乌鲁木齐市区与南郊山区颗粒物污染特征对比分析

Comparative analysis of particulate pollution characteristics between Urumqi urban area and southern mountainous area

利用2017年10月~2018年8月的PM_(10)、PM_(2.5)、PM_(1)质量浓度数据以及NCEP全球再分析气象资料,分析乌鲁木齐市区和南郊山区颗粒物浓度变化特征,结合HYSPLIT后向轨迹模型、潜在源贡献因子分析(PSCF)以及浓度权重轨迹分析(CWT)分析市区颗粒物潜在源区.研究结果表明:①市区PM_(2.5)的超标天数为26d,南郊山区无PM_(2.5)超标,市区PM_(10)的超标天数是南郊山区的3.5倍,市区日均值及月均值质量浓度是南郊山区的2~7倍,市区呈现冬高夏低的季节特征,南郊山区春季最高;②乌鲁木齐市区PM_(10)日变化存在3个峰值,PM_(2.5)、PM_(1)为双峰型分布,南郊山区均呈双峰分布;并存在季节性周末效应;③长短两支聚类气流轨迹对乌鲁木齐市区颗粒物浓度影响较大,春夏气流来自中亚,秋冬来源于北疆周边地区;④颗粒物潜在源区分布季节特征显著,高值区主要为昌吉、巴州、吐鲁番等周边地区,西北部中亚地区也是颗粒物重要来源区域之一.

Based on the observational data of PM_(10),PM_(2.5) and PM_(1) concentrations from October 2017 to August 2018 as well as NCEP reanalysis data of meteorology,this paper analyzed the variations of particulate concentrations in the urban area and the mountainous area in the southern suburbs of Urumqi,combined with HYSPLIT backward trajectory modelling,potential source contribution factor analysis(PSCF)and concentration weight trajectory analysis(CWT)to analyze the potential sources of particulate matter in urban areas.The results show that:(1)In the urban area,PM_(2.5) exceeded the standard for 26 days,while in the southern suburbs,no PM_(2.5) exceeded the standard,and the number of days exceeding the standard for PM_(10) in the urban area was 3.5 times higher than that in the southern suburbs,The daily and monthly mean PM_(10) concentrations in urban area is 2~7 times that in the southern suburban area.The urban area presented the seasonal characteristics of high in winter and low in summer,while the southern suburban area observed the highest in spring.(2)The diurnal variation of PM_(10) in Urumqi has three peak values,PM_(2.5) and PM_(1) have bimodal distribution in the urban area,and the southern mountainous areas presented the bimodal distribution in diurnal PM_(10) change.There is seasonal weekend effect.(3)The trajectory of the long and short clusters of air flow has a great influence on the concentrations of particulate matter in Urumqi.Air flows in spring and summer is traced from Central Asia,and air flow in autumn and winter from the surrounding areas of northern Xinjiang.(4)The seasonal variations of potential sources of particulate matter are significant,and the high values are mainly in Changji,Bazhou,Turpan and other surrounding areas.The central Asian area in northwest China is also one of the important sources of particulate matter.