Lithium Isotope Geochemistry in the Barton Peninsula, King George Island, Antarctica

Lithium (Li) has two stable isotopes, Li-6 and Li-7, whose large relative mass difference is responsible for significant isotopic fractionation during physico-chemical processes, allowing Li isotopes to be a good tracer of continental chemical weathering. Although physical erosion is dominant in the Polar regions due to glaciers, increasing global surface temperature may enhance chemical weathering, with possible consequences on carbon biogeochemical cycle and nutriment flux to the ocean. Here, we examined elemental and Li isotope geochemistry of meltwaters, suspended sediments, soils, and bedrocks in the Barton Peninsula, King George Island, Antarctica. Li concentrations range from 8.7 nM to 23.3 pM in waters, from 0.01 to 1.43 ppm in suspended sediments, from 9.56 to 36.9 ppm in soils, and from 0.42 to 28.3 ppm in bedrocks. delta Li-7 values are also variable, ranging from +16.4 to +41.1 parts per thousand in waters, from -0.4 to +13.4 parts per thousand in suspended sediments, from -2.5 to +6.9 parts per thousand in soils, and from -1.8 to +11.7 parts per thousand in bedrocks. Elemental and Li isotope geochemistry reveals that secondary phase formation during chemical weathering mainly control dissolved delta Li-7 values, rather than a mixing with sea salt inputs from atmosphere or ice melting. Likewise, delta Li-7 values of suspended sediments and soils lower than those of bedrocks indicate modern chemical weathering with mineral neoformation. This study suggests that increasing global surface temperature enhances modern chemical weathering in Antarctica, continuing to lower delta Li-7 values in meltwater with intense water-rock interactions.

Automated summary

This study investigates the elemental and Li isotope geochemistry of meltwaters, suspended sediments, soils, and bedrocks in the Barton Peninsula, King George Island, Antarctica. The findings suggest that increasing global surface temperature enhances modern chemical weathering in Antarctica, leading to lower delta Li-7 values in meltwater with intense water-rock interactions.