Bromine enrichment signal in Svalbard shallow cores reflects changes of seasonal sea ice variability

Description Bromine enrichment (Brenr) has been widely used as a proxy for past sea ice reconstructions. In this study, three firn cores drilled on Holtedahlfonna (Svalbard) were analysed for trace elements. Excluding a single year data, a positive correlation was observed between Brenr and springtime sea ice variability in the potential source region during 2005-2016. Accounting for different sea ice ages, Brenr 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 Brenr signal over time. Finally, the negative correlation with the δ¹⁸O temperature proxy further supports the capability of Brenr to capture past climate-change-driven sea ice fluctuations. In this database sodium (Na) and bromine (Br) concentrations for the three shallow firn cores and annual snow pits are provided. For additional information contact [e-mail] Acknowledgments This work has been supported by the "Programma di Ricerca in Artico" (PRA; project no. PRA2019-0011, Sentinel), by the Svalbard Science Forum/Research Council of Norway through the Arctic Field Grant call (projects ASIHAD, ISSICOS, and BIOMASS), by the French Polar Institute (IPEV; Institut Polaire Français Paul-Émile Victor) science funding (programmes 399 and 1192), and by the Svalbard Strategic Grant (project C2S3, no. 257636; SnowNet no. 295779 and BC3D no. 283466). The project was also funded by the European Union's Horizon Europe Research and Innovation Programme through the project LIQUIDICE (Grant Number: 101184962) and by the Svalbard Environmental Protection Fund (Svalbards miljøvernfond) through the project Threaten - The Svalbard biogeochemical shift duRing the AnThropocENe (Ref. 22/71). Moreover, this project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no. 689443 via project iCUPE (Integrative and Comprehensive Understanding on Polar Environments). The University of Perugia's research cluster no. 5, "Climate, Energy, and Mobility" has also partially funded this research. In addition, CryoGrid simulations have been supported by the Nansen Legacy project (Research Council of Norway, Grant 276730) and SIOS-InfraNor (Research Council of Norway, Grant 269927). Finally, this research work was supported by a PNRR-funded (National Recovery and Resilience Plan) PhD scholarship in Polar Sciences at Ca' Foscari University of Venice, within the framework of the European Union - Next Generation EU, Mission 4 Component 1 (CUP H73C23000510006), pursuant to Ministerial Decree No. 118/2023.数据集说明 溴富集（Bromine enrichment, Brenr）已被广泛用作过去海冰重建的代用指标。本研究对斯瓦尔巴群岛霍尔特达勒冰盖（Holtedahlfonna）上钻取的3根粒雪芯开展了微量元素分析。在剔除单一年份数据后，2005—2016年间，溴富集指数与潜在源区春季海冰变异性呈现显著正相关。在考虑不同海冰年龄的影响后，溴富集信号仅与一年冰呈现显著相关，进一步证实了其在春季气相溴排放中的核心贡献。对浅粒雪芯中的钠（Sodium, Na）、溴（Bromine, Br）浓度与同期在同一地点采集的年度雪坑对应值进行对比后发现，元素再分配过程对二者的影响具有一致性，使得溴富集信号随时间整体保持稳定。最后，溴富集指数与δ¹⁸O温度代用指标呈负相关，进一步支撑了溴富集指数能够捕捉气候变化驱动的过去海冰波动这一能力。 本数据库提供了3根浅粒雪芯及年度雪坑中的钠、溴浓度数据。 如需获取更多信息，请联系[e-mail] 致谢 本研究得到了“北极研究计划”（Programma di Ricerca in Artico, PRA；项目编号PRA2019-0011，项目名Sentinel）、斯瓦尔巴科学论坛/挪威研究理事会北极野外资助项目（ASIHAD、ISSICOS及BIOMASS）、法国极地研究所（IPEV, Institut Polaire Français Paul-Émile Victor）资助的科研计划（编号399与1192），以及斯瓦尔巴战略资助项目（C2S3项目编号257636、SnowNet项目编号295779及BC3D项目编号283466）的支持。本项目同时获得欧盟“地平线欧洲”研究与创新计划资助（项目编号101184962，项目名LIQUIDICE），以及斯瓦尔巴环境保护基金资助的《人类世时期斯瓦尔巴群岛生物地球化学转变》（Threaten，编号22/71）项目。此外，本项目还依托欧盟“地平线2020”研究与创新计划资助协议号689443，通过iCUPE项目（极地环境综合全面研究计划）获得经费支持。佩鲁贾大学第5研究集群“气候、能源与出行”也为本研究提供了部分经费。CryoGrid模拟工作得到了“南森遗产”项目（挪威研究理事会，资助编号276730）及SIOS-InfraNor项目（挪威研究理事会，资助编号269927）的支持。最后，本研究工作获得了意大利威尼斯卡福斯卡里大学由国家恢复与韧性计划（PNRR）资助的极地科学博士奖学金支持，该奖学金隶属于欧盟“下一代欧盟”任务4组件1（项目编号CUP H73C23000510006），依据2023年第118号部长令设立。