华北地区冬季和夏季大气甲醛污染特征分析

Characteristics of atmospheric formaldehyde pollution in winter and summer in North China

为探究华北地区大气甲醛的污染特征,应用自主设计的一套大气甲醛在线分析仪,于2017年冬季和2018年夏季在山东省德州市开展大气甲醛综合观测实验.结果表明,德州站冬季和夏季大气甲醛小时浓度范围分别为0.15×10^-9~9.89×10^-9和0.43×10^-9~10.42×10^-9,平均值分别为(3.04±1.70)×10^-9和(4.32±2.06)×10^-9,结合日变化特征可知,白天甲醛、过氧乙酰基硝酸酯(PAN)和臭氧(O3)具有较好的一致性,表明光化学生成是甲醛的主要来源;冬季夜间检测出的高浓度甲醛则表明一次排放也具有重要的贡献.此外,大气甲醛的浓度变化受相对湿度、光照、风速和湿沉降影响较大,并且湿沉降是大气甲醛去除的重要途径.

To analyze the variability of atmospheric formaldehyde in North China, an online formaldehyde analyzer was used in two field campaigns in winter 2017 and summer 2018 at Dezhou, Shandong Province. The hourly mixing ratios of formaldehyde range from 0.15×10^-9 to 9.89×10^-9 in wintertime and 0.43×10^-9 ~10.42×10^-9 in summertime. The average mixing ratios are (3.04±1.70)×10^-9 and (4.32±2.06)×10^-9 during winter and summer, respectively. Agreement in trends of formaldehyde, ozone and PAN in daytime indicates that photochemical production is the major source of formaldehyde;during nighttime in winter, elevated level of formaldehyde is observed, indicating the contribution from local primary emissions. The diurnal variation pattern of formaldehyde is also affected by relative humidity, radiation, wind speed and wet deposition, among which wet deposition is found to be the major sink of formaldehyde during the observation.