Variations in Pb-210 concentrations in atmospheric aerosol and deposition in Toki City, Gifu Prefecture, over the last 10 years.

Abstract

To understand the regional characteristics of the atmospheric environment, we have observed the atmospheric concentration and deposition flux of both beryllium-7 and lead-210 in Toki City, Gifu Prefecture, Japan, since 2014. In this study, we focused on the atmospheric behavior of lead-210. The concentrations of lead-210 after the summer of 2022 were higher than those before summer 2022. Atmospheric concentrations of lead-210 were observed as double peaks in spring and fall and showed low in summer. Deposition fluxes of lead-210 tended to be low in winter. Comparing the monthly average concentration of lead-210 until 2021 with the monthly average concentration of lead-210 after 2022, it increased from 0.77 mBq/m³ to 1.2 mBq/m³ for atmosphere and from 19 Bq/m² to 34 Bq/m² for deposition. We discuss the causes of the increase in lead-210 concentrations, including the results of backward trajectory analysis, measurements of trace element concentrations, and weather data.