A novel proxy for Arctic sea-ice

人们普遍承认，极地海冰在全球气候变化中起着关键作用。因此，海冰重建在确定地质历史的气候演变方面应该是至关重要的。虽然人们认为过去200年来海冰的直接记录相当准确（过去30年的卫星成像），但只有通过使用“替代”措施（海冰的化学、物理或生物指标）才能获得更广泛的记录。目前项目的主要目的是评估使用一些具有良好特征的有机化学品作为过去海冰存在的替代品。这些化学物质，所谓的高度支化类异戊二烯（HBIs），具有许多特性，使他们有吸引力的海冰代理。首先，所提出的类型的HBIs是海冰硅藻所特有的，因此它们在极地沉积物中的存在可以直接与以前的海冰发生相关。其次，它们相对不易降解，这扩大了它们在地质记录中的用途。第三，它们的相对丰度应使它们易于测量（标准操作程序已被确定为该项目的一项产出），此外，具有高度的地质分辨率。这项调查的结果将根据以前在北极沉积物中使用的代理进行评估。该项目与理事会计划的其他方面非常吻合，显然与“北极”分类和“全球变化”ENRI都有100%的相关性。该项目是一个非常物有所值的项目，因为已经建立了对现有岩心的访问，所有必要的化学和分析要求都由普利茅斯大学石油和环境地球化学小组内部掌握。该项目还将受益于更多的当地和国际工作人员的专门知识

It is widely acknowledged that polar sea-ice plays a critical role in global climate change. As such, sea-ice reconstruction should be of paramount importance in establishing climatic evolution of the geological past. Although direct records of sea-ice are considered to be reasonably accurate over the last 200 years (with satellite imaging for the past 30 years), it is only through the use of 'proxy' measures (chemical, physical or biological indicators of sea-ice) that a more extended record is achievable. The main aim of the current project proposes to evaluate the use of some well characterised organic chemicals to serve as a proxy for the past presence of sea-ice. These chemicals, so-called highly branched isoprenoids (HBIs), possess a number of characteristics that make them attractive as sea-ice proxies. Firstly, HBIs of the type proposed are unique to sea-ice diatoms, so their presence in polar sediments can be directly correlated with the previous occurrence of sea-ice. Secondly, they are relatively resistant to degradation, which extends their usefulness in the geological record. Thirdly, their relative abundance should make them straightforward to measure (A Standard Operating Procedure has been identified as an output from the project) with, additionally, a high degree of geological resolution. The results of this investigation will be evaluated against previous proxies used in Arctic sediments. This project fits well with other aspects of the Council's programme and clearly has a 100% relevance to both the 'Polar North' classification and the 'Global Change' ENRI. The project represents excellent value for money, as access to existing cores has already been established, and all of the necessary chemical and analytical requirements are held in-house within the Petroleum and Environmental Geochemistry Group at the University of Plymouth. The project will also benefit from additional staff expertise available both locally and internationally