不同季节路侧紫丁香绿带滞尘机制研究

Dust Retention Mechanism of Syringa oblata Green Belt on Roadsides in Different Seasons

为评估路侧紫丁香绿带的滞尘能力及紫丁香叶内的重金属含量,以呼和浩特市5条道路两侧紫丁香带为研究对象,采用实地测试法、质量差值法测定紫丁香带对不同粒径颗粒物的消减能力及PM消减率与微气候因子的关系;利用扫描电镜、能谱法观测紫丁香叶表面结构、颗粒物特征,分析紫丁香叶表面重金属相对含量,并利用电感耦合等离子质谱法测试叶内重金属浓度。结果表明:1)夏季路侧紫丁香绿带对各粒径PM的平均消减效应强于秋季、春季以及冬季;2)紫丁香叶表面具有吸滞颗粒物和多种重金属元素的能力,且各元素的相对百分含量因季节的不同而有差异;3)路侧绿带紫丁香叶内10种重金属元素的含量以秋季最高,夏季次之,春季最少,且以Fe、Al、Mn、Ba、Zn的含量较高,Pb、Cr、Cd、Co、Ni含量较低,这些元素与人为排放直接相关;4)紫丁香绿带对PM的消减率与空气温度、湿球温度和露点温度呈显著负相关,与相对湿度呈正相关,与风速则无明显相关性,且与紫丁香叶内重金属含量呈正相关。研究结果可为提高植物滞尘效应,改善城市道路绿地建设和大气环境提供科学的方法、理论依据和技术指导。

In order to evaluate the dust retention capacity of the roadside clove(Syringa oblata)green belt and the content of heavy metals in the leaves,the clove belt on both sides of five roads in Hohhot City was taken as the research object.The field test method and the mass difference method were used to determine the reduction ability of the clove belt to different particle sizes and the relationship between PM reduction rate and microclimate factors.The surface structure and particle characteristics of clove leaves were observed by electron scanning microscope and energy spectrum.The relative contents of heavy metals on the surface of clove leaves were analyzed.The concentrations of heavy metals in the leaves were measured by inductively coupled plasma mass spectrometry.The results showed that 1)in summer,the average reduction effect of clove green belt on PM particle size was stronger than those in autumn,spring and winter.2)The surface of clove leaves had the ability to adsorb particulate matter and many heavy metal elements,and the relative percentage content of each element varied with seasons.3)The contents of 10 heavy metal elements in clove leaves of roadside green belt were the highest in autumn,the second in summer,and the least in spring.The contents of Fe,Al,Mn,Ba,Zn were higher,and the contents of Pb,Cr,CD,Co,Ni were lower.These elements were directly related to man-made emissions.4)The reduction rate of PM by clove green belt was significantly and negatively correlated with air temperature,wet bulb temperature and dew point temperature,positively correlated with relative humidity,but not significantly correlated with wind speed,and positively correlated with the content of heavy metals in clove leaves.The research results can provide scientific methods,theoretical basis and technical guidance for improving plant dust retention effect,urban road green space construction and atmospheric environment improvement.