Abstract:The dynamics of particulate matter (PM) deposition and subsequently cleaning of the leaves during the season are probably greatly affected by weather conditions, such as precipitation, wind and extraneous dust storm. Such information is necessary for determining total PM deposition during a season or year. It may also be important in designing the surface of the ground under vegetation, which should be adapted to increase deposition and immobilization of pollutants and prevent further re-suspension. In a study carried out in spring under typical weather conditions (e.g., continuous sunny day, medium-rainfall, small rainfall, strong wind, extraneous dust storm), the ability of four plant species including Pinus tabuliformis, Ligustrum lucidum, Viburnum odoratissimum, and Trifolium repens to accumulate PM from ambient air in urban area was investigated. The effects of rainfall, relative humidity, maximum wind speed and PM10 (particulate matter with an aerodynamic diameter less than 10 μm) concentrations on PM deposition on foliage were also determined. The results showed that the amount of PM accumulated on leaves (g/m2) differed considerably between plant species, and decreased in this order: P. tabuliformis (4.57-5.45) > V. odoratissimum (2.23-5.85) > L. lucidum (2.14-4.27) > T. repens (0.12-0.38). The amount of PM accumulated on leaves of P. tabuliformis and T. repens remained relatively constant in the whole spring. The species like P. tabuliformis can emit sticky materials and makes the particulate matters hard to be removed by precipitation and wind. While the leaves of T. repens has water repellency characteristics and makes the particulate matters hard to be captured. Among the species analyzed, precipitation and wind removed a considerable proportion of PM accumulated on leaves of V. odoratissimum and L. lucidum. A decrease in the amount of PM accumulated on leaves was observed after two days of medium-rainfall (17.1, 14.8 mm) for V. odoratissimum (62%) and L. lucidum (50%), compared with the maximum values observed. Moreover, a decrease of about 30% in the amount of PM deposition was found after light rain and strong wind for L. lucidum. With the increase of the maximum wind speed, the PM retention amounts of L. lucidum and V. odoratissimum firstly increased and then decreased, and the peak value was reached at a maximum wind speed of 14 m/s. The influence of relative humidity on leaf PM retention amount only occurred when its value over 80%, leading to a decrease in leaf PM retention amount. The saturation of PM storage capacity of leaves of L. lucidum and V. odoratissimum could occur in four to five days in a heavily polluted condition. These results showed that both, the dynamics of deposition and PM removal by rain and wind during the season need to be considered when evaluating the total and actual effect of vegetation in pollutant remediation.