Numerical Study of the Impact of Dust-PM10 on VOCs Reduction in Coniferous Forest

BORIS KRASOVITOV, Rahul Tarodiya, Andrew Fominykh, Avi Levy, Itzhak Katra, Ben-Gurion University of the Negev, Israel

     Abstract Number: 98
     Working Group: Remote and Regional Atmospheric Aerosol

Abstract
Biogenic Volatile Organic Compounds (VOCs) are released by the forests. Forests also affect airflow and particulate matter (PM) concentration in the atmosphere. In this study, we performed a numerical analysis of the adsorption of VOCs above and inside coniferous forests by dust-PM10. The developed model is based on the application of theory of turbulent diffusion in the forest combined with the model of dust particles deposition to vegetation elements and VOCs adsorption by airborne dust particles. 3D modeling of the particulate flow using a discrete phase model, based on the Eulerian-Lagrangian approach, has been performed to investigate the dust deposition on the tree leaves. The modeling considered several forces influencing the particulate motion, namely, the drag force, buoyancy force, Brownian force, and Saffman’s lift force, along with a methodology to capture the particle deposition on the vegetation element, which is considered as a prolate ellipsoid approximating in shape to a leaf of coniferous trees (needles). Based on Computational Fluid Dynamics (CFD) modeling, the novel parameterization of the average particles collection rate is suggested. The validity of the model prediction is evaluated by comparison of the model of particle deposition on a Forest Canopy (PDFC) supplemented by parameterization of the average collection rate based on the CFD model with field measurement data. Further, the influence of particle size and wind velocity on VOCs reduction in coniferous forest are analyzed. It is observed that despite a significant decrease in the PM concentration along the forest, dust particles can reduce the concentration of VOC by 7-9 % on the leeward side of the forest. The results of the present study may help expand our knowledge on the spatial interaction of gases and solid particles in the atmosphere to provide more realistic estimates of the contribution of VOCs to the formation of ground-level ozone.