Project

Back to overview

Radiocarbon dating of glacier ice

Applicant Schwikowski Margit
Number 126515
Funding scheme Project funding (Div. I-III)
Research institution Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Climatology. Atmospherical Chemistry, Aeronomy
Start/End 01.01.2010 - 31.12.2012
Approved amount 172'482.00
Show all

All Disciplines (2)

Discipline
Climatology. Atmospherical Chemistry, Aeronomy
Hydrology, Limnology, Glaciology

Keywords (7)

Radiocarbon; Dating; Glacier ice; Total organic carbon; Dissolved organic carbon; ice cores; natural archives

Lay Summary (English)

Lead
Lay summary
LeadA new radiocarbon dating method for glacier ice will be developed to provide complementary age information for the time period 15'000-500 years before present. IntroductionHigh-alpine ice cores from mid- and low-latitude glaciers and ice caps provide regional climate signals. To interpret the information contained in natural climate archives requires a precise chronology. For high-alpine ice cores there is a lack of an appropriate dating tool for the lowermost section since counting of annual layers is in the best case limited to a couple of centuries and is not suitable for the oldest and deepest ice. For these timescales, radiocarbon analysis can provide an absolute date. Recently a novel radiocarbon method has been developed by our group, using carbonaceous aerosols contained in the ice for radiocarbon dating. Carbonaceous particles are a major component of naturally occurring aerosols that are emitted ubiquitously or formed in the atmosphere and transported to potential ice core sites. The method is operational and may in principle be valuable for any ice body, that accumulated enough contemporary carbonaceous particles in the past and that remained undisturbed since then.Aims of the projectIn order to improve the skill of the radiocarbon dating method for broader application, we want to test the prospect of using total organic carbon (TOC) or water-soluble organic carbon (WSOC). TOC or WSOC represent the majority of carbon-containing compounds in ice and are therefore the most obvious carbon fraction for dating purposes. Using these major carbon fractions will increase the sensitivity and precision and will thus allow wider application to ice samples with generally lower carbon content, for example from polar regions, or to smaller sized samples. To achieve this goal a technique for extracting 14CO2 from the TOC or WSOC fraction of snow and ice will be developed and validated through analysis of well dated ice from existing ice cores.ImplicationsThis innovative radiocarbon method is thought to have major implications for dating non-polar and polar ice cores in the future, as it provides complementary age information for the time period 15'000-500 years BP which is not accessible with common dating techniques.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
Carbonaceous particles reveal that Late Holocene dust causes the dark region in the western ablation zone of the Greenland ice sheet
Wientjes IGM, van de Wal RSW, Schwikowski M, Zapf A, Fahrni S, Wacker L (2012), Carbonaceous particles reveal that Late Holocene dust causes the dark region in the western ablation zone of the Greenland ice sheet, in JOURNAL OF GLACIOLOGY, 58(210), 787-794.

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
IPICS First Open Science Conference 01.10.2012 Presquile de Gians, France
4th EuCheMS Chemistry Congress 26.08.2012 Prague, Czech Republic
9th Swiss Geoscience Meeting 11.11.2011 ETH Zurich, Switzerland
9th NCCR Climate Summer School 29.08.2011 Grindelwald


Communication with the public

Communication Title Media Place Year
Media relations: print media, online media Small Talk «Die Eisproben haben wir in ein Spital gebracht» Tages-Anzeiger German-speaking Switzerland 21.04.2012

Associated projects

Number Title Start Funding scheme
133817 Environmental Analysis and Dating with Radiocarbon using MICADAS 01.12.2010 R'EQUIP
144388 Radiocarbon dating of ice from a Kilimanjaro plateau glacier 01.01.2013 Project funding (Div. I-III)
144388 Radiocarbon dating of ice from a Kilimanjaro plateau glacier 01.01.2013 Project funding (Div. I-III)

Abstract

High-alpine ice cores from mid- and low-latitude glaciers and ice caps provide regional climate signals in areas inhabited by the majority of the world’s population. To interpret the information contained in natural climate archives requires a precise chronology. For high-alpine ice cores there is a lack of an appropriate dating tool for the lowermost section since strong ice flow induced layer thinning limits counting of annual layers in the best case to a couple of centuries and is not suitable for the oldest and deepest ice. Glacier flow is dominated by the small-scale geometry of bedrock, resulting in a strongly non-linear depth-age relationship over time, which cannot be fully resolved using physical ice flow models. For these timescales, radiocarbon analysis can provide an absolute date. Radiocarbon dating has been successfully applied to ice cores, when sufficient wood fragments or insects were found. However, this has rarely been the case - a fact limiting the wider application of this technique. Recently a novel radiocarbon method has been developed by our group, using carbonaceous aerosols contained in the ice for dating. Carbonaceous particles are a major component of naturally occurring aerosols that are emitted ubiquitously or formed in the atmosphere and transported to potential ice core sites. Application to ice cores from Illimani (Andes) and Colle Gnifetti (Alps) revealed that their ages cover a time span from 1,000 to more than 10,000 years. The method is operational and may in principle be valuable for any ice body, that accumulated enough contemporary carbonaceous particles in the past and that remained undisturbed since then. However, samples require at least 10 ?g carbon to be dated properly, since precision and accuracy are strongly controlled by the required blank correction. Thus 14C dating of carbonaceous particles in polar ice cores currently has less potential. Even in ice cores from high-alpine glaciers, a number of samples have carbon masses in this critical range. This is particularly unsatisfying since technical developments in AMS technologies nowadays allow samples with as little as 3 microgram C to be measured.However, water-insoluble carbonaceous particles form only a minor part of the carbon-containing matter in snow and ice. They were chosen for the first attempts of radiocarbon dating using carbon-containing chemical impurities in ice, since a procedure for radiocarbon analysis of aerosol samples existed. In order to improve the skill of the radiocarbon dating method for broader application, there is the prospect of using total organic carbon (TOC) or water-soluble organic carbon (WSOC). TOC or WSOC represent the majority of carbon-containing compounds in ice and are therefore the most obvious carbon fraction for dating purposes. Since both fractions consist of “reactive” molecules with relatively short lifetimes in the atmosphere, it can be assumed that they contain a contemporary 14C, suitable for dating. This proposal therefore seeks funding to develop a new radiocarbon based dating method for glacier ice using the major carbon fractions TOC and WSOC present in snow and ice. Using these major carbon fractions will increase the sensitivity and precision (better signal to blank ratio) and will thus allow wider application to ice samples with generally lower carbon content, for example from polar regions, or to smaller sized samples. To achieve this goal a technique for extracting 14CO2 from the TOC or WSOC fraction of snow and ice will be developed and vali-dated through analysis of well dated ice from existing ice cores. The novel radiocarbon method will then be used for dating of ice samples from Greenland, Svalbard, and Antarctica. This innovative radiocarbon method is thought to have major implications for dating non-polar and polar ice cores in the future, as it provides complementary age information for the time period 15’000-500 years BP which is not accessible with common dating techniques.
-