由于最近地面臭氧的增长和挥发性有机化合物(VOC)的排放增加,VOC排放控制已成为中国关注的主要问题。作为回应,最近的政策规定了控制VOC的排放上限,但是很少有人受到PM2.5和臭氧共同控制目标的限制,并讨论了影响排放帽制定的因素。在这里,我们通过一种新的响应面建模(RSM)技术,提出了一个量化受PM2.5和臭氧目标约束的VOC排放帽的框架,实现量化的50%的计算成本节省。在珠江三角洲(PRD)地区,受空气质量目标限制的VOC排放上限随着NOx减排水平的变化而变化很大。如果不考虑珠三角地区周边地区的控制措施,VOC排放上限可以有两种可行的策略来实现空气质量目标(对于最大8小时平均90百分位数(MDA8-90%)的臭氧为160µg/m3,对于年平均PM2.5为25µg/m3):适度的VOC排放上限,NOx减排量<20%,或明显的VOC排放上限,NOx减排量>60%。如果将臭氧浓度目标降低到155µg/m3,则深度减少NOx排放是珠三角唯一可行的臭氧控制措施。基于蒙特卡罗模拟的季节性VOC排放上限的优化可以使我们获得更高的臭氧收益或更大的VOC减排量。如果挥发性有机化合物的排放量在秋季进一步减少,MDA8-90%臭氧可降低0.3-1.5µg/m3,相当于10%VOC减排措施的臭氧益处。本研究提出的VOC排放上限量化和优化方法可为我国区域PM2.5和O3污染的协调控制提供科学指导。
Because of the recent growth in ground-level ozone and increased emission of volatile organic compounds (VOCs), VOC emission control has become a major concern in China. In response, emission caps to control VOC have been stipulated in recent policies, but few of them were constrained by the co-control target of PM2.5 and ozone, and discussed the factor that influence the emission cap formulation. Herein, we proposed a framework for quantification of VOC emission caps constrained by targets for PM2.5 and ozone via a new response surface modeling (RSM) technique, achieving 50% computational cost savings of the quantification. In the Pearl River Delta (PRD) region, the VOC emission caps constrained by air quality targets varied greatly with the NOx emission reduction level. If control measures in the surrounding areas of the PRD region were not considered, there could be two feasible strategies for VOC emission caps to meet air quality targets (160 µg/m3 for the maximum 8-hr-average 90th-percentile (MDA8-90%) ozone and 25 µg/m3 for the annual average of PM2.5): a moderate VOC emission cap with <20% NOx emission reductions or a notable VOC emission cap with >60% NOx emission reductions. If the ozone concentration target were reduced to 155 µg/m3, deep NOx emission reductions is the only feasible ozone control measure in PRD. Optimization of seasonal VOC emission caps based on the Monte Carlo simulation could allow us to gain higher ozone benefits or greater VOC emission reductions. If VOC emissions were further reduced in autumn, MDA8-90% ozone could be lowered by 0.3-1.5 µg/m3, equaling the ozone benefits of 10% VOC emission reduction measures. The method for VOC emission cap quantification and optimization proposed in this study could provide scientific guidance for coordinated control of regional PM2.5 and O3 pollution in China.