粤东北地区秋季臭氧来源解析与生成敏感性研究

Study on Ozone Source and Its Generating Sensitivity in Northeastern Guangdong during Autumn

秋季是广东省臭氧污染最严重的季节,利用三维空气质量模型对粤东北城市梅州空气污染进行模拟与评估,综合运用多种手段深入研究臭氧污染过程与臭氧生成敏感性及定量臭氧的来源。在偏东北气流的作用下,尽管风速较大,但因日照较强,臭氧生成旺盛,污染比较严重。梅州秋季臭氧大部分为背景浓度,午后约达60%,本地排放贡献10%,午后最高约10μg/m^3,外地排放贡献30%,江西与福建两省午后最高约23与11μg/m^3,广东省其它城市的贡献率不足1μg/m^3。按排放源分类,对梅州市秋季臭氧浓度贡献最大为火电、工业高架源与飞机排放,午后臭氧贡献达17~20μg/m^3。秋季,梅州市区臭氧生成敏感性历经早上的NOx敏感区到中午的VOCs敏感区,最后为傍晚的NO_x敏感区阶段。全天平均而言,秋季臭氧主要是在VOCs敏感区内生成。要控制粤东北的臭氧污染,在秋季要重点控制北面省市的火电、工业高架源等,同时加强对VOCs的控制。

Ozone pollution in Guangdong Province was much more serious in autumn. In this paper, air pollution in Meizhou, a city in northeast Guangdong was simulated and evaluated by the 3-dimensional air quality model, ozone- generating process and sensitivity were studied, and the source apportionment was quantified by a variety of comprehensive means. Influenced by northeast wind, despite its higher wind speed, ozone-generation became active due to the strong sunshine. In Meizhou City, major part of the ozone concentration in autumn, up to 60% in the afternoon was due to the local background ozone, and the local emissions contributed about 10%, the maximum was about 10 μg/m3 in the afternoon, on the other hand, the external emissions contributed 30%, of them the maximum contributions of Jiangxi and Fujian provinces were 23 and 11μg/m3 respectively, while the contribution of other cities in Guangdong Province was less than 1 μg/m3. Regarding the sources categories, power plants and elevated industrial source as well as aircraft emissions constituted the largest contribution to autumn ozone concentration, ca 1-20 μg/m3. In autumn, the ozone-generating sensitivity shifted from NOx sensitive in the morning to VOCs sensitive at noon, and finally turned into NOx sensitive at sunset. As far as the daily average, ozone was mainly generated in the VOCs sensitive zone. In conclusion, to reduce ozone pollution in northeastern Guangdong, it was important to curb emissions from power plants and elevated industrial sources in the north, meanwhile to control VOCs pollution too.