2001—2007年兰州市主要大气污染物污染特征分析

Characteristics of Main Air Pollution in Lanzhou During 2001-2007

以兰州市2001-2007年空气污染指数资料为基础,对每日空气污染指数(Air Pollution Index,API)、空气质量级别和PM10浓度等的年、季、月变化特征以及采暖期和非采暖期污染变化差异进行了分析。结合甘肃省地面气候资料集兰州市日观测资料,通过单因素方差分析和线性相关分析,找出不同季节对PM10浓度有显著影响的气象要素,得到不同季节与PM10浓度呈显著线性相关的气象因子。结果表明:(1)兰州市的首要污染物仍以PM10为主,其中冬季和春季污染最严重,PM10浓度在冬季12月有一主峰值,在春季3,4月份有一次峰值;(2)近年来,兰州市污染天数有减少趋势,并与兰州市烟、粉尘年排放量减小趋势一致;(3)采暖期PM10浓度有明显减小趋势,而非采暖期PM10浓度减小趋势不明显,污染日越来越集中在采暖期;(4)与PM10浓度呈显著线性相关的气象要素存在季节差异,但总体上风速、气温和湿度(或降水)是影响兰州市PM10浓度的主要气象因子,因此湿度、温度和风场条件的改变将对兰州市的大气环境产生影响。

Daily Air Pollution Index（API） were used to analyze the annual,seasonal and monthly variations of air quality in Lanzhou,Northwest China during 2001-2007.Differences in air quality during heating and non-heating seasons were also discussed.Combined with the daily surface meteorological observations from Lanzhou meteorological station,one-way ANOVA and correlation analysis were used to identify meteorological factors that have significant impact on PM10 concentration in different seasons.The main conclusions are as follows：（1） PM10 is the main pollutant in Lanzhou,there are peaks in December and March or April;（2） Number of pollution days decreases during 2001-2007,which is consistent with the decreasing trend of annual emissions of anthropogenic dust emissions;（3） Comparing to non-heating season,PM10 concentration in heating season decreases more significantly from 2001 to 2007,and more and more pollution days occur in heating season;（4） The main meteorological factors affecting PM10 concentration are different for different seasons.In general,the wind speed,temperature and relative humidity（or precipitation） are the main meteorological factors affecting PM10 concentrations in Lanzhou.