New chemical signatures from Weißseespitze ice cores (Eastern Alps): pre-industrial pollution traces from Roman Empire to early modern period

Introduction High-altitude glaciers in the Western European Alps have yielded crucial records of anthropogenic air pollution, revealing a sharp rise in pollutant levels over the past two centuries due to industrialisation. In contrast, studies in the Eastern Alps have been scarce, as their lower-elevation glaciers were often considered less suitable for preserving undisturbed records. Nevertheless, recent findings indicate that, under specific conditions, cold ice frozen to bedrock can persist below 4,000 m. This is exemplified by the Weißseespitze (WSS) summit ice cap (3,499 m a.s.l.), which, despite ongoing surface mass loss, preserved a 6000-year-old record within just ∼10 m of ice depth. Methods Building on earlier research, this study provides an expanded chemical dataset of the upper 8.5 m of the 9.95 m ice core drilled in 2019 (core 2), now including 18 trace elements (Li, V, Cr, Mn, Co, Ni, Cu, Zn, As, Rb, Sr, Ag, Cd, Ba, Tl, Pb, Bi, U), carboxylic and dicarboxylic acids, and a deepened discussion on ionic compounds, which refines the already published record. To differentiate between natural contributions and anthropogenic sources, a Positive Matrix Factorisation analysis was applied to the full dataset. This analysis was further supported by Enrichment Factors calculations, which helped to discriminate between crustal and non-crustal sources. Results Thanks to the novel age-depth scale obtained with 39 Ar dating, in addition to previous 14 C ages, the glacier’s age-depth model was further refined, revealing that the glacier surface formed approximately <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1"> <mml:mrow> <mml:msubsup> <mml:mn>371</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>60</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>96</mml:mn> </mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> years before 2019, while tying the prominent peak in chemistry found at 640 cm depth to about 891 years before 2019. Further insights on this horizon came from the comparison between the levoglucosan record, measured within the WSS ice core, and the micro-charcoal data available for the nearby Schwarzboden mire. Discussion This study underscores the exceptional value of the WSS glacier as a long-term archive of pre-industrial pollution. Alarmingly, approximately 4.5 m of ice have been lost as of 2025, accelerating the disappearance of this archive. With industrial-era layers already lost due to ice mass reduction and projections showing 30% of Ötztal glaciers could vanish by 2030, preserving and studying these records appears increasingly urgent.