摘要
大气细颗粒物PM2.5是导致城市能见度降低的重要原因之一,研究低层大气细颗粒物的垂直分布特征,利于了解边界层内污染物的大气物理化学反应机制,能为大气污染综合治理决策提供新的科学数据。2006年8月16日—2007年8月31日期间以天津市255m气象塔为观测平台,分别在40m、120m和220m3个不同高度进行大气污染物PM2.5质量浓度和气象要素的同步观测。对观测资料的分析表明:PM2.5质量浓度季节变化规律非常明显,冬季最高,春季最低。PM2.5日变化特征非常明显,呈明显的双峰变化规律:冬季峰值最大、春季最小。边界层内PM2.5质量浓度在各个高度存在明显差异,受逆温层影响,四个季节的早晨第一个峰值出现时间随高度增加均存在滞后现象,PM2.5从地面扩散到220m大约需要2h。各个观测高度PM2.5质量浓度随风向变化不大,得到天津市细粒子主要是由本地源生成的结论。
The pollution caused by atmospheric particulate PM2.5 is one of the important factors affecting urban visibility, research on the vertical distributive characters of PM2.5 at the ground layer is benefit for the understanding the formation mechanism of the primary pollutants, which will provide a new scientific basis for the comprehensive pollution control. Experiments were carried out froln 16, Aug of 2006 to 31,Aug of 2007 on the meteorological tower of 255 m height in Tianjin. The observation of PM2.5 mass concentration with the meteorological elements at three levels of 40 m, 120 m and 220 m areanalyzed. The lnajor results are showed as follows： Firstly, seasonal variations of PM2.5 are significant, which is the greatest in winter, and the smallest in spring. Secondly, daily variation of PM2.5 at each level is also significant, with two obvious peaks observed. The winter peak is higher in magnitude than in spring. Thirdly, the PM2.5 concentration at each level in the boundary layer is markedly different. Affected by the nocturnal inversion layer, the time of first peak occurring in the morning in four seasons have an obvious lag. It needs about 2 hours for the PM2.5＇s expanding from the surface to 220 in height. The PM2.5 mass concentration at different height varies little with wind direction, So, a conclusion is drawn the particulate pollution in Tianjin is mainly caused by local source emissions.
出处
《生态环境》
CSCD
北大核心
2008年第3期975-979,共5页
Ecology and Environmnet
基金
国家科技部公益基金项目(2005D1B3J105)
天津市科委项目(07ZCGYSF03200)
关键词
PM2.5
近地层
垂直分布
夜间混合层高度
PM2.5
ground layer of the atmospheric
vertical distribution
height of the nocturnal mixing layer
