奎屯市-独山子区-乌苏市区域大气对流层NO2柱浓度时空变化分析

为研究以石化工业为主的奎屯市-独山子区-乌苏市（简称“奎-独-乌”）区域大气对流层NO₂柱浓度的时空变化，基于地基多轴差分吸收光谱仪（MAX-DOAS）于2018年2月—2019年7月在各城市城区中心进行固定监测（09:00—20:00），以及在环奎-独-乌区域进行车载移动监测（10:00—15:00），结合地形地貌、气象、工业分布和人为排放量等因素，反演分析该区域对流层NO₂柱浓度的时空变化规律.结果表明:①奎-独-乌区域对流层NO₂柱浓度日变化呈早晚高、中午低，冬季高、夏季低的特点，对流层NO₂柱浓度季节性变化呈冬季（11.8×1015 molec/cm2）>秋季（9.46×1015 molec/cm2）>春季（7.46×1015 molec/cm2）>夏季（4.33×1015 molec/cm2）的特征.奎-独-乌区域对流层NO₂柱浓度最高值均出现在冬季（1月），呈独山子区（22.23×1015 molec/cm2）>奎屯市（21.30×1015 molec/cm2）>乌苏市（18.34×1015 molec/cm2）的特征.②奎-独-乌区域大气对流层NO₂柱浓度存在空间集聚现象，且区域内部差异显著.不同季节高值主要出现在区域内交通交错区（奎屯立交桥、独山子立交桥）和工业集中分布区，最低值均出现在奎-独-乌区域西南部的乌苏市，且位于主导西风通道的上风向.③结合后向轨迹分析发现，奎-独-乌区域气流来源中冬季气流运动在水平方向和垂直方向上均不利于污染物扩散，夏季西北风向导致下风向路段NO₂浓度相对较高，该区域大气NO₂污染物以本地输送为主，且在城际间存在污染物的传输与积累.④奎-独-乌区域的能源结构以煤炭为主，其固定源排放以工厂和电力部门为主，而乌苏市交通移动源所产生的NO₂排放总量远高于奎屯市和独山子区.该区域冬季燃煤6个月，低风速（1.5~3.0 m/s）频率持续时间较长，加之独特的山盆结构形成的“山谷风”，有较厚的逆温层，不利于污染物远距离扩散.研究显示，能源工业结构背景下形成的奎-独-乌区域环境有利于大气污染物的聚集和积累，其污染源以本地污染为主. 

Spatial and Temporal Variation of Atmospheric Tropospheric NO2 Column Concentration in Kuitun City,Dushanzi District and Wusu City

The spatial and temporal variation of atmospheric tropospheric NO₂ column concentration in Kuitun City, Dushanzi District, and Wusu City (hereafter Kui-Du-Wu Region) was studied. The region is dominated by the petrochemical industry. Combined with topography, meteorology, industrial distribution and anthropogenic emissions, a ground-based multi-axis differential absorption spectrometer (MAX-DOAS) were used to invert the NO₂ column concentration at fixed points in the center of each city (09:00-20:00) and vehicle-mounted mobile monitoring (10:00-15:00) in the Kui-Du-Wu Region from February 2018 to July 2019. The results show that: (1) The daily variation of tropospheric NO₂ column concentration in Kui-Du-Wu Region is higher in the morning and evening than at noon, and is higher in winter than in summer. The detailed NO₂ column concentration is winter (11.8×1015 molec/cm2) > autumn (9.46×1015 molec/cm2) > spring (7.46×1015 molec/cm2) > summer (4.33×1015 molec/cm2). The highest values in the three sites all appear in winter (January), which is Dushanzi District (22.23×1015 molec/cm2) > Kuitun City (21.30×1015 molec/cm2) > Wusu City (18.34×1015 molec/cm2). (2) There is a spatial accumulation of NO₂ in the troposphere in Kui-Du-Wu Region, and there are significant differences within the region. The high values in different seasons mainly appear at regional traffic intersections (Kuitun overpass, Dushanzi overpass) and industrial concentration areas. The lowest values all occurred in Wusu City, the southwest of the Kui-Du-Wu Region, which is located in the upwind direction of the dominant westerly channel. (3) Combined with the analysis of the backward trajectory of the air mass, it is found that the movement of air mass in winter is not conducive to diffusion in both the horizontal and vertical directions in the Kui-Du-Wu Region. The northwesterly wind in summer leads to relatively high NO₂ concentration in the downwind section. The atmospheric NO₂ pollutants in this area are mainly transported locally, and there are transmission and accumulation of pollutants between cities. (4) The energy structure of Kui-Du-Wu Region is dominated by coal, and its stationary source emissions are dominated by factories and power sectors, while the atmosphere produced by the mobile sources of transportation in Wusu City. The total pollutant NO₂ emissions are much higher than Kuitun City and Dushanzi District, where coal is burned for 6 months in winter, and the low wind frequency (1.5-3.0 m/s) lasts for a long time. In addition, the 'valley wind' formed by the unique mountain basin structure has a deep temperature inversion layer, which is not conducive to the long-distance diffusion of pollutants. This research shows that the Kui-Du-Wu regional environment formed under the background of the energy industry structure is conducive to atmospheric pollutants. The pollution source is mainly local pollution.