夏末秋初北京市区与背景区大气污染物的对比分析

在北京市区和背景区--河北兴隆县选点,对比两地大气污染物浓度变化及污染状况.结果表明:除O3外,北京市区主要大气污染物浓度均高于背景区,其ρ(PM10),ψ(NOx)和ψ(SO2)的平均值分别是背景区的1.6,3.1和4.0倍,而背景区ψ(O3)平均值则是北京市区的2.2倍;与国家二级标准限值比较,夏末秋初基本上不存在SO2和NOx污染,大气污染物中超标最严重的是O3,北京市区与背景区的超标天数分别是46.9%和65.5%,其次是PM10,北京市区超标天数达到25%,背景区则全部达标;北京市区与背景区的大气污染物日变化特征明显不同,其中北京市区的日变化主要受人为活动影响,表现出典型的城市特征,而背景区日变化受人为活动影响小.

Comparison of the Characteristics of Ambient Pollutants in Urban and Background Region in Beijing during August and September

Two sites were selected to observe the concentration of air pollutants in the atmosphere. One is in Beijing urban area and the other, as background region, is at Xinglong County of Hebei Province. The results showed that the concentrations of major air pollutants, except 03, in urban area were higher than those in background region. The concentrations of PM10, NOx and SO2 in urban area were 1.6, 3.1 and 4.0 times of those in background region, respectively. However, the concentration of O3 in background region was 2.2 times of it in urban area. Compared with the second-grade national air quality standard, the concentrations of SO2 and NO2 in late summer and early autumn are very low, and O3 pollution was the worst for all pollutants being observed, followed by PM10. During the observation, the number of days of O3 concentration exceeding the second-grade standard limit was 46.9 % and 65.5 % respectively in urban and background atmosphere, while the number of days of PM10 mass concentration exceeding the second-grade standard limit was 25 % in urban and none in background atmosphere. The characteristics of diurnal variation of major air pollutants in urban area were obviously different from that in background region. Diurnal variation of major air pollutants in urban area was mainly affected by human activity, which has small effects on diurnal variation of air pollutants in background region.