Absorption of atmospheric C-2-C-5 aldehydes by various tree species and their tolerance to C-2-C-5 aldehydes

To estimate the effect of tree planting on atmospheric C-2-C-5 aldehydes, a study was made on the absorption of, and tolerance to, C-2-C-5 aldehydes b y various tree species. The absorption rates ranged from 10.2 for acetaldeh yde (Japanese black pine) to 107 ng dm(-2) h(-1) ppb(-1) for n-valeraldehyd e (locust) at 1000 mu mol of photons m(-2) s(-1) The absorption rates of C- 2-C-5 aldehydes increased in the following order: coniferous tree species < evergreen broad-leaved tree species < deciduous broad-leaved tree species; trees exhibiting higher absorption rates of C-2-C-5 aldehydes had greater transpiration rates. In experiments with three species in which the light i ntensity was varied, there was a linear relationship between the absorption rate of a particular C-2-C-5 aldehyde and the transpiration rate. In compa rison with the absorption rates estimated from a simplified gas diffusive r esistance model, we conclude that C-2-C-5 aldehydes are absorbed through th e stomata and are metabolized fairly rapidly within the leaf tissue, althou gh the absorption rates are slightly less than the estimated potential abso rption rates. At total C-2-C-5 aldehyde concentrations of less than approxi mately 3000 ppb, two orders of magnitude larger than the actual indoor or o utdoor concentrations, evergreen broad-leaved tree species and coniferous t ree species have the ability to absorb atmospheric C-2-C-5 aldehydes for at least 8 h without any visible foliar injury. Although deciduous broad-leav ed tree species have lower tolerance to gaseous C-2-C-5 aldehydes than ever green broad-leaved and coniferous ones, they have enough ability to absorb atmospheric C-2-C-5 aldehydes at total concentrations of approximately 400 ppb without visible foliar injury. We conclude that trees in general could act as an important sink for atmospheric C-2-C-5 aldehydes. (C) 1998 Elsevi er Science B.V. All rights reserved.