Aerosols in the atmosphere - Air Pollution Modeling and Its Application - page 399

5.5 Chemical Composition Change of Aerosols Along
Long-Range Transport Paths

M. Astitha 1,2 , C. Spyrou 1 , G. Kallos 1 , H.A.C. Denier van der Gon 3 ,
A.J.H. Visschedijk 3 , and J. Lelieveld 2,4

1

University of Athens, School of Sciences, Faculty of Physics, Department of Environmental
Physics-Meteorology, Atmospheric Modeling and Weather Forecasting Group, University
Campus, Bldg. PHYS-V, Athens 15784, Greece
2

Energy, Environment and Water Research Centre, The Cyprus Institute, Athalassa Campus,
Nicosia, Cyprus
3

TNO Built Environment and Geosciences, Laan van Westenenk 501, P.O. Box 342, 7300
AH Apeldoorn, The Netherlands
4

Max Planck Institute for Chemistry, Becherweg 27, 55128 Mainz, Germany

Abstract The chemical composition of atmospheric aerosols is influenced by a
variety of physical-chemical interactions with the gas phase depending on ambient
conditions. Following the model development presented during the previous 29th
NATO/SPS meeting, where the third generation pollutants were introduced in a
regional chemical transport model, improvements in the heterogeneous uptake of
gases at the surface of dust particles have been implemented as presented in this
work. Our main objective is to analyze these improvements in view of long-range
transport paths. It is shown that after 2-10 days the aerosols constitute a mixture
of natural and anthropogenic species, of which the chemical characteristics sub-
stantially deviate from the freshly emitted particles.

Keywords Aerosols, dust, heterogeneous chemistry, long-range transport

1. Introduction

Changes in the chemical composition of atmospheric aerosols can occur through a
variety of physical and chemical mechanisms. These encompass homogeneous
and heterogeneous reactions and mixing of pollutants of different physical state
and origin (gas and particulate, natural and anthropogenic). The aerosol chemical
composition is altered during transport, known as “aging” from externally to
internally mixed aerosols. Continuous model development is needed to realistically
represent the complex physico-chemical processes and assess the changes in the
chemical composition of the transported aerosols. The first steps of this development
were presented during the previous 29th NATO/SPS Meeting.