气候变化领域集成服务门户(CCPortal): Radiocarbon dating of glacier ice: Overview, optimisation, validation and potential

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DOI	10.5194/tc-10-3091-2016
	Radiocarbon dating of glacier ice: Overview, optimisation, validation and potential
	Uglietti C.; Zapf A.; Jenk T.M.; Sigl M.; Szidat S.; Salazar G.; Schwikowski M.
发表日期	2016
ISSN	19940416
卷号	10 期号:6
英文摘要	High-altitude glaciers and ice caps from midlatitudes and tropical regions contain valuable signals of past climatic and environmental conditions as well as human activities, but for a meaningful interpretation this information needs to be placed in a precise chronological context. For dating the upper part of ice cores from such sites, several relatively precise methods exist, but they fail in the older and deeper parts, where plastic deformation of the ice results in strong annual layer thinning and a non-linear age-depth relationship. If sufficient organic matter such as plant, wood or insect fragments were found, radiocarbon (14C) analysis would have thus been the only option for a direct and absolute dating of deeper ice core sections. However such fragments are rarely found and, even then, they would not be very likely to occur at the desired depth and resolution. About 10 years ago, a new, complementary dating tool was therefore introduced by our group. It is based on extracting the μg-amounts of the water-insoluble organic carbon (WIOC) fraction of carbonaceous aerosols embedded in the ice matrix for subsequent 14C dating. Since then this new approach has been improved considerably by reducing the measurement time and improving the overall precision. Samples with ∼ 10 μg WIOC mass can now be dated with reasonable uncertainty of around 10-20 % (variable depending on sample age). This requires about 300 to 800 g of ice for WIOC concentrations typically found in midlatitude and low-latitude glacier ice. Dating polar ice with satisfactory age precision is still not possible since WIOC concentrations are around 1 order of magnitude lower. The accuracy of the WIOC 14C method was validated by applying it to independently dated ice. With this method, the deepest parts of the ice cores from Colle Gnifetti and the Mt Ortles glacier in the European Alps, Illimani glacier in the Bolivian Andes, Tsambagarav ice cap in the Mongolian Altai, and Belukha glacier in the Siberian Altai have been dated. In all cases a strong annual layer thinning towards the bedrock was observed and the oldest ages obtained were in the range of 10 000 years. WIOC 14C dating was not only crucial for interpretation of the embedded environmental and climatic histories, but additionally gave a better insight into glacier flow dynamics close to the bedrock and past glacier coverage. For this the availability of multiple dating points in the deepest parts was essential, which is the strength of the presented WIOC 14C dating method, allowing determination of absolute ages from principally every piece of ice. © Author(s) 2016.
学科领域	accuracy assessment; aerosol; age determination; carbon isotope; glacier dynamics; glacier flow; ice core; ice thickness; optimization; organic matter; radiocarbon dating; uncertainty analysis; Alps; Altai Mountains; Altay [Russian Federation]; Andes; Belukha Glacier; Bolivia; Bolivia; Colle Gnifetti Glacier; Illimani; Italy; La Paz [Bolivia]; Mongolia; Ortles; Russian Federation; Hexapoda
语种	英语
scopus关键词	accuracy assessment; aerosol; age determination; carbon isotope; glacier dynamics; glacier flow; ice core; ice thickness; optimization; organic matter; radiocarbon dating; uncertainty analysis; Alps; Altai Mountains; Altay [Russian Federation]; Andes; Belukha Glacier; Bolivia; Bolivia; Colle Gnifetti Glacier; Illimani; Italy; La Paz [Bolivia]; Mongolia; Ortles; Russian Federation; Hexapoda
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/119525
作者单位	Laboratory of Environmental Chemistry, Paul Scherrer Institute, Villigen PSI, 5232, Switzerland; Department of Chemistry and Biochemistry, University of Bern, Bern, 3012, Switzerland; Oeschger Centre for Climate Change Research, University of Bern, Bern, 3012, Switzerland
推荐引用方式 GB/T 7714	Uglietti C.,Zapf A.,Jenk T.M.,et al. Radiocarbon dating of glacier ice: Overview, optimisation, validation and potential[J],2016,10(6).
APA	Uglietti C..,Zapf A..,Jenk T.M..,Sigl M..,Szidat S..,...&Schwikowski M..(2016).Radiocarbon dating of glacier ice: Overview, optimisation, validation and potential.Cryosphere,10(6).
MLA	Uglietti C.,et al."Radiocarbon dating of glacier ice: Overview, optimisation, validation and potential".Cryosphere 10.6(2016).