Revisiting dry deposition modelling of particulate matter on vegetation at the microscale

This study presents dry deposition experiments on real grownHedera helix in a wind tunnel setup with wind speeds from 1 to 4 m s\(^{-1}\) and PM consisting of a mixture of soot (0.02 - 0.2\(\upmu \)m) and dust particles (0.3 - 10\(\upmu \)m). Significant factors determining the collection efficiency (%) were particle diameter and wind speed, but relative air humidity and the type of PM (soot or dust) did not have a significant influence. Zhang ’s model outperformed Petroff’s model for particles< 0.3\(\upmu \)m, however the inclusion of turbulent impaction in Petroff ’s model resulted in better agreement with the measurements for particles> 2 - 3\(\upmu \)m. The optimised model had an overall root-mean-square-error of\(\sim \) 4% for collection efficiency (CE) and 0.4 cm s\(^{-1}\) for deposition velocity (\(v_d\)), which was shown to be highly competitive against previously described models. It can thus be used to model PM deposition on other plant species, provided the correct parameterisation of the drag by this species. A detailed description of the spatial distribution of the vegetation could solve the underestimation for particle sizes of 0.3 - 2\(\upmu \)m.
Source: Air Quality, Atmosphere and Health - Category: Environmental Health Source Type: research