Aqueous speciation of Cu(II) within the fine particulate matters in Beijing air pollution

Transition metal ions (TMIs) are effective catalysts for atmospheric multiphase reactions that produces secondary air pollutants. The reactivity of TMIs depends on many factors, including metal's solubility and aqueous speciation, which can be complex in the urban air pollution conditions. In this study, we examined the aqueous speciation of Cu(II) within the fine particulate matters (PM2.5) in Beijing air pollution. Using visual MINTEQ model and the Beijing PM2.5 composition data obtained from previous publications, we predicted the distribution of Cu(II) in the forms of free ions, metal-organic complexes, and metal-inorganic complexes. Such a distribution is affected by pH and PM2.5 composition with a seasonal variation, which may further arise from the anthropogenic emission patterns. Our finding may provide useful dataset for parameterizing the kinetics of TMI-catalyzed multiphase reactions.