2017—2019年中国337个城市及重点区域臭氧污染状况分析

分析了2017—2019年中国337城市O_3污染特征,结果表明:2017—2019年全国O_3第20～70百分位浓度逐年增幅相对稳定,第80～95百分位浓度逐年上升速率最快,平均每年升高5.5μg/m~3。全国O_3超标以轻度污染为主,主要集中在5—9月,占全年O_3超标天数的85.3%;"2+26"城市、汾渭平原交界、长三角、苏皖鲁豫交界O_3超标天数占全国63.9%,"2+26"城市O_3污染最为严重,平均每城市超标71 d。2017—2019年O_3单因子超标分别损失全国空气质量优良天数比例为4.5个百分点、4.9个百分点和7.4个百分点,2019年9月O_3单因子超标天数比例为18.8个百分点,单月使全年优良天数减少1.2个百分点。天津、河北、山东、北京、河南、山西、江苏的O_3污染相对较重,天津市发生O_3污染的关键温度为26～34℃,风速为2.0～2.5 m/s,相对湿度为40%～80%,降水明显减少和温度偏高是导致2019年O_3浓度升高的重要气象因素。     

Fast increasing of surface ozone concentrations in Pearl River Delta characterized by a regional air quality monitoring network during 2006-2011

Based on the observation by a Regional Air Quality Monitoring Network including 16 monitoring stations, temporal and spatial variations of ozone(O3), NO2and total oxidant(Ox) were analyzed by both linear regression and cluster analysis. A fast increase of regional O3concentrations of 0.86 ppbV/yr was found for the annual averaged values from 2006 to 2011 in Guangdong, China. Such fast O3increase is accompanied by a correspondingly fast NOx reduction as indicated by a fast NO2 reduction rate of 0.61 ppbV/yr. Based on a cluster analysis, the monitoring stations were classified into two major categories – rural stations(non-urban) and suburban/urban stations. The O3concentrations at rural stations were relatively conserved while those at suburban/urban stations showed a fast increase rate of 2.0 ppbV/yr accompanied by a NO2 reduction rate of 1.2 ppbV/yr. Moreover, a rapid increase of the averaged O3 concentrations in springtime(13%/yr referred to 2006 level) was observed, which may result from the increase of solar duration, reduction of precipitation in Guangdong and transport from Eastern Central China. Application of smog production algorithm showed that the photochemical O3production is mainly volatile organic compounds(VOC)-controlled. However, the photochemical O3production is sensitive to both NOx and VOC for O3pollution episode. Accordingly, it is expected that a combined NOx and VOC reduction will be helpful for the reduction of the O3 pollution episodes in Pearl River Delta while stringent VOC emission control is in general required for the regional O3 pollution control.     

北京市夏季近地层大气臭氧浓度的变化特征分析

臭氧是影响城市大气环境的重要污染气体之一,近地层臭氧主要是由人类活动所排放的NO和NMHC(非甲烷烃)等污染物在大气中经光化学过程产生.目前近地层臭氧浓度的形成和变化已成为大气环境研究的一个重要前沿课题.     

试点城市O3浓度特征分析

利用2009年O3试点城市的03监测数据,分析了北京、天津、上海、青岛、沈阳和广东的03浓度变化特征,统计了年超标情况,并结合气象要素数据分析了其对03浓度的影响.结果表明,不同城市各点位间03浓度变化趋势基本一致,但因点位类型不同,浓度存在差异；O3浓度呈单峰型日变化,在13:00-15:00出现最大值,6:00-7:00出现最小值；O3超标主要集中在4-8月份,广州和北京超标现象较多；O3浓度受温度、降水、风速和风向等气象要素影响较大.     

上海市城郊臭氧浓度变化分析及模拟预报

利用上海市普陀、南汇、淀山湖3个臭氧观测站2005年的臭氧小时观测资料,首先对市区和郊区的大气臭氧浓度的污染特征和变化情况进行了分析,结果表明,上海市郊区的臭氧浓度和污染水平高于市区,且臭氧浓度日变化在市区呈现明显的双峰现象,而郊区则是单峰型变化规律。然后运用基于统计学理论的最小二乘支持向量机（LSSVM）方法对3个站的日（24h）平均和白日（12h）平均以及日最大值臭氧浓度进行预测,得到较好的预报效果。     

A numerical study of summer ozone concentration over the Kanto area of Japan using the MM5/CMAQ model

