Bromine Enrichment Signal in Svalbard Shallow Cores Reflects Changes of Seasonal Sea Ice Variability

Bromine enrichment (B⁢re⁢n⁢r) has been widely used as a proxy for past sea ice reconstructions. In this study, three firn cores drilled on Holtedahlfonna (Svalbard) were analyzed for trace elements. Excluding a single year data, a positive correlation was observed between B⁢re⁢n⁢r and springtime sea ice variability in the potential source region during 2005-2016. Accounting for different sea ice ages, B⁢re⁢n⁢r signal resulted significantly correlated only with first-year sea ice, reinforcing its role as a major contributor to springtime gas-phase bromine emissions. Comparisons between Na and Br concentrations in shallow cores and temporally corresponding values in annual snow pits collected at the same site reveal that elemental reallocation similarly affects both chemicals, resulting in a generally stable B⁢re⁢n⁢r signal over time. Finally, the negative correlation with the δ18O temperature proxy further supports the capability of B⁢re⁢n⁢r to capture past climate-change-driven sea ice fluctuations.