Particulate matter(PM), one of the most important pollutants of traffic emission, threatens the health of urban ecosystems and citizens. Roadside trees play an important role in trapping PM, and the foliar PM load is ...Particulate matter(PM), one of the most important pollutants of traffic emission, threatens the health of urban ecosystems and citizens. Roadside trees play an important role in trapping PM, and the foliar PM load is a useful indicator for air PM pollution in road systems. To detect the relationships of foliar PM load with road structures, urbanization, and meteorology in road systems, we studied a widely-planted tree Sophora japonica L. in 100 roads and 10 yards of Beijing, China, and found that the foliar PM loads increased with the distances from the urban centre(DUC) linearly, while decreased with the road density. All-subsets regression analysis indicated that DUC, average monthly relative humidity, average monthly wind speed, and mean annual wind speed were the most important factors in predicting foliar PM load, rather than general situation of buildings and road cleanliness. The monthly relative humidity and monthly wind speed had a negative correlation to foliar PM, while the annual relative humidity and annual wind speed had a positive correlation to foliar PM. Suburban areas and these effective factors should be highlighted in PM control in Beijing.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.41430638)Special Found for Beijing Common Construction Project for Beijing Laboratory of Urban and Rural Ecological Environment(No.PXM2015_014207_000014)Grants from the Beijing Municipal Education Commission(No.PXM2019_014207_000099)
文摘Particulate matter(PM), one of the most important pollutants of traffic emission, threatens the health of urban ecosystems and citizens. Roadside trees play an important role in trapping PM, and the foliar PM load is a useful indicator for air PM pollution in road systems. To detect the relationships of foliar PM load with road structures, urbanization, and meteorology in road systems, we studied a widely-planted tree Sophora japonica L. in 100 roads and 10 yards of Beijing, China, and found that the foliar PM loads increased with the distances from the urban centre(DUC) linearly, while decreased with the road density. All-subsets regression analysis indicated that DUC, average monthly relative humidity, average monthly wind speed, and mean annual wind speed were the most important factors in predicting foliar PM load, rather than general situation of buildings and road cleanliness. The monthly relative humidity and monthly wind speed had a negative correlation to foliar PM, while the annual relative humidity and annual wind speed had a positive correlation to foliar PM. Suburban areas and these effective factors should be highlighted in PM control in Beijing.
文摘比较了我国产品、应用、设计标准采用的几种常规道路照明灯具配光分类方法;以某款LED路灯为例,依据光强数据计算9项指标,判断其配光类型及适用范围,并用DIALux evo做道路样本模拟,计算评估了照明质量合规性。结论包括:配光分类方法不仅要考虑灯具的截光性能,还应考虑光束宽度(角);纵横配光类型间关联定义的合理性有待验证;目前国际上推荐基于IES室外灯具分类系统LCS对道路照明灯具进行BUG(Backlight, Uplight and Glare)分类,这是从眩光及干扰光限制角度进行的完善,而溢散光分类是对BUG分类的合并与简化。从产品角度,为了达到光度性能整体的平衡,必须在灯具配光类型各指标间进行折中,从而为不同类型的道路提供有针对性的产品;从应用角度,适当简化的配光类型较配光曲线和光强表更易理解和便于选型,建议生产商标称灯具的配光类型,推荐量化的适用范围以及适用的道路类型。
