Abstract:

Air pollution, represented by PM_2.5 and PM₁₀, has a huge impact on the lives of urban residents. The street canyon is an important part of a city and one of the main places where urban residents live. This paper selects three typical functional street canyons in Hefei to monitor the changes in PM_2.5 and PM₁₀ mass concentrations, and uses correlation analyses and regression analyses to study the differences between PM_2.5 and PM₁₀ in different functional street canyons and their influencing factors. The air quality evaluation model is used to evaluate the air quality. The results show that: (1) There is a high correlation between the PM_2.5 and PM₁₀ in street canyons, with the peaks appearing at 08:00-09:00, and the troughs mostly appearing at 14:00-15:00. The peak of PM_2.5 is 61.22-73.71 μg∙m^-3, and the trough is 32.73-33.59 μg∙m^-3; the peak of PM₁₀ is 67.65-85.19 μg∙m^-3, and the trough is 37.35-39.81 μg∙m^-3. Both are near the limit of the primary standard. (2) Hefei's street canyons for office and commercial use both show an obvious declining bimodal peak form, and the residential street canyons show a steady bimodal peak form. The concentration of PM_2.5 and PM₁₀ in street canyons shows the following pattern: office type>commercial type>residential type. The peaks of PM_2.5 and PM₁₀ mass concentrations in street canyons are mostly in sunken squares and secondary arterial roads, and the trough values are mostly near the green belts of the main arterial roads and the intersections of the main and secondary arterial roads. (3) In summer, the PM_2.5 mass concentration in the street canyons of Hefei City has a significant positive correlation with the PM₁₀ mass concentration and the relative humidity, and a significant negative correlation with the air temperature. (4) Based on the AQI index, the evaluation results of different functional streets canyons in Hefei during summer show that the air quality levels are mainly excellent, and the air quality levels are mostly distributed in the first and second grades. This study compares the pollutant concentrations of different functional street canyons in Hefei to provide basic parameters for the evaluation of street canyon features.

Key words: street canyon, functional zoning, air pollution, air quality evaluation, PM_2.5, PM₁₀

摘要：

以PM_2.5和PM₁₀为代表的空气污染对城市居民的生活产生了巨大的影响。街道峡谷是城市的重要构成部分,是城市居民生活的主要场所之一。选择合肥市3种典型功能的街道峡谷,监测PM_2.5和PM₁₀质量浓度变化,采用相关分析和回归分析等方法,研究不同功能街道峡谷PM_2.5和PM₁₀的差异及其影响因素,并采用空气质量评价模型对其空气质量进行评价。结果表明,（1）街道峡谷PM_2.5和PM₁₀质量浓度之间具有较高的相关性,波峰出现在08:00—09:00,波谷多出现在14:00—15:00。PM_2.5质量浓度波峰为61.22—73.71 μg∙m^-3,波谷为32.73—33.59 μg∙m^-3;PM₁₀质量浓度波峰为67.65—85.19 μg∙m^-3,波谷为37.35—39.81 μg∙m^-3,均位于一级标准极限值上下。（2）合肥市办公型街道峡谷与商业型街道峡谷日变化呈明显的下降型双峰形式,居住型街道峡谷呈平稳型双峰形式。街道峡谷PM_2.5和PM₁₀质量浓度：办公型>商业型>居住型。街道峡谷内PM_2.5和PM₁₀质量浓度峰值多在下沉广场和次干道,低谷值多在主干道绿化带旁和主次干道交叉口。（3）夏季,合肥市街道峡谷PM_2.5质量浓度与PM₁₀质量浓度、相对湿度呈现显著的正相关,与空气温度呈现显著的负相关。（4）运用AQI对合肥市夏季不同功能街道峡谷进行评价,其空气质量级别以优良为主,空气质量级别多分布在一级和二级。该研究对合肥市不同功能街道峡谷的污染物浓度进行对照,为街道峡谷特征功能评估提供了基本参数。

关键词: 街道峡谷, 功能分区, 空气污染, 空气质量评价, PM_2.5, PM₁₀