重庆市区道路旁树叶表面沉积物形态和成分对城市空气质量的反映

Reflection of Morphology and Composition of Sediments on Roadside#br#Leaf Surface on Urban Air Quality in Chongqing,China

观察和分析城市道路旁树叶表面沉积物的形态和元素成分,获取城市不同区域空气污染的主要颗粒成分,测定沉积物中元素含量,进而推测污染来源。夏季(7月)和冬季(1月)分别摘取住宅区(杨公桥)、商业区(观音桥)、公园区(照母山)3地道路旁树叶,应用扫描电子显微镜和能谱分析仪分析树叶表面沉积物的形态和元素成分。结果表明,夏季树叶表面颗粒物少于冬季,公园附近树叶颗粒物比其余两处少,住宅区PM10颗粒物较多,商业区PM2.5颗粒物较多,颗粒物主要成分为碳、氧、硅、钾、钙、镁、铝、铁、磷、硫等。重庆主城空气质量较好,夏季空气质量优于冬季,公园区空气质量优于其他两区域。空气颗粒物主要来源是土壤扬尘、汽车尾气、建筑扬尘,住宅区建筑扬尘污染较其他两区域高,商业区汽车尾气污染较其他两区域高。无铅汽油的应用使城市空气颗粒物中铅含量已低于能谱仪可检出值。

This article aims to observe and analyze the morphology and element composition of the leaf surface sediments beside urban roads,to obtain the main particle composition of air pollution in different areas of the city,to determine the element content in the sediments,and then to infer the source of pollution.In summer(July)and winter(January),leaves were collected from residential area(Yanggongqiao),commercial area(Guanyinqiao)and park area(Zhaomushan Mountain Park)respectively,and the morphology and element composition of leaf surface sediment were analyzed by the scanning electron microscope(SEM)and energy dispersive spectrometer(EDS).The results showed that the particles on the surface of leaves in summer were less than those in winter,and the particles near the park were less than those in the other two areas.There were more PM10 particles in residential areas and more PM2.5 particles in commercial areas.The main components of particles were carbon,oxygen,silicon,potassium,calcium,magnesium,aluminum,iron,phosphorus,sulfur etc.The air quality of Chongqing main city is good,and the air quality is better in summer than in winter as well as better in the park area than in the other two areas.The main sources of airborne particulates are soil dust,automobile exhaust and construction dust.Construction dust pollution in residential areas is higher than that in the other two areas,and automobile exhaust pollution in commercial areas is higher than that in the other two areas.The application of lead-free gasoline has made the lead content in urban air particulates lower than the detectable value of the spectrometer.The application of unleaded gasoline makes the lead content in urban air particulate matter lower than the value that can be detected by energy spectrometer.