Abstract Atmospheric particulate‐bound mercury (PBM), adsorbed onto aerosols like TSP and PM2.5 (PBMTSP and PBM2.5), is crucial to the Hg biogeochemical cycle. However, the mechanisms underlying the formation and transportation of PBM remain unclear. This study aims to explore these mechanisms by utilizing Hg isotopes and collecting PBMTSP and PBM2.5 samples at five distinct sites in North China. Both PBMTSP and PBM2.5 exhibited positive odd and even mass‐independent fractionation (MIF), with Δ199Hg values in PBM2.5 enriched by 0.25 ± 0.35‰ relative to PBMTSP. The slopes between Δ199Hg and Δ201Hg, along with sulfur MIF and backward trajectories, suggest that intense photoreduction reactions during long‐distance and high‐altitude transport are the primary driver of the elevated Δ199Hg in fine particulate matter. Importantly, significant positive MIF signatures can occur not only in remote areas but also in anthropogenic Hg emission regions, underscoring the underestimated role of atmospheric transport, particularly on clean days.
Observations from the Little Bunker
Last updated: October 16, 2025 02:57 AM
Atmospheric CO₂
424.4 ppm
+18.2
ppm/year
Atmospheric CH₄
1933.54 ppb
+12.29
ppb/year
Global Temperature
+1.48 °C
Peak: +1.73°C
World Population
8.1 billion
+67
million/year