Climatic Controls on a Holocene Mercury Stable Isotope Sediment Record of Lake Titicaca

Mercury (Hg) records in sediment archives inform past patterns of Hg deposition and the anthropogenic contribution to global cycling. Natural climate variations complicate interpretation accumulation rates (HgARs), warranting additional research. Here, we investigated stable isotopes a ca. 8k year-long core Lake Titicaca combined isotopic data with organic biomarkers biogeochemical measurements. A wet period early Holocene (8000–7300 BP) induced strong watershed erosion, leading high HgAR (20.2 ± 6.9 μg m–2 year–1), which exceeded 20th century (8.4 1.0 year–1). Geogenic input dominated during (fgeog = 79%) played minor role mid- late (4500 BP present; fgeog 20%) when atmospheric dominated. Sediment Δ200Hg values absence terrestrial lignin suggest that direct lake uptake Hg(0), subsequent algal scavenging Hg, represented an important pathway (42%) Holocene. During episodes (2400 present), Hg(II) was dominant source (up 82%). Δ199Hg photochemical reduction re-emission Hg(0) occurred from surface. show promise as proxies for understanding history sources transformations help disentangle factors influencing observed archives.