Study of Dry Deposition and Atmosphere-Surface Exchange for Gaseous and Particulate Components

Abstract

To assess the impact of the atmospheric deposition of air pollutants on ecosystems, it is important to accurately estimate the deposition amounts. Compared to wet deposition, it is difficult to estimate the amounts of dry deposition, and there is still considerable uncertainty in the estimation accuracy. In this review, I provided an overview of a study on dry deposition and atmosphere-surface exchange mechanisms by flux observations, and assessments of atmospheric deposition by the inferential method, along with relevant studies from around the world. Flux observations were done by the gradient method or relaxed eddy accumulation method for ozone, sulfur dioxide, PM_2.5 sulfate, PM_2.5 nitrate, nitric acid, and ammonia sequentially carried out from 2002 to 2021. The observations were carried out above forest sites located in temperate, cool temperate, and tropical regions. Regarding the nitrogen components, observations were also carried out in agricultural fields. The large uncertainties of the deposition velocities of submicron particles above forests were specifically discussed considering some processes that are not considered in dry deposition models. The uncertainties of the observed deposition velocities were also discussed. Furthermore, I showed some results of the assessment of sulfur and nitrogen deposition in Japanese remote areas, and finally considered future atmospheric deposition study.