重庆缙云山4种典型林分的大气颗粒物浓度差异及不同大气条件影响研究

以重庆缙云山为例,对4种典型林分(毛竹林、阔叶林、针叶林、苦竹林)夏季和秋季PM2.5进行观测,并选取典型天气,对不同粒径颗粒物(TSP、PM10、PM2.5和PM1)进行检测,研究西南地区典型林分PM2.5的季节变化和日变化,选取典型天气类型,研究其大气颗粒物浓度变化的影响。结果表明:PM2.5质量浓度秋季高于夏季,不同林分夏季颗粒物浓度差异不显著,秋季苦竹林明显高于其他3种林分。PM2.5质量浓度日变化趋势为上午>中午>晚上,4种林分2个时段PM2.5下降规律在夏季有较大不同,秋季有较高的一致性。4种典型天气条件下,“雨后晴天”颗粒物浓度最低,尤其是细颗粒物。说明降雨对颗粒物的消减有一定的积极作用。“伏旱天”颗粒物浓度显著高于其他3种典型天气。不同天气条件对毛竹林细颗粒物、针叶林4种粒径颗粒物和苦竹林4种颗粒物浓度的影响差异均显著。“雨后晴天”和“连续晴天”对阔叶林4种粒径颗粒物影响差异均不显著。 

Difference in the concentration of atmospheric particles of four kinds of typical forest stands and the influence of different atmospheric conditions in Jinyun Mountain,Chongqing of southwestern China

Taking Jinyun Mountain in Chongqing, southwestern China as an example, we observed PM2. 5 in four kinds of typical forest stands ( Phyllostachys heterocycla forest, broadleaved forest, coniferous forest and Pleioblastus amarus forest) in summer and autumn seasons, and detected particles of different sizes ( TSP, PM10 , PM2. 5 and PM1 ) at different time of the day in typical weather of different seasons to explore how typical weather conditions influence the concentrations of atmospheric particles of varying diameters in these forests in southwestern China. The results showed that:PM2. 5 mass concentrations were higher in autumn than in summer. There was no difference in the concentrations of different particles in the four kinds of forest in summer, while in autumn, the concentrations of particles in Pleioblastus amarus forest were significantly higher than those in other three kinds of forest. The diurnal variation in PM2. 5 followed the order of morning > noon > night. PM2. 5 concentration declined irregularly in summer, while it was just the opposite in autumn. Under four typical weather conditions, the particle concentration was the lowest after rain, especially for fine particles, showing that rainfall played a positive role in reducing particulate matters. Concentrations of particulate matters were significantly higher in summer drought weather than in the other three typical weather conditions. Different weather conditions had significant influence on the concentrations of particulate matters in Phyllostachys heterocycla forest, coniferous forest and Pleioblastus amarus forest. The sunny weather after rain and continuous sunny weather had no significant influence on the concentrations of particulates in the broadleaved forest.