臭氧253.65nm吸收截面系数变化对中国环境空气质量达标的影响

臭氧253.65 nm波长处的吸收截面系数通过朗伯-比尔定律被普遍用于紫外吸收原理臭氧测量，是直接影响臭氧监测数据的基础参数.国际计量局重新测定并于2019年修订了臭氧253.65 nm处的吸收截面系数，拟从1.147×10-17 cm2/mol降至1.132 9×10-17 cm2/mol，将导致臭氧监测浓度系统性升高1.24%.为研究臭氧吸收截面系数变化对中国环境空气质量达标的影响，使用2018年中国国家环境空气监测网臭氧监测数据模拟了特征吸收截面变化后中国337个地级及以上城市的臭氧监测数据，并统计了特征吸收截面变化对全国以及重点城市群臭氧超标城市数量、臭氧污染天数和优良天数比例的影响.结果表明:臭氧吸收截面系数的变化将导致全国臭氧超标城市增加7个；全国以及"2+26"城市群、长三角城市群、珠三角城市群、汾渭平原城市群中各城市臭氧超标天数分别增加1.4、3.5、2.4、1.7和2.1 d，优良天数比例分别降低0.3%、0.9%、0.6%、0.4%和0.6%.研究显示，臭氧吸收截面系数变化将系统性影响全国以及重点地区环境空气质量达标工作，应予以重点关注. 

Influence of Updated Absorption Cross-Section Coefficient of Ozone at 253.65 nm on Environmental Air Quality Compliance in China

UV photometric ozone measurements rely on the Beer-Lambert law of ozone absorption cross section at 253.65 nm. Bureau International des Poids et Mesures (BIPM) re-measured and revised the ozone absorption cross section at 253.65 nm from 1.147×10-17 cm2/mol to 1.1329×10-17 cm2/mol. This change will cause a systematic increase in ozone monitoring concentration by 1.24%. In order to assess the change on the air quality compliance in China, we used the national ambient air ozone monitoring data of 337 major cities in 2018 to simulate the impact of the new absorption cross section at 253.65 nm to the ozone concentration, and calculated the number of non-compliant cities, number of days with ozone pollution and the annual rate of days with good air quality in China. The results indicated that: (1) The change in the ozone absorption cross sectional coefficient will lead to an increase of 7 cities in the country that exceed the ozone standard. (2) The number of days of ozone pollution in the country, the cities in the '2+26' area, the Yangtze River Delta area, the Pearl River Delta and the Fenhe-Weihe Plain will be increased by 1.4, 3.5, 2.4, 1.7 and 2.1 days per city, respectively. (3) The proportion of the days with good air quality in these cities will be reduced by 0.3%, 0.9%, 0.6%, 0.4% and 0.6% annually. Considering the impact of the new absorption cross section on the air quality compliance in China, scientists and the government should pay more attention to the changes in the ozone absorption cross section.