Modelling the uptake of air pollutants by urban green in the city of Rome

Modelling plant-atmosphere interactions in urban environmenthave being raising an increasing interest in recent years,with the purpose to assess the effects of vegetation managementon urban air quality. In particular, it is widely knownthat vegetation removes tropospheric ozone (O3) by stomataland non stomatal uptake. Several authors have quantified theability of the so called ‘urban forest’ to ameliorate urban airquality, by estimating the amount of ozone, as well as that ofother pollutants, removed by trees and shrubs in differenturban areas. Here we present the results of a modellingexercise, implemented in the frame of the HE.R.E.P.L.U.S.(HEalth Risk from Enviromental Pollution Levels in UrbanSystems) Project, funded under EU FP7. Our aim was toestimate the amount of O3 removed by evergreen anddeciduous broadleaved trees in the Municipality of Rome(ab. 128530 ha), to quantify the role of urban woodyvegetation in a Mediterranean megacity. Ozone fluxes weresimulated for each day of the reference year, and referred tounitary area of soil surface, based on O3 air concentration andplant stomatal conductance for each vegetation type. The latterwas simulated through a semi-empirical process-based model(MOCA-Flux) originally developed to estimate the net primaryproductivity of plant community, and based on the ‘big leaf’assumption. The model has been parameterized by usingphysiological and structural data collected, during differentfield campaigns, on the main woody species in the Romemetropolitan area. The simulation was run for the year 2003–04, characterized by different climatic conditions that affectedplant functional performance. In the year 2003, vegetation ofthe five sanitary districts of the Rome Municipality removed atotal of 4.90, 4.16 and 3.91 g/m2 of O3 for evergreenbroadleaves, deciduous broadleaves and conifers, respectively.These results are coherent with what reported in literature,showing that vegetation could contribute in improving airquality in urban areas. Further activities are currently inprogress, aimed at estimating the amount of PM10 captured bytree vegetation in this area.