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作者

来源

URBAN FORESTRY & URBAN GREENING,Vol.30,P.62-71

语言

英文

关键字

Ecosystem services; NO2; Particulate matter; Passive samplers; PM2.5; Urban vegetation; URBAN TREES; PARTICULATE MATTER; NITROGEN-DIOXIDE; NO2 CONCENTRATIONS; VEGETATION BARRIER; ECOSYSTEM SERVICES; DRY DEPOSITION; QUALITY; FOREST; PARTICLES

作者单位

[Viippola, Viljami; Zhao, Wenlin; Mikola, Juha; Setala, Heikki] Univ Helsinki, Dept Environm Sci, Niemenkatu 73, FI-15140 Lahti, Finland. [Whitlow, Thomas H.] Cornell Univ, Sch Integrat Plant Sci, Sect Hort, Room 23,Plant Sci Bldg, Ithaca, NY 14853 USA. [Yli-Pelkonen, Vesa] Univ Helsinki, Dept Environm Sci, POB 65, FI-00014 Helsinki, Finland. [Pouyat, Richard] USDA Forest Serv R&D, 1400 Independence Ave, Washington, DC 20250 USA. Viippola, V (reprint author), Univ Helsinki, Dept Environm Sci, Niemenkatu 73, FI-15140 Lahti, Finland. E-Mail: viljarni.viippola@helsinki.fi

摘要

It is often stated that plants remove air pollutants from the urban atmosphere with their large leaf area, thus providing benefits - i.e. ecosystem services - for citizens. However, empirical evidence showing that localscale air quality is uniformly improved by urban forests is scarce. We studied the influence of conifer-dominated peri-urban forests on the springtime levels of NO2 and particle pollution at different distances from roads, using passive samplers and high time resolution particle counters in a northern climate in Finland. Passive samplers provided average values over a one month period, while active particle counters provided real time measurements of air pollution to mimic human inhalation frequency. NO2 concentrations were slightly higher in forests than in adjacent open areas, while passive particle measurements showed the opposite trend. Active particle monitoring campaigns showed no systematic forest effect for PM2.5, but larger particles were reduced in the forest, corroborating the passive sampling result. Attenuation rates of the mean values of the studied pollutants did not differ between the forest and open habitats. However, high time resolution particle data revealed a distance effect that was apparent only in the forest transect: peak events at the forest edge were higher, while peaks furthest from the road were lower compared to the open transect. Furthermore, the magnitude of PM2.5 peak events was distinctly higher at forest edge than equivalent distance in the open area. Vegetation characteristics, such as canopy cover and tree density, did not explain differences in pollutant levels in majority of cases. Our results imply that evergreen-dominated forests near roads can slightly worsen local air quality regarding NO2 and PM2.5 in northern climates, but that coarser particle pollution can be reduced by such forest vegetation. It seems that the potential of roadside vegetation to mitigate air pollution is largely determined by the vegetation effects on airflow.