Characterization of atmospheric trace gases and particulate matter in Hangzhou, China
Characterization of atmospheric trace gases and particulate matter in Hangzhou, China
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中国杭州大气痕量气体和颗粒物特征
DOI：
10.5194/acp-18-1705-2018
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发表时间：
2018
影响因子：
6.3
通讯作者：
Wanyun Xu
中科院分区：
文献类型：
--
作者：
Gen Zhang;Honghui Xu;Bing Qi;Rongguang Du;Ke Gui;Hongli Wang;Wanting Jiang;Linlin Liang;Wanyun Xu
抽象的。长江三角洲（YRD）是中国人口最稠密的地区之一，其严重的空气质量问题尚未得到充分认识。因此，本研究基于长三角杭州中心国家参考气候站（NRCS，30.22°N，120.17°E；41.7ma.s.l.）一年（2013年）的连续测量，调查了微量气体（包括O3、NOx、NOy、SO2和CO）和颗粒物的季节特征、物种间关系以及当地排放和区域潜在源贡献。物质（PM2.5 和 PM10）。结果显示，该地区空气二级污染（光化学污染和雾霾污染）严重，O3（38天）和PM2.5（62天）频繁超标。 O3和PM2.5均表现出明显的季节变化，且模式相反：O3在温暖季节（5月和7月）达到最大值，而PM2.5在寒冷季节（11月至1月）达到最大值。种间相关性的总体结果表明，在挥发性有机化合物（VOC）限制的条件下，强烈的局部光化学有利于 O3 的产生，而在温暖的季节，它向最佳 O3 产生区移动，并伴随着高 O3 下二次细颗粒的形成。 PM2.5、CO、NOx 和 SO2 的排放图表明，在季节性范围内，当地排放对这些物种来说非常重要。通过使用后向轨迹模拟，进一步证实了内陆城市（浙江、江苏、安徽和江西省）之间的区域交通在季节尺度上对NRCS站点空气污染的关键作用。通过潜在源贡献函数（PSCF）分析，还发现黄海、东海和南海近海输送的气团与NRCS站点O3升高高度相关。光化学污染（O3）和雾霾（PM2.5）事件的案例研究都表明，当地大气光化学和天气条件在累积（与反气旋相关）和稀释过程（与气旋相关）过程中的综合重要性。除了补充长三角地区杭州市空气污染状况的概况外，本研究还具体阐明了当地排放和区域运输的作用，并解释了雾霾和光化学污染期间的物理和光化学过程。此外，这项工作表明跨区域的控制措施对于改善长三角地区的空气质量至关重要，并进一步强调了局部热诱导循环对空气质量的重要性。
Abstract. The Yangtze River Delta (YRD) is one of the most densely populated regions in China with severe air quality issues that have not been fully understood. Thus, in this study, based on 1-year (2013) continuous measurement at a National Reference Climatological Station (NRCS, 30.22° N, 120.17° E; 41.7 m a.s.l.) in the center of Hangzhou in the YRD, we investigated the seasonal characteristics, interspecies relationships, and the local emissions and the regional potential source contributions of trace gases (including O3, NOx, NOy, SO2, and CO) and particulate matter (PM2.5 and PM10). Results revealed that severe two-tier air pollution (photochemical and haze pollution) occurred in this region, with frequent exceedances in O3 (38 days) and PM2.5 (62 days). O3 and PM2.5 both exhibited distinct seasonal variations with reversed patterns: O3 reaching a maximum in warm seasons (May and July) but PM2.5 reaching a maximum in cold seasons (November to January). The overall results from interspecies correlation indicated a strong local photochemistry favoring the O3 production under a volatile organic compound (VOC)-limited regime, whereas it moved towards an optimum O3 production zone during warm seasons, accompanied by the formation of secondary fine particulates under high O3. The emission maps of PM2.5, CO, NOx, and SO2 demonstrated that local emissions were significant for these species on a seasonal scale. The contributions from the regional transport among inland cities (Zhejiang, Jiangsu, Anhui, and Jiangxi Province) on a seasonal scale were further confirmed to be crucial to air pollution at the NRCS site by using backward trajectory simulations. Air masses transported from the offshore areas of the Yellow Sea, East Sea, and South Sea were also found to be highly relevant to the elevated O3 at the NRCS site through the analysis of potential source contribution function (PSCF). Case studies of photochemical pollution (O3) and haze (PM2.5) episodes both suggested the combined importance of local atmospheric photochemistry and synoptic conditions during the accumulation (related with anticyclones) and dilution process (related with cyclones). Apart from supplementing a general picture of the air pollution state in the city of Hangzhou in the YRD region, this study specifically elucidates the role of local emission and regional transport, and it interprets the physical and photochemical processes during haze and photochemical pollution episodes. Moreover, this work suggests that cross-regional control measures are crucial to improve air quality in the YRD region, and it further emphasizes the importance of local thermally induced circulation for air quality.