- Variation characteristics and potential sources of air pollutants during 2014-2017 in Wuhan
- 摘要：利用武汉市2014—2017年大气污染物（SO2、NO2、CO、O3、PM2.5和PM10）和气象要素的观测数据，分析了大气污染物的变化特征及其影响因素.使用HYSPLIT模式计算了影响武汉市的主要气团类型，并利用潜在源区贡献（PSCF）和浓度权重轨迹（CWT）分析方法，揭示了研究期内武汉市不同大气污染物的潜在源区分布及其贡献特性.结果表明，武汉市2014—2017年空气质量逐年好转，SO2、O3、PM2.5和PM10的浓度呈逐年下降的趋势，但NO2和CO的浓度先下降后上升.2017年SO2、O3、PM2.5、PM10、NO2和CO的浓度分别为9.6、50.8、52.7、89.2、47.5 μg·m-3和1.1 mg·m-3，分别比2014年降低了64.3%、23.0%、24.7%、18.8%、3.5%和5.9%.大气污染物存在显著的季节变化和月变化.大气污染物在四个季节中日变化类似，SO2和O3均为单峰型分布，NO2、CO、PM2.5和PM10均为双峰型分布.武汉市空气污染以PM2.5为主，随着污染程度的加剧PM2.5/PM10的值逐渐增大，在空气质量为严重污染时，PM2.5/PM10高达90%，比空气质量为优时高了31.34%.局地气团（45%）和来自山西、陕西和河南一带的西北气团（12.1%）下大气污染物浓度较高.大气污染物的潜在源区贡献（WPSCF）和浓度权重轨迹（WCWT）的较大值主要集中在武汉市本地及其周边地区，局地污染对武汉市大气污染物的贡献较大，但不同大气污染物受到排放源分布和停留时间等影响其WPSCF和WCWT的分布范围不同.
- Abstract：Air pollutants (SO2, NO2, CO, O3, PM2.5 and PM10) and meteorological elements during 2014-2017 in Wuhan were used together to analyze the air pollutants' variation feature and their influencing factors. The major types of air masses influencing Wuhan were derived by using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) modeling system. Additionally, the distributions of potential source region and their contribution fractions for different air pollutants were derived by using the methods of the potential source contribution function (PSCF) and the concentration weighted trajectory (CWT). Results show that the air quality improved from 2014 to 2017, the concentrations of SO2, O3, PM2.5, and PM10 show an overall decrease gradually while the NO2 and CO show a short decrease then followed by an increase from 2014 to 2017. The annual concentrations of SO2, O3, PM2.5, PM10, NO2, and CO were 9.6, 50.8, 52.7, 89.2, 47.5 μg·m-3, and 1.1 mg·m-3 in 2017, which dropped by 35.7%, 77.0%, 75.3%, 81.2%, 96.5% and 94.1% compared with those in 2014, respectively. The air pollutants exhibited significant seasonal and monthly variations. The diurnal variations of air pollutants were similar in four seasons, with unimodal distributions for SO2 and O3 and bimodal distributions for NO2, CO, PM2.5 and PM10. The air pollution in Wuhan was still dominated by fine particulate matter. The ratio of PM2.5/PM10 enhanced with the deterioration of air quality and can reach as high as 0.9 when the air quality status was seriously polluted (air quality index (AQI) >300), which increased by 31.34% compared with the ratio when the air quality was excellent (0 < AQI < 50). Air pollutants, which were influenced by local air masses (45%) and northwestern air masses (12.1%) originated from Shanxi, Shanxi and Henan, had relatively high concentrations. High values of the pollutant WPSCF (weighted potential source contribution function) and WCWT (weighted concentration-weighted trajectory) were mainly centralized in local and surrounding regions, demonstrating that the local pollution had greater contributions to pollutants concentrations in Wuhan. However, the distribution scope of WPSCF and WCWT varied with different pollutants, which was due to the various emission sources and different resident time of pollutants.