Work

Mercury isotopes in North Pacific sediments reveal vegetation expansion in warm climates

Year: 2025

Type: article

Abstract: Mercury (Hg) concentrations and isotope compositions in sedimentary rocks are widely used to trace volcanism, but their natural variabilities through climate changes remain to be fully understood. Here, we present Hg isotope records from the North Pacific Shatsky Rise, a region without direct terrestrial input, to reconstruct the evolution of open ocean Hg isotopes. During the early Holocene (11–8 ka), the sedimentary Δ199Hg increased from 0.16 ‰ to 0.21 ‰, along with the increase in δ13C of CO2 caused by the expansion of terrestrial vegetation. A higher Δ199Hg (0.23 ‰) is also observed during the warm Pliocene (3.8–2.5 Ma) with higher terrestrial productivity. By constructing a time dependent global Hg box model, we demonstrate that the higher open ocean Δ199Hg in warm climates reflects enhanced atmospheric Hg(0) uptake by terrestrial vegetation. This is likely driven by vegetation expansion and/or biome shifts, which absorb more gaseous Hg with lower Δ199Hg.

Source: Geochemical Perspectives Letters

DOI: 10.7185/geochemlet.2534