The influence of plant morphological structure characteristics on PM2.5 retention of leaves under different wind speeds
Exploring the relationships between plant morphological structures and PM 2.5 (particulate matter < 2.5 µm in diameter) retention on leaf surfaces and determining the key factors will help to screen tree species with high-efficiency PM reduction and improve the air purification function of green spaces. PM 2.5 retention experiments were conducted in a wind tunnel using 1800 branches from 30 species with different morphological structures under wind speeds of 1, 3.5, and 8 m/s. Eight comprehensive variables (PC1–PC8) of plant morphological structure were extracted by principal component analysis , and their relationships with PM 2.5 retention and the main influencing factors were explored by stepwise regression models. Under all of the wind speeds, the totality characteristic (PC1) (composite variable of factors including volume and total surface area) and surface area/weight density (PC2) of plant branches and leaves were the two most significant influencing factors, and they had negative effects. In addition to the aforementioned two common key factors, the leaf size (PC5) and surface roughness (PC7) were the two key positive factors at wind speeds of 1 and 3.5 m/s, while the number of branches and leaves (PC3 and PC4, respectively) were the two key positive factors at a wind speed of 8 m/s. Generally speaking, with the increase of wind speed, the effect of leaf morphological characteristics on PM 2.5 retention decreased, while the crown structure characteristics became more significant. Compared with leaf morphological characteristics, the crown morphological structure variables had greater variability and a greater impact on PM 2.5 retention. Crown morphological structure should be given more importance in screening high-efficiency PM retention tree species.
危险品化学品经营许可证（带存储）