LAUSR

Abstract: A quantitative comparative analysis of PM accumulation on boles, branches and leaves is necessary to better understand the reduction of airborne PM by trees. This study compared the total water-insoluble particle accumulation mass per unit area, the distribution of water-insoluble particle size fractions, and the accumulation masses and compositions of water-soluble ions among different vegetative organs. The average accumulation capacity of water-insoluble particles was as follows: leaf epicuticular wax (11.1 ± 4.4 μg/cm2), leaf surfaces (22.0 ± 3.2 μg/cm2), terminal branch surfaces (101.6 ± 47.0 μg/cm2), perennial branch surfaces (92.7 ± 20.0 μg/cm2), and bark surfaces (1719.9 ± 684.7 μg/cm2). Bole bark surfaces tended to accumulate the largest proportion of large particles, averaging 88 ± 4%. Branch surfaces and leaf epicuticular wax accumulated the largest proportions of fine particles, averaging 15 ± 5%. The total masses of water-soluble ions were 18 ± 10%, 33 ± 13% and 32 ± 6% of the total water-insoluble particles on boles, terminal branches and leaves, respectively. Leaf surfaces accumulated 2.2–6.0 times more SO2- 4 and NO 3 than did branch and bark surfaces.