Sea ice is an essential component in polar regions and plays an important role in global climate changes. Knowing sea-ice variabilities on long-term time scales is critical to understand the rapid sea-ice decline in recent decades and to predict future Arctic changes. In this study, a suite of biomarkers including highly branched isoprenoids (IP25 and HBI III (Z)) and sterols (brassicasterol and dinosterol) were measured in 55 surface sediments from the Bering-Chukchi Sea to central Arctic Ocean transect. PIP25 indices were calculated with sea-ice biomarker IP25 and phytoplankton biomarkers (brassicasterol, dinosterol and HBI III (Z)). The new data were combined with published data (n = 875) to complete the pan-Arctic dataset of biomarkers (n = 1062) in surface sediments. The compiled extended total data in general support previous pan-Arctic PIP25 studies and by this the reliability of the PIP25 approach for (paleo) sea-ice reconstructions. Furthermore, this study provides an extended basis for semi-quantitative paleo-sea-ice reconstruction in different regions of the Arctic Ocean. Phytoplankton biomarkers HBI III (Z) display highest values near the winter sea ice (WSI) edge in the pan-Arctic, reflecting the ice-edge conditions. PIIIIP25 show significant correlations with satellite spring/summer and autumn sea-ice concentration in the Pacific Sector of the pan-Arctic dataset (Bering-Chukchi Sea shelves, Chukchi Borderland and Canada Basin), and with spring/autumn sea-ice concentration in the Atlantic sector of the pan-Arctic dataset (Fram Strait, East Greenland shelf and Barents Sea). PIIIIP25 index seems to be reliable to reconstruct the paleo-sea-ice conditions in the Pan-Arctic, as well as PBIP25 and PDIP25 (using brassicasterol and dinosterol as phytoplankton biomarker, respectively). Furthermore, regional calibrations of comprehensive biomarker and PIP25 datasets against known sea-ice conditions would add further confidence in their application for paleo-sea-ice reconstruction. Based on our extended HBI III dataset we did not find that the HBI TR25 index was a reliable proxy for phytoplankton spring blooms on pan-Arctic scales. Certainly, deciphering the origin of certain biomarkers (e.g. HBI III (Z) and (E)) is still crucial for their application in further validation of PIP25 and TR25 indices application.

中文翻译：

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来自白令-楚科奇海表面沉积物的新海冰生物标志物数据及其对泛北极基于代理的海冰重建的意义


海冰是极地地区的重要组成部分，在全球气候变化中起着重要作用。了解长期时间尺度上的海冰变化对于了解近几十年来海冰的快速减少和预测未来的北极变化至关重要。在这项研究中，在从白令-楚科奇海到北冰洋中部横断面的 55 个表层沉积物中测量了一套生物标志物，包括高度支化的异戊二烯类物质（IP25 和 HBI III （Z））和甾醇（芸苔甾醇和地龙甾醇）。用海冰生物标志物 IP25 和浮游植物生物标志物 （芸苔属甾醇、地龙甾醇和 HBI III （Z）） 计算 PIP25 指数。将新数据与已发表的数据 （n = 875） 相结合，以完成表层沉积物中生物标志物 （n = 1062） 的泛北极数据集。汇编的扩展总数据总体上支持以前的泛北极 PIP25 研究，因此 PIP25 方法用于（古）海冰重建的可靠性。此外，本研究为北冰洋不同地区的半定量古海冰重建提供了扩展基础。浮游植物生物标志物 HBI III （Z） 在泛北极冬季海冰 （WSI） 边缘附近显示最高值，反映了冰边缘条件。PIIIIP25显示与泛北极数据集太平洋部分（白令-楚科奇海陆架、楚科奇边境和加拿大盆地）的卫星春/夏和秋季海冰浓度以及泛北极数据集大西洋部分（弗拉姆海峡、东格陵兰大陆架和巴伦支海）的春季/秋季海冰浓度呈显著相关性。 PIIIIP25指数似乎可以可靠地重建泛北极的古海冰条件，以及 PBIP25 和 PDIP25 （分别使用芸苔属甾醇和甲甾醇作为浮游植物生物标志物）。此外，针对已知海冰条件对综合生物标志物和 PIP25 数据集进行区域校准将进一步增加其在古海冰重建中的应用的信心。根据我们扩展的 HBI III 数据集，我们没有发现 HBI TR25 指数是泛北极尺度上浮游植物春季水华的可靠代表。当然，破译某些生物标志物（例如 HBI III （Z） 和 （E））的来源对于它们在进一步验证 PIP25 和 TR25 指数应用中的应用仍然至关重要。