Measurements of submicron organonitrate particles: Implications for the impacts of NOx pollution in a subtropical forest

Organonitrates (ONs) are an important component of atmospheric aerosols that signify the perturbation of nitrogen oxides (NOx) pollution in the remote atmosphere. This study investigated the mass concentration and molecular composition of ONs in submicron particulate matters (PM1) at a subtropical forest site (Xitou), which located downwind the Taichung metropolis in the Central Taiwan. Here we showed that transport of urban air pollution with local circulations caused elevation in the ambient concentration of ONs in the forested area. In addition, the levels of ONs were positively correlated with ozone mixing ratio and were negatively correlated with the relative humidity, suggesting that the ONs were regulated by photochemistry and hydrolysis. The results also showed that the mass concentration of the ONs was significantly correlated with the number density of nanoparticles (d