We assessed the ability of the MM5/CMAQ model to predict ozone (O3) air quality over the Kanto area and to investigate the factors that a ect simulation of O3. We find that the coupled MM5/CMAQ model is a useful tool for the analysis of urban environmental problems. The simulation results were compared with observational data and were found to accurately replicate most of the important observed characteristics. The initial and boundary conditions were found to have a significant e ect on simulated O3 concentrations. The results show that on hot and dry days with high O3 concentration, the CMAQ model provides a poor simulation of O3 maxima when using initial and boundary conditions derived from the CMAQ default data. The simulation of peak O3 concentrations is improved with the JCAP initial and boundary conditions. On mild days, the default CMAQ initial and boundary conditions provide a more realistic simulation. Meteorological conditions also have a strong impact on the simulated distribution and accumulation of O3 concentrations in this area. Low O3 concentrations are simulated during mild weather conditions, and high concentrations are predicted during hot and dry weather. By investigating the e ects of di erent meteorological conditions on each model process, we find that advection and di usion di er the most between the two meteorological regimes. Thus, di erences in the winds that govern the transport of O3 and its precursors are likely the most important meteorological drivers of ozone concentration over the central Kanto area.     

北碚区臭氧浓度与气象因素相关性分析研究

本文以2017年重庆市北碚区臭氧浓度监测数据与气象条件数据进行分析,采用皮尔逊(Pearson)相关系数法来研究臭氧浓度与平均气温、相对湿度、风速和日照时间气象因素的相关性。统计分析得出,北碚区臭氧浓度与平均气温和日照时间呈强的正相关,与相对湿度呈强的负相关,与平均风速呈弱的正相关。     

High-resolution modeling and evaluation of ozone air quality of Osaka using MM5-CMAQ system

High-resolution modeling approach is increasingly being considered as a necessary step for improving the monitoring and predictions of regional air quality. This is especially true for highly urbanized region with complex terrain and land-use. This study uses Community Multiscale Air Quality (CMAQ) model coupled with MM5 mesoscale model for a comprehensive analysis to assess the suitability of such high-resolution modeling system in predicting ozone air quality in the complex terrains of Osaka, Japan. The 1-km and 3-km grid domains were nested inside a 9-km domain and the domain with 1-km grid covered the Osaka region. High-resolution Grid Point Value-Mesoscale Model (GPV-MSM) data were used after suitable validation. The simulated ozone concentrations were validated and evaluated using statistical metrics using performance criteria set for ozone. Daily maxima of ozone were found better simulated by the 1-km grid domain than the coarser 9-km and 3-km domains, with the maximum improvement in the mean absolute gross error about 3 ppbv. In addition, 1-km grid results fared better than other grids at most of the observation stations that showed noticeable di erences in gross error as well as correlation. These results amply justify the use of the integrated high-resolution MM5-CMAQ modeling system in the highly urbanized region, such as the Osaka region, which has complex terrain and land-use.     

臭氧污染对不同品种小麦养分吸收与分配的影响

近地层臭氧(O3)污染会危害植物生长,势必间接影响氮素吸收利用.本研究利用开放式臭氧污染(Free-air O3 concentration enrichment,O3FACE)研究平台,研究了大气O3浓度增加(比周围大气高50％)对长江三角洲地区5个冬小麦(Tritcium aestivum L.)主栽品种(扬麦15、扬麦16、烟农19、扬幅麦2号和嘉兴002)的物质积累、氮素吸收与分配的影响.结果显示,O3浓度升高对秸秆和籽粒的影响远大于根系.烟农19、嘉兴002和扬麦16的产量因O3浓度升高而减少,而扬麦15和扬幅麦2号产量则变化不大.扬幅麦2号与嘉兴002的秸秆干物重因O3浓度升高而显著增加,扬麦15与烟农19分别呈增大与降低趋势,而扬麦16则无变化表明O3污染对小麦干物质积累与分配的影响存在品种差异.O3浓度升高影响氮素在小麦根、秸秆和籽粒中的含量与分配趋势,但影响程度因品种而异.O3浓度升高导致扬幅麦2号的总吸氮量显著增加30.6％及烟农19的总吸氮量呈增加趋势,并使嘉兴002的总吸氮量显著降低34.8％及扬麦16总吸氮量呈降低趋势,但扬麦15的总吸氮量则不受影响.除扬麦15外,O3浓度升高具有减少籽粒氮占总氮比例的趋势,表明小麦响应O3污染对氮素吸收与分配调整机制存在品种差异.扬麦16、烟农19和嘉兴002的氮肥偏生产力因O3浓度升高而显著降低,而扬麦15和扬幅麦2号则无明显变化.扬麦16和嘉兴002的氮肥利用率因O3浓度升高显著降低,而扬幅麦2号呈增加趋势,扬麦15、烟农19呈降低趋势.综合来看,小麦扬麦15抗O3污染能力强于其它品种,而嘉兴002则最易遭受臭氧污染危害.评价O3污染对小麦干物质与产量的形成与分配、氮素在植物-土壤系统周转的影响应综合考虑品种差异.