太原市森林公园林带对空气PM2.5的净化效率

开展城市绿地滞尘效应研究对指导城市绿地建设具有重要科学意义。为了研究城市交通主干道周边绿地的滞尘效应，以太原市森林公园西侧紧邻滨河东路南北长600 m，东西宽100 m的针叶混交林带为研究对象，在林带最西侧与道路交界处设对照点（0 m），由西向东垂直于路面在林带内分别设置20、40、60、80 m 4个监测点，用中流量大气PM2.5采样器（100 L/min）在各点对PM_2.5进行日间采样，分析林带内PM_2.5浓度的变化特征并计算林带对PM_2.5的净化效率。结果表明:1）林带宽度影响其对大气PM_2.5的净化效率，从20~60 m的净化效率逐渐提高，80 m处略低于60 m；2）林带对局部空气PM_2.5净化效率与区域空气质量呈负相关，当空气质量为优良时，林带可以有效地降低局部PM_2.5，当空气质量为中重度污染时，林带20~40 m宽处会聚集较高浓度的PM_2.5；3）林带内分时段净化效率显示，9:30-11:00的净化效率最低，12:30-17:00净化效率较高，且15:30-17:00林内PM_2.5质量浓度最低，提示该时段适宜市民在公园内活动。

Characteristics of the Variation of PM 2.5 Concentration in Forest Belt of Taiyuan Forest Park

The study of dust retention effect is of great significance to guide the construction of urban green space scientifically and rationally.In order to study the dust detention effect of urban green space on main traffic roads,the typical coniferous mixed forest belt(600 m south-north×150 m east-weast)adjacent to east Binhe road on the west side of Taiyuan Forest Park was taken as the research object,and five monitoring points,0(control point,and this point located at the edge between forest belt and Binhe road),20,40,60,80 m,were set up.Then PM 2.5 of each point was monitored by mid-flow sampler during the day,and characteristics of the variation of PM 2.5 concentration in the forest belt were analyzed.The results showed that:1)the width of the forest belt affected the purification efficiency of PM 2.5,and the purification efficiency increased from 20 m to 60 m while slightly lower than 60 m at 80 m,indicating that the 60m width of forest belt on the main traffic road can effectively purify air particular.2)The purification efficiency of PM 2.5 for local air was negatively correlated with regional air quality.When air quality was good,the forest belt could effectively reduce the local PM 2.5 concentration.When air quality was moderately or severely polluted,the forest belt would focus on the higher concentration of PM 2.5 at 20-40 m width,indicating that the forest belt ecosystem has a threshold value for dust detention.3)The purification efficiency of different time periods in the forest belt showed that the purification efficiency was the lowest at 9:30-11:00,higher at 12:30-17:00,and the PM 2.5 concentration in the forest was the lowest at 15:30-17:00,which is suitable for public activities in the park.