乌鲁木齐大气颗粒物的时空分布规律

Temporal and spatial distribution of atmospheric particulates over Urumqi during the latest 3 years

依据峡口城市乌鲁木齐市2013—2016年6个环境监测站逐时的6类污染物数据,分析大气污染物的时空分布规律。总体来看,乌鲁木齐市以颗粒物污染为主,即PM_(10)、PM_(2.5)污染严重。从季节上来看,乌鲁木齐污染物浓度大多冬季高、夏季低,春秋季次之。春、夏、秋、冬PM_(2.5)的浓度依次为59.8、40.5、67.8、139.6μg·m^(-3),而PM_(10)则是148.6、119.7、146.4、209.4μg·m^(-3),粗细粒子浓度在春秋季的细微变化凸显在春季沙尘天气的影响。从日变化方面来看,污染物多呈现为双峰型结构。PM_(10)、PM_(2.5)春夏秋3个季节都是在子夜1:00时浓度最高,9:00～10:00时次之,但是冬季日最高值则出现在17:00时左右,次峰值出现在21:00～22:00时。从空间分布来看,颗粒物浓度总体上是中心城区低、四周高的分布格局;从PM_(2.5)浓度占PM_(10)浓度比重分析来看,冬季比重最高,达70%,以城区及城北最为明显,达73%,日变化分布则主要集中在下午至夜间,且冬季比重达71%。

The project of changing fuel from coal to natural gas in Urumqi,Xinjiang,China was launched in 2013.Since then the forming mechanism of the pollutants and the relationship between the meteorological condition and the pollutants concentration have been changed.Aimed to understand that change,this study analyzed the temporal and spatial distribution of atmospheric particulates over Urumqi using air pollutant concentration data of 6 kinds of pollutants collected from 6 environmental monitoring stations during the period from 2013 to 2016.The results showed that the main pollution of Urumqi was particulate matter （PM）,including PM10 and PM2.5.The average concentrations of PM10 and PM2.5 were 150 μg·m-3 and 75.5 μg·m-3 respectively and 32.9% of the time throughout a year had PM10 concentration above the average and 28.5% for PM2.5.Most of the pollutants concentration showed a higher value in winter,a lower value in summer,and medium value in spring and autumn.For example,the PM2.5 concentrations were 59.8,40.5,67.8, and 139.6 μg·m-3 in spring,in summer,in autumn and in winter respectively while correspondingly the PM10 concentrations were 148.6,119.7,146.4,209.4 μg·m-3 respectively.The subtle change on the concentrations of particulates with different thicknesses between spring and autumn was mainly due to the sand and dust weather in spring.From a daily distribution point of view,it formed a double-peak distribution about the pollutants and the higher peak appeared at 1：00 AM and the next peak around 9：00-10：00 AM in sprint,summer and autumn for both PM10 and PM2.5. But in winter,the higher peak appeared at about 17：00 PM and the next peak at about 21：00-22：00 PM.From the view of spatial distribution,the concentration in general showed a distribution pattern with lower values in the center of the city and higher values in other places around the city. From the components of the particulates perspective,PM2.5 accounted for 70% on average with the higher proportion of 73% in the downtown and northern part of the city in winter.