Li Kangwei, Chen Linghong, White Stephen J, Zheng Xianjue, Lv Biao, Lin Chao, Bao Zhier, Wu Xuecheng, Gao Xiang, Ying Fang, Shen Jiandong, Azzi Merched, Cen Kefa
State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China; CSIRO Energy, PO Box 52, North Ryde, NSW 1670, Australia.
State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China.
Environ Pollut. 2018 Jan;232:42-54. doi: 10.1016/j.envpol.2017.09.016. Epub 2017 Sep 19.
During the 2016 Hangzhou G20 Summit, the chemical composition of submicron particles (PM) was measured by a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) along with a suite of collocated instruments. The campaign was undertaken between August 5 and September 23, 2016. The impacts of emission controls and meteorological conditions on PM chemical composition, diurnal cycles, organic aerosol (OA) source apportionment, size distribution and elemental ratios were characterized in detail. Excluding rainy days, the mean PM mass concentration during G20 was 30.3 μg/m, similar to that observed before G20 (28.6 μg/m), but much lower than that after G20 (42.7 μg/m). The aerosol chemistry during the three periods was substantially different. Before G20, high PM loading mostly occurred at daytime, with OA accounting for 60.1% of PM, followed by sulfate (15.6%) and ammonium (9.1%). During G20, the OA fraction decreased from 60.1% to 44.6%, whereas secondary inorganic aerosol (SIA) increased from 31.8% to 49.5%. After G20, SIA dominated high PM loading, especially at nighttime. Further analysis showed that the nighttime regional transport might play an unfavorable role in the slight increase of secondary PM during G20, while the strict emissions controls were implemented. The OA (O/C = 0.58) during G20 was more aged, 48.7% and 13.7% higher than that before and after G20 respectively. Our study highlighted that the emission controls during G20 were of great success in lowering locally produced aerosol and pollutants, despite of co-existence of nighttime regional transport containing aerosol high in low-volatile organics and sulfate. It was implied that not only are emissions controls on both local and regional scale important, but that the transport of pollutants needs to be sufficiently well accounted for, to ensure the successful implementation of air pollution mitigation campaigns in China.
在2016年杭州二十国集团（G20）峰会期间，利用高分辨率飞行时间气溶胶质谱仪（HR-ToF-AMS）以及一系列配套仪器对亚微米颗粒物（PM）的化学成分进行了测量。该监测活动于2016年8月5日至9月23日开展。详细研究了排放控制和气象条件对PM化学成分、日变化周期、有机气溶胶（OA）源解析、粒径分布和元素比率的影响。排除雨天，G20峰会期间PM的平均质量浓度为30.3μg/m³，与G20峰会前观测到的浓度（28.6μg/m³）相似，但远低于G20峰会后（42.7μg/m³）。这三个时期的气溶胶化学性质存在显著差异。G20峰会前，高PM负荷大多出现在白天，其中OA占PM的60.1%，其次是硫酸盐（15.6%）和铵盐（9.1%）。在G20峰会期间，OA所占比例从60.1%降至44.6%，而二次无机气溶胶（SIA）从31.8%增至49.5%。G20峰会后，SIA在高PM负荷中占主导地位，尤其是在夜间。进一步分析表明，在实施严格排放控制的情况下，夜间区域传输可能对G20峰会期间二次PM的轻微增加起到了不利作用。G20峰会期间的OA（O/C = 0.58）老化程度更高，分别比G20峰会前和后高出48.7%和13.7%。我们的研究强调，尽管存在含有低挥发性有机物和气态硫酸盐的夜间区域传输，但G20峰会期间的排放控制在降低本地产生的气溶胶和污染物方面取得了巨大成功。这意味着不仅地方和区域尺度上的排放控制很重要，而且污染物的传输也需要得到充分考虑，以确保中国空气污染减排行动的成功实施。
