河南省北部区域霾污染过程中城市和农村点位PM_(2.5)组分差异

Differences in PM_(2.5) Components Between Urban and Rural Sites During Heavy Haze Event in Northern Henan Province

近年来,我国京津冀及其周边地区暴发了多次霾污染过程,受观测仪器等因素的限制,尚未有对河南省北部城市和农村霾污染的对比研究.利用一系列在线高时间分辨率的观测仪器在河南省2个城市点位和3个农村点位对一次区域重污染过程(2018年1月12~25日)进行综合观测.结果表明SO_(4)^(2-)、 NO_(3)^(-)和NH_(4)^(+)(SNA)是此次区域污染过程中5个点位PM_(2.5)中占比最高的组分,位于53%~63%之间,以NO_(3)^(-)为主24%~32%,其次为SO_(4)^(2-)(13%~17%).相较于城市点位,农村点位PM_(2.5)中有机物的占比更高,尤其是夜间.随着污染的加重,SNA的占比上升,重污染时段可达67%.此外,当区域受南部气团的传输影响时,5个点位PM_(2.5)中NO_(3)^(-)的占比增大;受北和东北部气团的传输影响时,PM_(2.5)中SO_(4)^(2-)和有机物的占比增大.硝酸铵是导致霾过程中大气能见度下降最主要组分,并且硝酸铵和硫酸铵对城市点位的影响高于农村点位.综上,城市和农村点位PM_(2.5)组分差异显著,城市地区需继续加强对气态前体物的削减,农村地区需同时重视碳质气溶胶排放源的管控.

In recent years, the Beijing-Tianjin-Hebei region and its surrounding areas have experienced multiple haze pollution processes. Owing to the limitation of observational instruments, there has not been a comparative study of haze pollution between urban and rural areas in northern Henan province. A series of high-time-resolution instruments were used during a regional heavy pollution process(January 12-25, 2018) at two urban sites and three rural sites. The results showed that SO_(4)^(2-), NO_(3)^(-), and NH_(4)^(+)(SNA) were the components with the highest proportion in PM_(2.5)at the five sites during the haze event with a range of 53%-63%, of which nitrate was the most important, accounting for 24%-32%, followed by sulfate, ranging from 13%-17%. Compared with urban sites, rural sites were more affected by organic matter, especially at night. With the aggravation of pollution, the proportion of SNA increased, reaching 67% during periods of heavy pollution. When the area was affected by the air mass transported from the south, the proportion of NO_(3)^(-)in PM_(2.5)increased, and when the area was affected by the air transport in the north, the proportions of SO_(4)^(2-)and organic matter increased. Ammonium nitrate was the most important component that led to the decrease in atmospheric visibility during the haze process. Moreover, the contributions of ammonium nitrate and ammonium sulfate at the urban sites were higher than those at the rural sites. To summarize, there were significant differences in PM_(2.5)components between the urban and rural sites. Urban areas need to continue to strengthen the reduction in gaseous precursors, and rural areas need to pay attention to the sources of carbonaceous aerosol.