Fe²⁺ in ice cores as a new potential proxy to detect past volcanic eruptions

Volcanic eruptions are widely used in ice core science to date or synchronize ice cores. Volcanoes emit large amounts of SO₂ that is subsequently converted inthe atmosphere into sulfuric acid/sulphate.Its discrete and continuous quantification is currently used to determine the ice layers impacted by volcanic emissions, but available high-resolution sulphate quantification methods in ice core (Continuous Flow Analysis (CFA)) struggle with insufficient sensitivity. Here, we present a new high-resolution CFA chemiluminescence method for the continuous determination of Fe²⁺ species in ice cores thatshowsclear Fe²⁺
peaks concurrent with volcanicsulphate peaks in the ice core record. The method, applied on a Greenland ice core, correctly identifies all volcanic eruptions from between 1588 to 1611 and from 1777 to 1850. The method has a detection limit of ∽5pgg⁻¹ and a quadratic
polynomial calibration range of up to at least 1760 pg g⁻¹. Our results show that Fe²⁺
is a suitable proxy for identifying past volcanic events.