Mechanisms of Pollutant Exchange at Soil-Vegetation-Atmosphere Interfaces and Atmospheric Fate

The presence in the atmosphere of pollutants emitted from agriculture or impacting crop production, their concentration levels and their residence time depend on a series of physical, chemical and biological processes. This chapter describes the basic mechanisms and the main factors involved in air pollutant emissions and fate in agricultural systems. These include emissions to the atmosphere from fields or livestock husbandry, atmospheric transfers at various scales – from the proximity of the sources to regional and global scales –, atmospheric chemistry and deposition to ecosystem. These concepts are necessary to understand the context and various choices that can be made in terms of measuring air concentrations and emission/deposition fluxes and of modelling emissions, atmospheric fate – dispersion, transport, degradation – and deposition. The knowledge on these processes contributes to modelling the impact of agricultural sources on air quality and the impact of air pollution on ecosystems. It also helps identify levers for mitigating emissions from agriculture and impacts of air pollution on crops.