汾渭平原PM_(2.5)空间分布的地形效应

Orographic Influences on the Spatial Distribution of PM_(2.5) on the Fen-Wei Plain

地形不仅通过制约人口和产业布局作用于污染物排放的空间分布,而且对PM_(2.5)的形成、传输、累积、扩散和沉降有深刻影响,是PM_(2.5)空间分布的重要影响因素,盆地地区表现尤为显著.本文基于栅格数据,利用均值变点法、回归分析、地理探测器和双变量空间自相关分析等方法,从自然和人为因素两方面选取指标,探讨汾渭平原PM_(2.5)浓度分布的地形效应及影响机制.结果表明:(1)汾渭平原地形起伏度总体呈中部低、四周高分布,与海拔分布基本一致.(2)PM_(2.5)分布格局与地形起伏度相反,总体呈中部高、四周低,且随地形起伏度的升高呈对数关系递减.(3)地理探测器分析结果显示,汾渭平原PM_(2.5)分布格局主要由人口、GDP和能源消费等人为因素决定,气象和植被等自然因素对PM_(2.5)分布也有一定的调节作用.(4)地形对人为和自然因素均有显著影响,随着地形起伏度的增加,人口、GDP和能源消费而呈幂函数关系递减,气温呈线性递减,降水量、相对湿度和风速呈线性递增,植被指数呈对数关系递增.

Topography not only has an effect on the spatial distribution of pollutants by restricting populations and industrial activities,but also affects the formation,transmission,accumulation,diffusion,and sedimentation of PM_(2.5).Topography is,therefore,an essential variable for understanding the spatial distribution of PM_(2.5),especially in basin areas.Based on gridded data and both natural and human indexes,this paper examines orographic effects on the distribution of PM_(2.5)on the Fen-Wei Plain based on the change point method,regression,the geographical detector method,and bivariate spatial autocorrelation.The results indicate that:(1)The relief amplitude of the plain is generally lower in its central part than at its edge,which is similar to the attitudinal distribution in this region;(2)The distribution of PM_(2.5)is negatively related to relief amplitude,with high concentrations in central area and lower concentrations at the edge;(3)Based on the geographical detector analysis,PM_(2.5)patterns in this region are shaped by human factors including population,gross domestic product(GDP),and energy consumption,as well as natural factors including meteorological conditions and vegetation;and(4)Topography has a significant effect on both human and natural factors;an increase of relief amplitude is associated with a decrease in population,GDP,and energy consumption based on power function.Accordingly,temperature goes down linearly;precipitation,relative moisture,and wind speed increase linearly;and the vegetation index increases based on a logarithmic function.