Trees absorb pollutants through the same process they take up nutrients, . stomata (pores on the surface of the leaf), roots and root hairs. Additional pollution is removed by capture on their leaf/needle and bark surfaces. Taylor and Constable (1994) estimated for SO2 and O3 that 70% and 80% of the pollution absorbed is internal to the leaf. For particulates, the main wet absorption route is through tree roots (Broadmeadow and Freer-Smith, 1996), whereas the main dry absorption route is through deposition on leaf and bark surfaces. Occult deposition is also difficult to measure and may only be important in.
