乌鲁木齐市冬季采暖期对流层NO2柱浓度变化特征

Characteristics of Atmospheric NO_2 Vertical Column Densities in Heating Period of Urumqi

NO_2是大气对流层的一种痕量气体,也是城市空气污染的重要监测指标,影响着生态环境和人体健康。特殊的地形及不利于污染物扩散的天气条件,使得乌鲁木齐市冬季采暖期大气污染最为严重。2014—2016年采暖期(11月至翌年3月)在乌鲁木齐市城中心(市区)和城北部(工业园区)利用地基多轴差分吸收光谱仪(MAX-DOAS)对大气NO_2进行了监测,探讨NO_2柱浓度的变化特征及其污染来源。结果表明,(1)与2014—2015年采暖期相比,2015—2016年采暖期市区监测站点NO_2柱浓度下降了6.8%,工业园区监测站点上升了28.5%;NO_2柱浓度月均值表现出12月最大,3月最小,浓度范围是3.905×10^(15)~20.034×10^(15) molec·cm^(-2);两监测站NO_2柱浓度日变化明显,市区晚上偏高;工业园区早晚偏高,且晚大于早。(2)64%~71%的NO_2柱浓度的逐日变化由气象要素决定,其中平均风速对NO_2柱浓度的影响最显著;市区NO_2的污染源主要分布在东、东北和西南方向,正南北方向的风对NO_2有扩散作用;工业园区NO_2的污染源来自西北和东南方向,南风及偏东风对NO_2具有扩散作用。(3)乌鲁木齐市"煤改气"工程初见成效,而市周边工业园区及机动车尾气排放仍是大气污染治理的重点。

NO2 was a trace gas in the atmosphere, also was the important monitoring indexes in the air pollution of urban, hadinfluence on ecological environment and human health. Due to special terrain and bad weather, the air pollution of Urumqi was themost serious. The characteristics of NO2 vertical column densities (VCD) during the heating period of 2014—2016 (November toMarch) were analyzed based on the NO2 monitoring data released on the multi axis DOAS at urban area and industrial area sites ofUrumqi, also correlation between NO2 and meteorological factors. The analytical results showed that, (1) Compared with the heatingperiod of 2014—2015, the NO2 VCD of urban area sate during heating period of 2015—2016 were decreased by 6.8%, but theindustrial area site were increased by 28.5%; with its monthly mean being maximum in December and minimum in March, the rangeof NO2 VCD were 3.905×1015~20.034×1015 molec·cm-2; the diurnal variation of NO2 VCD was obvious in both two sites. (2) 64% to71% of the daily change of concentration of NO2 VCD was determined by the meteorological elements, especially average windspeed; the main sources of NO2 were from the east, the northeast and southwest in urban area, north and south direction of the windhad spread effect to NO2; NO2 pollution from the industrial area's northwest and southeast, southerly and easterly of NO2 can bediffused. (3) “the changing fuel coal to natural gas” project in Urumqi had the success, and industrial area and motor vehicleemissions continue to be the focus of atmospheric pollution control.