Spatial and Temporal Variability of the PM2.5/PM10 Ratio in Wuhan, Central China
Spatial and Temporal Variability of the PM2.5/PM10 Ratio in Wuhan, Central China
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DOI：
10.4209/aaqr.2016.09.0406
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发表时间：
2017-03-01
影响因子：
4
通讯作者：
Tang, Xin
中科院分区：
文献类型：
--
作者：
Xu, Gang;Jiao, Limin;Tang, Xin
细颗粒物(PM2.5)和粗颗粒物(PM2.5-10)一般来自不同的来源，因此PM2.5/PM10比值显示出颗粒物污染的特征。在没有直接测量的情况下，该比率可以用来表征基本的大气过程和评估历史上的PM2.5污染。然而，由于PM浓度在时间和空间上的变化很大，因此比率的应用需要不同的模式。收集了武汉市城区(市区)9个监测点和武汉市1个偏远背景点2013-2015年PM2.5和PM10逐时观测数据，分析了城市尺度上PM2.5和PM10比值的长期、短期时间变化和空间分布、空间差异。结果表明，市区PM2.5/PM10年平均比值为0.62，背景区为0.68，具有明显的季节、月和日变化。由于大气条件稳定，这一比例在冬季达到最大。这一比值的日变化具有明显的昼夜差异，由于逆温的影响，各季节的比值在夜间增大，白天减小，午后温和升高。我们发现，这一比率存在明显的空间梯度，从城市核心到城市边缘再到郊区逐渐增加。本研究进一步揭示了PM2.5/PM10比值的时空变异性。研究表明，PM2.5/PM10在实际应用中应注意其变异性。
Fine particles (PM2.5) and coarse particles (PM2.5-10) are generally produced by different sources, so the PM2.5/PM10 ratio reveals characteristics of particle pollution. The ratio can be used to characterize the underlying atmospheric processes and evaluate historical PM2.5 pollution in absence of direct measurements. However, application of the ratio needs its varying pattern because PM concentrations change significantly at time and space. Hourly PM2.5 and PM10 observations at nine monitoring sites in urban area (Urban-sites) and one remote Background-site in Wuhan in 2013-2015 were collected to investigate both long-term, short-term temporal variation and spatial distribution, spatial disparity of the ratio at a city scale. The results show that annual average PM2.5/PM10 ratio is 0.62 at Urban-sites and 0.68 at Background-site with apparent seasonal, monthly and daily variations. The ratio reaches the maximum in winter because of stable atmospheric conditions. There are apparent night-day differences of daily variation of the ratio, which increases at night in all seasons in consequence of temperature inversion and declines in the daytime with a moderate rise in the afternoon. We find obvious spatial gradients of the ratio that gradually increases from urban core to urban fringe and to suburban. This study provides further insights to the spatio-temporal variability of PM2.5/PM10 ratio. The evidence indicates that the variability of PM2.5/PM10 should be noticed in its applications.