城市扩展下大气污染物浓度的空间格局变化趋势研究——以乌鲁木齐市为例

Effects of the urban expansion on the spatially varying trends of distribution in air pollutants concentration:a case study of Urumqi

城市环境污染是由于人类的生产和生活活动造成,而不断的城市扩展势必导致环境污染物浓度的空间变化。乌鲁木齐市作为中国西部的内陆城市,由于特殊的地理位置和能源结构,在发展经济的同时也造成了严重的大气环境污染,也给人们的生产生活带来了严重的影响。为了治理污染当地政府采取了一系列措施。分析了2004—2009年城市3个不同区域(市南区、市中区和市北区)大气环境质量监测点位的数据,研究了在城市不断扩展的前提下,污染物浓度在空间上的迁徙变化趋势。结果表明,PM10、SO2和NO2污染最严重的时段均出现在冬季采暖期(12月至来年1月),主要是因为采暖消耗大量原煤和高逆温频率所致。其峰值分别达到0.379、0.510、0.120 mg.m-3。随着城市空间结构的不断北扩,PM10和SO2的浓度呈现出向北迁徙的趋势,原本污染最严重的市南区浓度逐步下降,而市北区呈现出不断增加的态势。NO2浓度则表现出不断南迁的趋势,即原本NO2浓度高的市北区变化不大,而市南区和市中区则呈现出快速增加的态势。说明大气环境中的污染物浓度随着城市空间结构的调整和人类活动频率的不断增加,正发生着空间上迁徙变化。由于污染排放源的差异性,导致大气污染物浓度在空间上的不同。通过分析得出,乌鲁木齐市的大气环境污染主要是"煤烟型"污染,随着产业的空间分布和城市的扩展,污染物浓度在空间上呈现出了不同的迁徙变化特征,是今后城市发展和环境治理值得关注的问题。

Human activities have resulted in increasing urban environmental pollution in cities, and the continuous urban expansion will inevitably lead to the spatial variation of the concentration of environmental pollutants. Urumqi is an inland city of northwest China. Its special geographical location, energy structure and economic development have caused serious air pollution and people＇s production and living have been seriously affected. Therefore, in order to control pollution, local government has taken a series of measures. In the present study, we analyzed the pollutants concentration data collected from three different regions （the south, middle and north of the city） of Urumqi atmospheric environmental quality monitoring station during 2004--2009. Moreover, the moving trends of the concentration of pollutants in space with the expansion of the city were studied. The present data indicated that the maximum PM10, SO2 and NO2 reached 0.379, 0.510, 0.120 mg·m^-3 respectively from December to January in winter. It was due to a large number of coal consumption for heating and the high occurrence frequency of temperature inversion layers. With the rapid spatial expansion of urban area in the north, the PM10 and SO2 concentrations showed a trend of northward migration. In addition, the pollutants concentrations in the most polluted south area of city have gradually declined, while the pollutants concentrations in north of city have increased during the city＇s expansion. The NO2 concentrations showed a southward migration trends, namely, the NO2 concentration changed a little in the north area of city, while it increased rapidly in south and middle areas. These results showed that the pollutants concentration is experiencing a migration change in the space due to the rapid expansion of city and high dense human activities. Differences pollution emission sources lead to the variation of the concentration of air pollutants in the space. Based on these findings, we conclude that atmospheric pollution is a type of ＂coal smoke＂ pollution in Urumqi and with the spatial distribution of industries and urban expansion, the concentration of pollutants in space showed different characteristics of migration.