Observation of regional air pollutant transport between the megacity Beijing and the North China Plain
Observation of regional air pollutant transport between the megacity Beijing and the North China Plain
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DOI：
10.5194/acp-16-14265-2016
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发表时间：
2016-11
影响因子：
6.3
通讯作者：
Yingruo Li;C. Ye;Jun Liu;Yi Zhu;Junxia Wang;Z. Tan;Weili Lin;L. Zeng;T. Zhu
中科院分区：
文献类型：
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作者：
Yingruo Li;C. Ye;Jun Liu;Yi Zhu;Junxia Wang;Z. Tan;Weili Lin;L. Zeng;T. Zhu
摘要。特大城市通过空气污染物的运输与周边地区有很强的相互作用。人们经常提到，北京的空气质量受到来自华北平原的空气污染物的影响。估算北京与北京之间的空气污染物跨境运输对空气质量管理具有重要意义。然而，利用长期观测对跨界运输的评价是非常有限的。利用2006年8月至2008年10月在特大城市北京与中央气象站交界的榆发站点的SO2、NO、NO2、O3和CO等气态污染物的观测结果，结合气象参数，探讨了2006 - 2008年北京及周边地区空气质量研究运动（CAREBeijing 2006 - 2008）中榆发地区输送通量强度的评估方法。在观测期间，SO2、NO、NO2、NOx、O3、Ox和CO的小时平均值±SD（中位数）浓度分别为15±16 (9)ppb、12±25 (3)ppb、24±19 (20)ppb、36±39 (23)ppb、28±27 (21)ppb、52±24 (45)ppb和1.6±1.4 (1.2)ppm。双变量极坐标图显示了污染物浓度对风速和风向的依赖关系，从而推断出它们的主要输送方向。地表通量强度计算进一步证实了北京和新冠肺炎对榆发的区域运输影响。观测期内，SO2、NO、NO2、NOx、O3、Ox和CO的净地表输送通量强度（平均±SD）分别为6.2±89.5、−4.3±29.5、−0.6±72.3、−4.9±93.0、14.7±187.8、14.8±234.9和70±2830µg s−1 m−2。对于SO2、CO、O3和Ox，除冬季外，NCP到榆发的地表通量强度均超过北京到榆发的地表通量强度，其中夏季净通量最大，约为其他季节的4-8倍。除夏季外，北京至榆发的NOx地表输送通量强度均强于NCP至榆发的地表输送通量，其中冬季净通量最强，约为其他季节的1.3 ~ 8倍。然后在势源贡献函数分析（PSCF）中将通量强度分配到相应的轨迹上，验证了通量强度的计算结果。我们的研究还表明，风场、排放清单和光化学反应等多种因素可能影响空气污染物的运输。奥运会期间地表通量强度的下降暗示了地方减排和区域合作对成功的空气质量管理的作用。为了进一步全面讨论北京与北京之间的区域交通，需要三维观测。
Abstract. Megacities have strong interactions with the surrounding regions through transport of air pollutants. It has been frequently addressed that the air quality of Beijing is influenced by the influx of air pollutants from the North China Plain (NCP). Estimations of air pollutant cross-boundary transport between Beijing and the NCP are important for air quality management. However, evaluation of cross-boundary transport using long-term observations is very limited. Using the observational results of the gaseous pollutants SO2, NO, NO2, O3, and CO from August 2006 to October 2008 at the Yufa site, a cross-boundary site between the megacity Beijing and the NCP, together with meteorological parameters, we explored a method for evaluating the transport flux intensities at Yufa, as part of the “Campaign of Air Quality Research in Beijing and Surrounding Region 2006–2008” (CAREBeijing 2006–2008). The hourly mean ± SD (median) concentration of SO2, NO, NO2, NOx, O3, Ox, and CO was 15 ± 16 (9) ppb, 12 ± 25 (3) ppb, 24 ± 19 (20) ppb, 36 ± 39 (23) ppb, 28 ± 27 (21) ppb, 52 ± 24 (45) ppb, and 1.6 ± 1.4 (1.2) ppm during the observation period, respectively. The bivariate polar plots showed the dependence of pollutant concentrations on both wind speed and wind direction, and thus inferred their dominant transport directions. Surface flux intensity calculations further demonstrated the regional transport influence of Beijing and the NCP on Yufa. The net surface transport flux intensity (mean ± SD) of SO2, NO, NO2, NOx, O3, Ox, and CO was 6.2 ± 89.5, −4.3 ± 29.5, −0.6 ± 72.3, −4.9 ± 93.0, 14.7 ± 187.8, 14.8 ± 234.9, and 70 ± 2830 µg s−1 m−2 during the observation period, respectively. For SO2, CO, O3, and Ox the surface flux intensities from the NCP to Yufa surpassed those from Beijing to Yufa in all seasons except winter, with the strongest net fluxes largely in summer, which were about 4–8 times those of other seasons. The surface transport flux intensity of NOx from Beijing to Yufa was stronger than that from the NCP to Yufa except in summer, with the strongest net flux in winter, which was about 1.3–8 times that of other seasons. The flux intensities were then assigned to the corresponding trajectories in the potential source contribution function analysis (PSCF), which confirmed the results of flux intensity calculations. Our study also suggested that various factors, such as the wind field, emission inventory, and photochemical reactions, could influence transport of air pollutants. The decrease of surface flux intensity during the Olympic Games implied the role of both local emission reduction and regional cooperation in successful air quality management. Three dimensional observations are needed for further comprehensive discussion of the regional transport between Beijing and the NCP.