The purpose of this project is to evaluate the uptake rate of benzene and formaldehyde by common trees in Taiwan. The tested plant species include 6 trees ( champhor tree, Burma coast padauk, Formosan michelia, Formosan ash, red cedar, and zelkova), 6 shrubs ( golden dewdrop, azalea, common lantana, jasmin orange, Chinese ixora, and South American wax mallow), and 4 indoor plants( umbrella plant, Malabar chestnut, Chinese fan palm, and bird’s nest fern). There are four major tasks included in this one year project: (1) To review all the related literature, including the environmental factors that affect the pollutant uptake rate and the plant species with high pollutant uptake rates; (2) To measure the pollutant uptake rates of both pollutants by all the 16 plant species with instrument; (3) To compare the pollutant uptake rates when plants are exposed in different shading, light intensity, soil medium, biological clock and carbon dioxide conditions; (4) To estimate the yearly uptake rates of benzene and formaldehyde by the tree plant species in the parks in Taiwan. Results showed that benzene is uptaken most effectively by azalea, and formaldehyde is uptaken most effectively by jasmin orange and Chinese ixora. The effects of environmental factors on pollutant uptake rates are: (1) Both pollutant uptake rates are decreased by shadowing, (2) Pollutant uptake rate under higher light intensity is generally higher than in those in lower light intensity, (3) Potting material does not influence the uptake rate, (4) Both pollutant uptake rates are reduced by the elevation of CO2 concentration, and (5) Most plants show higher pollutant uptake during daytime than those in nighttime. The yearly uptake rates of benzene and formaldehyde by the tree plant species have been estimated on the basis of these data. We therefore recommend that residents can grow these plants with higher pollutant uptake rates, such as red cedar, azalea, and umbrella plant are good for benzene uptake, while zelkova, azalea, and Chinese fan palm are good for cleaning the formaldehyde. The results shown in this report are useful especially for Taiwan EPA and other organizations to select the right tree species for growing in polluted areas and neighborhood parks in Taiwan. We suggest that Taiwan EPA should promulgate all these information to the residents and in the web to promote the application of green plants in cleaning the air pollution in Taiwan.

Pollutant uptake, Benzene, Formaldehyde