An improved method for delta 15 N measurements in ice cores

• Main Authors: Mani, F. S., Dennis, Paul, Sturges, W. T., Mulvaney, R., Leuenberger, M.
• Other Authors: School of Environmental Sciences Norwich, University of East Anglia Norwich (UEA), British Antarctic Survey (BAS), Natural Environment Research Council (NERC), Climate and Environmental Physics Bern (CEP), Physikalisches Institut Bern, Universität Bern / University of Bern (UNIBE)-Universität Bern / University of Bern (UNIBE)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2008
• Subjects: [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Antarctic; Antarc*; ice core
• Online Access: https://hal.science/hal-00298207; https://hal.science/hal-00298207/document; https://hal.science/hal-00298207/file/cpd-4-149-2008.pdf

International audience The use of isotopic ratios of nitrogen gas (? 15 N) trapped in ice cores as a paleothermometer to characterise abrupt climate changes is becoming a widespread technique. The versatility of the technique could be enhanced, for instance in quantifying small temperature changes during the last glacial period in Antarctic ice cores, by using high precision methods. In this paper, we outline a method for measuring ? 15 N to a precision of 0.006\permil (1?, n=9) from replicate ice core samples. The high precision results from removing oxygen, carbon dioxide and water vapour from the air extracted from ice cores. The advantage of the technique is that it does not involve correction for isobaric interference due to CO + ions. We also highlight the importance of oxygen removal from the sample, and how it influences ? 15 N measurements. The results show that a small amount of oxygen in the sample can be detrimental to achieving an optimum precision in ? 15 N measurements of atmospheric nitrogen trapped ice core samples.