Andres Yarce Botero, Santiago Lopez-Restrepo , Arjo Segers , O. Lucia Quintero , Arnold W. Heemink , Nicolas Pinel 

This work presents the implementation of the LOTOS-EUROS regional atmospheric Chemical Transport Model (CTM) on
Northwestern South America. The impact of land use and orography update in the model was analyzed to identify potential
vulnerable natural areas by quantifying atmospheric deposition pollutants. CTMs allow simulating the physical dynamics of
trace gasses and aerosols, including processes such as emission, chemical reactions, transport, and deposition. The deposition
of atmospheric contaminants like nitrogen dioxide (NO2) and ammonia (NH3) induces chemical fluxes in natural ecosystems,
with potential subsequent severe impacts like biodiversity loss. Due to the vast geographical diversity present in the study area,
the LOTOS-EUROS model was updated for the land and topography inputs to simulate more representative conditions for the
study region. Depositions were very sensitive for the change of land cover maps used in the model, and on the other side,
topography update impacts more in the high layer of the model above harsh terrain. Additional simulations for the updated
scenario using point sources were performed to identify the deposition area’s spatial extent for the principal Colombian cities.