珠江三角洲秋季典型光化学污染过程中的臭氧来源分析

利用区域空气质量模型CAMx 模拟珠江三角洲地区(简称珠三角) 2009 年11 月臭氧浓度演变过程, 运用臭氧源识别技术(OSAT)对其中两个典型的光化学污染日进行臭氧来源识别, 并与清洁日的情况做对照分析。结果表明, 广州市区和东莞的排放对本地及珠三角西南部臭氧贡献很大(15~30 μL/m3), 深圳宝安区排放对珠江口有明显的贡献(15~25 μL/m3)。流动源和溶剂使用源是珠三角臭氧生成最主要的两类前体物排放源, 主要影响范围覆盖珠三角的中部和西部, 流动源对佛山和江门交界地区的臭氧小时浓度贡献可达50 μL/m3。较高的边界外传输使得珠三角在出现不利污染气象条件的情况下更易发生臭氧污染, 但珠三角的前体物排放是造成污染时段臭氧浓度升高的主要原因, 控制珠三角内的污染源排放对控制臭氧污染具有关键作用。

Ozone Source Apportionment of Typical Photochemical Pollution Episodes in the Pearl River Delta in Autumn

The Comprehensive Air Quality Model with extensions (CAMx), a 3-D regional chemical transport model, was used to simulate ozone concentrations in the Pearl River Delta (PRD) in November, 2009. Ozone Source Apportionment Technology (OSAT) was applied to investigate sources of two typical ozone episodes and a clean day as comparison. The results showed that emissions from urban Guangzhou and Dongguan mainly contributed to local areas and the southwestern part of PRD (15–30 μL/m3), while emissions from Shenzhen Baoan district (15–25 μL/m3) mainly affected the Pearl River Estuary. Mobile sources and solvent usage sources were two major contributors to ozone formation and had an influence in most areas of the central and western PRD. Mobile sources could contribute as much as 50 μL/m3 hourly ozone concentration to the boarding area of Foshan and Guangzhou. Trans-boundary import of ozone made episodes more likely to occur in PRD under unfavorable weather conditions, however, the ozone precursors emitted within the PRD region were the main cause of high ozone concentrations during ozone episodes. As a result, the strategies on controlling emissions within the PRD region are the key to the reduction of ozone pollutions in PRD.