拉萨市环境空气中NO_2变化特征分析

Recent Atmospheric NO_2 Concentration Dynamics of Lhasa City

选取用长光程差分光谱法监测的拉萨市2000年7月—2004年6月环境空气质量监测数据,分析了NO2变化特征.结果表明:目前拉萨市ρ(NO2)在《环境空气质量标准》(GB3095-1996)一级标准之内,但呈逐渐上升趋势.拉萨市ρ(NO2)月均值呈明显的“U”字型分布规律,即1月和年末10—12月高,其他时间低;每年10月至次年1月,ρ(NO2)月均值超过年均值,月均最高值均出现在12月;每日在8:00—12:00,20:00—24:00有2个高峰值区.汽车尾气、当地居民生活中的燃烧过程是目前拉萨市NO2的主要产生源,特殊边界层气象条件影响拉萨市环境空气中ρ(NO2)的变化规律.

The variability of NO2 mass concentration in the air of Lhasa city was analyzed based on the automatically monitoring data from July 2000 to June 2004. It was shown that the NO2 mass concentration in the air of Lhasa city remained below the first degree according to the Standard of Ambient Air Quality （GB3095 - 1996）, but was increasing in recent years. The seasonal variation of NO2 mass concentration in the air was that it was higher in the winter （October to January） than in the other months, the highest NO2 mass concentration emerged in December, and the monthly average of NO2 mass concentration from October to the next January exceeded the year＇ s mean. The monthly average NO2 mass concentration showed a typical ＂U＂ shape. And daily variation showed two peaks of NO2 mass concentration in the time period of from 8：00 to 12：00 and from 20：00 to 24：00. The car emission and fuel burning in daily life were the main sources of NO2 around the Lhasa city at present in terms of human devotion, and the special weather condition in the aerosphere was another factor that affected the variability of NO2 mass concentration in the city.