A novel proxy for Arctic sea-ice

人们普遍认为极地海冰在全球气候变化中起着至关重要的作用。因此，海冰重建对于确定过去地质时期的气候演变具有至关重要的意义。虽然过去200年的海冰直接记录被认为是相当准确的（利用过去30年的卫星成像），但只有通过使用“代理”措施（海冰的化学、物理或生物指标）才能获得更广泛的记录。当前项目的主要目的是评估一些具有良好特征的有机化学品的使用情况，以作为过去海冰存在的代表。这些化学物质，即所谓的高支异戊二烯类化合物（hbi），具有许多特征，使它们成为具有吸引力的海冰替代物。首先，这种类型的hbi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与以前海冰的出现直接相关。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，它们的相对丰度应该使它们易于测量（一个标准操作程序已被确定为项目的输出），此外，具有高度的地质分辨率。这项调查的结果将与以前在北极沉积物中使用的代用物进行评估。该项目与理事会计划的其他方面配合得很好，显然与“极北”分类和“全球变化”ENRI都有100%的相关性。该项目物超所值，因为现有的岩心已经建立，所有必要的化学和分析要求都在普利茅斯大学的石油和环境地球化学小组内部进行。该项目还将受益于当地和国际上现有的额外工作人员专业知识

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