北京城区PM_(2.5)及主要污染气体“周末效应”和“假日效应”研究

利用2009—2012年北京城区海淀宝联站6种污染物(PM2.5、NO、NO2、O3、CO和SO2)的连续监测数据,研究了污染物浓度的周循环变化规律,以及春节、国庆节假日期间和假日前后污染物浓度变化的差异.结果表明,北京城区O3浓度存在周末高于工作日的显著"周末效应"现象,其它污染物则表现出周末低于工作日的"周末效应"现象;国庆节较长假期存在与"周末效应"相类似的"假日效应",即假日期间污染物浓度明显低于非假日期间(O3相反).而春节期间PM2.5、CO、SO2出现"反常"浓度(污染物浓度在假日期间高于非假日期间),可能与春节期间烟花爆竹燃放有关.从污染物浓度日变化特征分析,污染物浓度高峰期与人类活动高峰期时间基本一致,而污染物在周末和工作日出现的浓度差异现象也与人类活动的周循环差异现象相吻合,NO、NO2和CO的小时平均浓度在周末和工作日的最大偏差出现在08:00,分别为-19.8%、-14.9%和-13.9%,说明北京城区出现污染物浓度的周循环变化特征和日变化特征与人类活动密切相关.

Holiday effects on PM2.5 and other major pollutants in Beijing

Continuous observations of six types of pollutants (PM_2.5, NO, NO₂, O₃, CO and SO₂) were conducted at Baolian station in Beijing from 2009 to 2012. Weekly cycle of these pollutants and their concentration differences between the two special annual public holidays (Chinese New Year and National Day) and non-holidays were examined. Weekend and holiday effects were significant for all pollutants, with higher O₃ concentration over the weekend and holidays while higher concentrations for all other pollutants during the weekdays and non-holidays). PM_2.5, CO and SO₂ during the Chinese New Year holiday are higher, and the abnormal changes in the concentrations are related to the intensive activities such as releasing fireworks and setting off firecrackers to celebrate the Chinese New Year. There is a strong diurnal variation in the pollutants' concentrations, and the peak period corresponds with an increase of human activities. The most pronounced differences for NO, NO₂ and CO between weekdays and weekend occur at 8 am local time with -19.8%, -14.9% and -13.9% respectively. This suggests that the weekly cycle and diurnal pollutants in Beijing urban area are largely related to human lifestyles and human-related activities.