上海市PM2.5和臭氧协同污染案例的控制路径模拟研究
Simulation study of emission control strategies for the case of co-pollution of PM2.5 and ozone in Shanghai
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摘要: 近年来,我国多项污染物浓度均有所降低,但是臭氧(O3)改善幅度远小于细颗粒物(PM2.5),PM2.5和O3共同污染情况也有发生。为制定针对PM2.5和O3在共污染日的浓度削峰方案,以上海市2018年4月27日—30日PM2.5和O3同超标时段为研究对象,利用三维气象-空气质量模型,对上海市人为源NOx和挥发性有机化合物(VOCs)的减排效果进行模拟。结果显示,上海市O3日最大八小时滑动平均值(MDA8)的峰值率(PR)为0.6~1.1,整体处于VOCs控制区,为实现上海市MDA8 O3浓度不反弹,VOCs/NOx减排比需控制在1.9:1以上。污染物的区域传输,SOA对前体物的响应及NO3-的昼夜生成差异是PM2.5减排过程中的关键影响因素。相比于上海市的独立减排,提前减排和区域联合减排均可以进一步使上海MDA8 O3浓度降低,降幅为0.6%~3.0%。区域减排可有效降低下风向江苏西南部城市的PM2.5浓度,由于上海及部分地区PM2.5中的二次无机组分浓度上升,导致PM2.5浓度小幅升高。提前减排比区域减排更有效地降低上海市PM2.5浓度。为使MDA8 O3和PM2.5浓度均得到有效削减,应根据不同区域VOCs和NOx的实际排放情况以及气象条件来制定科学合理的协同减排方案,对VOCs和NOx的排放进行科学的减排比例控制。为实现PM2.5浓度有效降低,也需要关注一次颗粒物和其他气态前体物(如SO2、NH3)的排放。
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关键词:
- 臭氧(O3) /
- PM2.5 /
- 区域多尺度空气质量(CMAQ)模型 /
- 减排情景
Abstract: In recent years, the concentrations of multiple air pollutants in China have been reduced yet the reduction of surface ozone (O3) concentration is not satisfactory compared to that of fine particulate matter (PM2.5). The co-occurrence of PM2.5 and O3 pollution has occurred from time to time. To develop emission reduction strategy for PM2.5 and O3 on concurrent pollution days, the emission reduction effects of anthropogenic NOx and volatile organic compounds (VOCs) in Shanghai were simulated using a three-dimensional meteorological-air quality model for the period of April 27—30, 2018, when PM2.5 and O3 both exceeded the national standard in Shanghai. Simulation results show that Shanghai was mostly under VOCs-controlled during the modeling period with a peak ratio (PR) of 0.6-1.1 in terms of the maximum daily eight-hour average (MDA8) O3. A VOCs/NOx reduction ratio (VNr) of at least 1.9:1 is needed to prevent ozone increase during emission reduction maintain the MDA8 O3 concentration in Shanghai. For the reduction of PM2.5 concentration, regional transport, SOA response to precursors and the diurnal variations in NO3- production are important factors. Compared to the local emission reduction in Shanghai, both emission reduction advanced in time and jointly in region can further reduce the MDA8 O3 concentration in Shanghai by 0.6%-3.0%. However, under the regional emission reduction scenario, PM2.5 concentration in the downwind (i.e. southwestern Jiangsu) can be effectively reduced whereas PM2.5 concentration slightly increased in Shanghai due to increases of the secondary inorganic components in PM2.5. Advanced emission reduction (by three days ahead of pollution days) is more effective than regional reduction in terms of reducing PM2.5 concentration in Shanghai. In order to effectively reduce both MDA8 O3 and PM2.5 concentrations, the emission reduction plan should be consider the local emissions of VOCs and NOx in different regions as well as the meteorological conditions. To effectively achieve reductions inPM2.5 concentration, attention also needs to be paid to the emission reduction of primary particulate matter and other gaseous precursors (e.g. SO2, NH3).
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