[High-frequency Responses to the COVID-19 Shutdown of Heavy Metal Elements in PM in Shanghai].

To study the evolution and sources of heavy metal elements in the urban atmosphere before, during (overlapped with Chinese Lunar New Year), and after China's COVID-19 shutdown, a multi-metal online analyzer was deployed to determine the trace elements in PM in Shanghai from January 1 to February 26, 2020. Meanwhile, source apportionment of the hourly measured heavy metal concentrations was performed using a PMF model, in which eight sources were identified. The results show that the concentrations of most elements presented a "V-shaped" trend, which was mainly influenced by emissions from fireworks (K, Cu, Ba as indicative elements), Se-related industry, road dust (Ca, Fe, Ba), and motor vehicles (Mn, Zn, Fe, Cu).

[High-frequency Evolution of Urban Atmospheric Ammonia and Ammonium and Its Gas-to-Particle Conversion Mechanism in Nanjing City].

In this study, hourly mass concentrations of atmospheric gases (mainly NH) and secondary inorganic aerosols (mainly NH, NO, and SO) in Nanjing City were continuously measured during the fall of 2018 by an online gas and aerosol chemical component monitor. The dataset was used to investigate the variation characteristics of ambient NH and NH during polluted and non-polluted periods, and to explore the potential chemical mechanism during gas-to-particle conversion between NH and NH. The results show that throughout the sampling period, the mean values (±1) of the mass concentrations of NH and NH were (15.