珠江三角洲土地利用变化对特征大气污染物扩散的影响

Effects of land use change on specific air pollutants dispersion in the Pearl River Delta Region

在珠江三角洲两种下垫面条件下,应用CALPUFF大气污染扩散模式,对特征污染物SO2、SO42-的扩散进行数值模拟,探讨大规模土地利用变化,尤其是城镇建设用地增加,对珠江三角洲地区大气污染物扩散的影响,并通过对4个典型区污染物月均质量浓度变化特征分析,揭示土地利用变化对不同地区的污染物分布的影响机制。模拟结果表明:土地利用变化,尤其是城镇建设用地增加,不利于污染物扩散,污染源下风方向地区受影响较大,污染物质量浓度明显升高,SO2和SO42-年均质量浓度分别增加14.07%和3.31%;受影响范围、变化幅度与污染源排污强度呈正相关,变化幅度亦与污染源距离远近呈负相关。土地利用变化后,尤其是城镇建设用地增加,四个典型区SO2月均质量浓度都表现为升高趋势,且冬季SO2质量浓度升高幅度最大,夏季升高幅度最小,临近污染源密集区的两个典型区SO2月均质量浓度分别增加33.6%和26.3%。土地利用变化不仅改变局地的污染扩散,也会对区域的污染扩散有一定影响,尤其对污染源分布密集区的大气污染物扩散影响强度最大。因此,建议人类在城市化建设过程中尽可能保留自然斑块,消除人工下垫面对污染物扩散的负面影响。

In the Pearl River Delta Region, based on two underlying surfaces, this study applied CALPUFF atmospheric dispersion model to simulate dispersion of sulfur dioxide （SO2） and secondary sulfate （SO42-）, to investigate the impact of land use change （especially the increase of areas of civil land use） on the distribution and dispersion of specific air pollutants. In addition, this paper analyzed the changes of pollutants monthly concentration in the four special areas which is in the study region, to reveal the impact of land use change on different areas. The results showed that land use change （especially the increase of areas of civil land use） went against the dispersion of pollutants. The impact to leeward of pollution sources was larger, where pollutants concentration increased observably. The annual concentration of SO2 and SO42-increased by 14.07%and 3.31%respectively in leeward of pollution sources. Affected scope was positively related to pollution emission intensity, which mean affected areas in leeward of pollution sources was larger while pollutants emission intensity was larger. Change range was related to the pollution emission intensity and distances from the pollution sources. After the change of land use, especially the increase of areas of civil land use, SO2 monthly concentration showed a higher trend in four typical areas. In winter, increase range of SO2 concentration is largest. Beyond that, SO2 monthly concentration increased by 33.6%and 26.3%respectively in two typical areas that were near the pollution sources. Land use change not only effected local pollutants dispersion, but the pollutants dispersion in the region, particularly to the areas near to pollution sources. So we should retain the nature as far as possible in the process of urbanization, to eliminate the negative impacts of increased artificial building on pollutants dispersion.