北京奥森公园侧柏林空气颗粒物不同季节变化规律

Seasonal Variation of Airborne Particulate Matter of Platycladus orientalis Forest in Olympic Forest Park of Beijing

为了对城市森林公园内游憩林的休闲游憩功能进行开发与利用,通过对北京奥林匹克森林公园侧柏林内外一年四季4种粒径空气颗粒物浓度全天24 h监测,并同步观测空气温湿度、风速、光照等气象因子,分析了林内外不同粒径颗粒物浓度的四季变化、日变化和小粒径颗粒物所占比例日变化规律,并对各粒径颗粒物与小气候因子之间的相关性和显著性进行分析。结果表明:侧柏林内外空气颗粒物浓度虽然在不同季节表现出不同的变化规律,但总体来说,林缘的均值高于林内均值,且夜间浓度高于白天,且四季均在5:00—7:00时间段不同程度达到峰值;从不同粒径颗粒物浓度的四季变化来看,林内总悬浮颗粒物(total suspended particulate,TSP)、PM_(10)和PM_(2.5)浓度的高低排序为:冬季>秋季>夏季>春季,PM_(1.0)颗粒物浓度的排序为:冬季>夏季>秋季>春季;林缘TSP、PM_(10)和PM_(1.0)浓度的高低排序与林内一致,而PM_(2.5)浓度的高低排序为:冬季>夏季>秋季>春季;林内外小粒径颗粒物所占比例的四季变化:与颗粒物浓度的季节变化相似均是冬季最大,夏季次之,秋季、春季最小;在一定范围内,林内外空气颗粒物浓度与相对湿度、光照均呈正相关,温度和风速呈负相关,且林缘的颗粒物浓度与风速呈显著负相关,随着粒径的减小,相关性变大。说明侧柏林内较林缘相比有较好的滞尘效果,适合保健型园林的开发和建设。

For the development and exploitation of the recreational functions of urban forest parks,the concentration of four kinds of air particles inside and outside the Platycladus orientalis forest in Beijing Olympic Forest Park were monitored 24 hours a day throughout the year,and the air temperature and humidity,wind speed,light and other meteorological factors were simultaneously observed,the seasonal and daily variation of four kinds of particles inside and outside the forest and the correlation and significance between each sized particulate matter and microclimate factors were analyzed.The results show that although the variation rule of the concentration of air particulate matter inside and outside the Platycladus orientalis forest varies with the change of seasons,but generally speaking,the average concentration value at the edge of the forest is higher than that inside the forest,and the concentration at night is higher than that of the day,and the concentration reaches the peak to different degrees from 5:00 to 7:00 in all seasons.From the seasonal changes of the concentration of different sized particles,the rank of the concentration of total suspended particulate(TSP),PM_(10) and PM_(2.5) in the forest are:winter>autumn>summer>spring,while the rank of the concentration of PM_(1.0) particles is:winter>summer>autumn>spring.The rank of TSP,PM_(10) and PM_(1.0) concentrations in the forest edge are consistent with that inside the forest,while the rank of PM_(2.5) concentration is:winter>summer>autumn>spring.The seasonal variation of the proportion of small particle size particles inside and outside the forest:similar to the seasonal variation of particle concentration,it is the largest in winter,the second in summer,and the smallest in autumn and spring.Within certain range,air particulate matter concentration inside and outside the forest is positively correlated with relative humidity and light,while temperature and wind speed are negatively correlated,and at the forest edge,the concentration of particulate matter is significantly negatively correlated with wind speed.As the particle size decreases,the correlation becomes greater.It shows that the inner side of Platycladus orientalis forest has better dust retention effect than forest edges,and is suitable for the development and construction of health-care gardens.