Atmospheric particulate matter retention capacity of bark and leaves of urban tree species.

Urban vegetation can effectively filter and adsorb particulate matter (PM). However, limited studies have been conducted on the PM retention capacity of tree barks. This study investigated the ability of five common urban tree species in the Yangtze River Delta region to retain PM through their barks and leaves by conducting a 14-day tree PM retention experiment on the five tree species during autumn and winter. The results showed that (1) the PM retention per unit area of bark was 6.9 times and 11.8 times higher than that of leaves during autumn and winter, respectively; (2) when considering total surface area, bark and leaves exhibited comparable PM retention capacities at the whole-plant scale; (3) the ability of bark to retain PM is species-specific, which can be attributed to different bark morphology among different tree species; and (4) bark and leaves exhibited distinct preferences for retaining PM of different particle sizes, even when exposed to similar environmental conditions. This study highlights the remarkable ability of tree bark to PM removal and provides valuable insights into the role of urban trees in mitigating PM pollution. Furthermore, these findings can provide valuable insights into studies on dry deposition modelling, urban planning, and green space management strategies.