摘要
明确臭氧(O_(3))与前体物的非线性关系是O_(3)防控措施制定的基础和关键.基于北京城区站点2020年4~9月O_(3)、挥发性有机物(VOCs)、氮氧化物(NO_(x))和气象要素在线观测,分析了O_(3)及其前体物污染特征,利用随机森林(RF)模型结合SHAP值探究了影响O_(3)的关键因素,并通过多情景分析探讨了O_(3)-VOCs-NO_(x)敏感性.相关性分析结果显示O_(3)小时浓度与温度(T)呈显著正相关,与TVOCs和NO_(x)呈显著负相关;但从每日结果来看,O_(3)与T、TVOCs和NO_(x)均呈显著正相关.RF模型模拟的O_(3)浓度与实测值吻合较好,进一步计算了各个特征变量的SHAP值,结果显示T和NO_(x)对O_(3)影响最高,但前者是正向影响,而后者是负向影响.以观测期间O_(3)污染天的NO_(x)和VOCs平均值为基础情景,设置了对应不同NO_(x)和VOCs的多种情景,并利用RF模型计算不同情景下的O_(3),得到O_(3)等值线(EKMA曲线),结果显示北京城区O_(3)-VOCs-NO_(x)敏感性处于VOCs控制区,与基于观测的盒子模型(OBM)得到的结果一致,这说明RF模型可以用作O_(3)-VOCs-NO_(x)敏感性分析的一种补充方法.
The basis and key step to developing ozone(O_(3))prevention and control measures is determining the non-linear relationship between O_(3) and its precursors.Based on online observations of O_(3),volatile organic compounds(VOCs),nitrogen oxides(NO_(x)),and meteorological elements from April to September 2020 at an urban site in Beijing,we analyzed the pollution characteristics of O_(3) and its precursors,explored key factors affecting O_(3) using the random forest(RF)model combined with SHAP values,and explored the O_(3)-VOCsNO_(x) sensitivity through a multi-scenarios analysis.The results of correlation analysis showed that the hourly concentration of O_(3) was significantly positively correlated with temperature(T)and negatively correlated with TVOCs and NO_(x).However,in terms of the daily values,O_(3) was significantly positively correlated with T,TVOCs,and NO_(x).The simulated O_(3) values by the RF model agreed with the measured values.The SHAP values of each characteristic variable were further calculated.The results suggested that T and NO_(x) showed the two highest effects on O_(3),with positive and negative values,respectively.Based on the average NO_(x) and VOCs on O_(3) pollution days during the observation period(the base scenario),multi-scenarios with different NO_(x) and VOCs were set up.The RF model was used to calculate O_(3) under different scenarios and obtain the O_(3) isopleth(EKMA curve).The results showed that the O_(3)-VOCs-NO_(x) sensitivity in urban areas of Beijing was in the VOCs-limited regime,which was consistent with the results obtained from the observation-based box model(OBM).This indicated that the RF model could be used as a complementary method for O_(3)-VOCs-NO_(x) sensitivity analysis.
作者
周红
王鸣
柴文轩
赵昕
ZHOU Hong;WANG Ming;CHAI Wen-xuan;ZHAO Xin(Collaborative Innovation Center of Atmospheric Environment and Equipment Technology,Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control,School of Environmental Science and Engineering,Nanjing University of Information Science&Technology,Nanjing 210044,China;China National Environmental Monitoring Centre,Beijing 100012,China;Nanjing Intelligent Environmental Science and Technology Co.,Ltd.,Nanjing 211800,China)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2024年第5期2497-2506,共10页
Environmental Science
基金
国家自然科学基金项目(41505113)。
