ABSORPTION OF ATMOSPHERIC FORMALDEHYDE BY DECIDUOUS BROAD-LEAVED, EVERGREEN BROAD-LEAVED, AND CONIFEROUS TREE SPECIES

To estimate the effect of tree planting on atmospheric formaldehyde, t he absorption of formaldehylde by various tree species was examined. T he absorption rates varied from 8.6 (Japanese black pine) to 137 ng dm (-2) h(-1) ppb(-1) (Lombardy poplar) at 1000 mu mol of photons m(-2) s (-1), and the absorption rate increased in the following order: decidu ous broad-leaved tree species > evergreen broad-leaved tree species > coniferous tree spec;es. In experiments in which the light intensity w as varied, a linear relationship between the formaldehyde absorption r ate and the transpiration rate was observed for three tree species. Fr om the results obtained from a simplified gas diffusive resistance mod el, we can conclude that formaldehyde is absorbed through the stomata, and is rapidly metabolized by three tree species. Even at a high conc entration of about 2000 ppb, trees have the ability to absorb atmosphe ric formaldehyde for at least 8 h without any visible foliar injury. W e conclude that trees in general could act as an important sink for at mospheric formaldehyde.