techniques was used from February 26 to March 1,2021,to conduct aerial observation experiments for the urban area of Tangshan City and some industrial parks(steel,thermoelectric and coking enterprises)to obtain the Spatial distribution of NO_(x) and SO_(2) along its course and the emission fluxes in the moving area.The experimental results show several areas with high NO_(2) values in the first ring of Tangshan City,all of which are located at interchanges and junctions where vehicles are concentrated.The NO_(2) and SO_(2)VCD obtained in the walkway of the industrial park are both higher,1.75~1.99 times and 2.21~3.44 times higher than those of the first ring,respectively,and there are high NO_(2) and SO_(2) emissions from some enterprises in the industrial park.Combining the ratio of vertical column concentration SO_(2)/NO_(2) and the ratio of near-ground concentration CO/NO_(2) and using the Pearson correlation coefficient to determine the correlation between SO_(2) and NO_(2) column concentration and NO_(2) near-ground concentration and column concentration,further analyzing the main pollution sources in different areas,the results show that the lowest SO_(2)/NO_(2) obtained by the first ring walkway is 0.42,CO/NO_(2).The highest correlation r between NO_(2) surface and column concentrations reached 0.56.The highest SO_(2)/NO_(2) and lowest CO/NO_(2) was 0.81 and 7.13 in the March 1 aerial walk in Fengnan Industrial Park,with a good correlation r between SO_(2) and NO_(2)VCD of 0.787.The air pollutants in the first ring area of Tangshan City are mainly vehicular traffic exhaust emissions.The sources of air pollutants in the Fengnan Industrial Park are dominated by a large amount of NO_(2) and SO_(2) released from elevated point sources(chimneys)during industrial production.