兰州市SO2时空动态分布特征及其与城市生态系统的关系

强化城市大气污染物多尺度监测手段,辨识污染物时空演变规律及其与城市生态系统各要素间的相互关系,可为城市大气环境质量综合管控提供科学依据。利用OMI、EOS/MODIS卫星影像及其他统计类数据,在分析了兰州市2006—2016年对流层SO_2柱浓度的时空分布特征基础上,进一步探讨了NDVI、工业总产值、汽车保有量等城市自然经济社会生态要素的结构变化与SO_2浓度变化的关系。结果表明:1)兰州市对流层SO_2空间分布不均,呈现出以河谷低海拔区域分布为中心,向西北、东南山地两侧递减的"倒U"形格局;2)近10年内,兰州市大气SO_2柱浓度值在0.033—0.25(多布森单位)之间,总体呈下降趋势,年均降幅为14%,降速为0.02(多布森单位)/a;3)兰州市大气SO_2柱浓度变化特征与城市工业生产和交通因素关系密切,又受地形、季节风向等气象气候条件制约;4)兰州市NDVI指数与大气SO_2柱浓度值相关性明显,兰州市植被覆盖度较低,植被指数为0.09—0.66,对SO_2净化能力有限。综合以上结果,本研究认为,通过调控城市社会、经济、自然生态系统结构,并适当采用基因工程等科学技术来增加地表植被覆盖量,是下一步兰州市大气环境质量管理的重要举措之一。

Spatial and temporal dynamic distribution characteristics of SO2 in Lanzhou City and its relation with urban ecosystem

Strengthen the methods of multi-scale monitoring for urban air pollutants, identified the temporal and spatial development of pollutants and their relationships with the elements of urban ecosystem can provide a scientific basis for comprehensive management and control of urban air quality. This research analyzed the temporal and spatial distribution characteristics of SO₂ column concentration in the troposphere of Lanzhou City from 2006 to 2016, based on OMI, EOS/MODIS satellite images, and other statistical data. The paper further discussed the relationship between the SO₂ concentration and urban structural changes of natural, economic, and social elements, such as NDVI, industrial production, car parc. The results showed that 1) the spatial distribution of SO₂ presented an inhomogeneous characteristic in the troposphere in Lanzhou city, which showed an inverted U-shaped pattern with the low elevation of the valley as the center and decreased on both sides of the northwest and southeast mountain areas. 2) In the past 10 years, the concentration of SO₂ column in Lanzhou was between 0.033-0.25 Dobson unit. It showed the downward trend with an average annual decline of 14%, and with the declining rate of 0.02 Dobson unit/a. 3) The characteristics of atmospheric SO₂ column concentration change of Lanzhou city were closely related to urban industrial production and traffic factors, and also restricted by the meteorological and climatic conditions such as topography and seasonal wind direction. 4) The NDVI index of Lanzhou city was significantly correlated with the concentration of atmospheric SO₂ column. Lanzhou city had a low vegetation coverage, with the vegetation index of 0.09-0.66. It had a limited ability to purify SO₂. Based on the above results, we consider that it is one of the important measures for Lanzhou''s atmospheric environmental quality management to increase the surface vegetation coverage by adjusting the structure of urban social, economic, and natural ecosystems, and using appropriate science and technology such as genetic engineering.