Short communication: Total and leachable phosphorous in urban street tree leaves

Leaves of different tree species were leached with distilled water (pH 7.0 plus or minus 0.2) and rain water (pH 5.7 plus or minus 0.3) in laboratory glass cylinders to simulate the release of phosphorous (P) pollutant to urban runoff. An average of 106 plus or minus 52.1 g g-1 and 143 plus or minus 72.7 g g-1 (air dried weight) of P were leachable from entire leaves in 2_ hours in distilled water and rain water, respectively; these represented 7.21% and 11.36%, respectively, of the total P in the leaves analyzed. The amount of leachable and total leaf P varied significantly (p < 0.05) among tree species but were not significantly (p < 0.05) affected by tree diameters. Fragmented leaves released more than twice as much phosphorous as intact leaves. These findings point to leaves as a source of urban runoff P.