Mercury Sources Between Zhongshan Station and Dome A, Eastern Antarctica Identified Using Mercury Stable Isotopes

Although mercury (Hg) is a neurotoxic metal of global relevance, its Antarctic biogeochemical cycles are not well characterized. Here, we present the total Hg (THg) distribution and stable isotopic fractionation between the Zhongshan Station and Dome A (1,248 km), in eastern Antarctica, to characterize THg sources and controlling factors. Surface snow samples and snow blocks similarly exhibited higher THg concentrations in the coastal and interior sections than the intermediate section. From the THg distribution and stable isotopic fractionation (notably for ²⁰⁰Hg and ²⁰²Hg), we inferred an adjacent oceanic Hg source for the coastal section and primary oceanic sources at 63°S–55°S and 50°S–45°S for the intermediate and interior sections, respectively. Snow drifting and postdepositional effects also influenced THg concentrations and stable isotopic fractionation, particularly in areas with marked terrain slope variations. Finally, the stratospheric contribution of THg near Dome A was negligible, with a possible transport pathway through the lower troposphere.