Abstract
In order to find out the interception or catching effects of park anb open space in the air pollution in the city, particularly in dust accumulation, the author investigated the distribution of dust amounts on the leaves of trees planted in the inner and outer Imperial Gardens, located in the center of Tokyo and condition of dust fixing on leaves of Pinus thunbergii.
1) Amounts of dusts accmulated on the tree leaves decreased as proceeds to the inner parts of Imperial Garden, decreasing to about 1/40 in amounts. This suggests that the extension of open space (space effects) and covering layer of trees planted in this open space (planting effects) have the cooperative effects of preventing dust accumulation on leaves in the city.
2) Usually over 80% of stomates of Pinus thunbergii leaves closed in the outer parts of Imperial Garden, but in the center, about 1 km apart, no or very few stomatal closing occurred.
3) The amount of dust accmulation on old leaves was from 30% to above 3 times greater than those on new leaves. Degree of stomatal closing of old leaves was higher that of new leaves.
4) Most asily dust accumulating part of Pinus leaves was the finely serrated edge of leaves and low amounts of dust accumulation on waving or flat parts of leaves were observed.
5) As dusts on leaves persisted even after raining, there will be need to wash leaves to keep from hard fixing of dusts on leaves and protect from growth inhibition of trees.
