Pollution history and colonial-induced increase in the transport of mercury from Australia to Sub-Antarctic islands: using mercury isotopes to trace the source

Mercury (Hg) is a volatile toxic metal with strong atmospheric mobility, making its biogeochemical cycle highly sensitive to climate change. A key challenge is distinguishing natural climate-driven variability from anthropogenic impacts. This study examines how colonisation and climate change have shaped Hg contamination across the Australia–Pacific region. Previous work shows increasing Hg deposition in remote environments since the colonial era. Here, we apply a multi-proxy framework—combining Hg isotopes, geochemistry, and robust chronologies derived from radiocarbon, lead-210, and plutonium dating—to lake sediments from southern Australia and sub-Antarctic islands (Macquarie and Campbell). These records allow us to separate long-range transport, anthropogenic emissions, invasive animal disturbance, and climate drivers such as the southern hemisphere westerly winds. By integrating isotopic, geochemical, and age-model data, we quantify Hg sources and accumulation rates, providing new insights into Hg cycling in lacustrine ecosystems under changing climate conditions.