Open AccessAnalysis of δ 18 O in tree rings: Wood‐cellulose comparison and method dependent sensitivity
Author(s) -
Borella Silvio,
Leuenberger Markus,
Saurer Matthias
Publication year - 1999
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/1999jd900298
Subject(s) - cellulose , pyrolysis , materials science , analytical chemistry (journal) , nickel , line (geometry) , sample (material) , sample preparation , chemistry , chromatography , organic chemistry , mathematics , metallurgy , geometry
During recent years, new on‐line methods in mass spectrometry have been developed for measuring δ 18 O in organic material. They allow a much higher sample throughput than off‐line methods with the result that sample preparation becomes the time‐limiting factor. Therefore we tested whether analysis of tree ring samples can be made on whole wood instead of pure cellulose, which until now was commonly used in almost all 18 O tree ring studies. Measurements with an on‐line method based on pyrolysis in an elemental analyzer show that the tree ring δ 18 O time series of wood and cellulose from an oak of the Swiss “Mittelland” are similar ( r 2 = 0.65). However, there are significant differences, and some climatic information may be lost if bulk wood is analyzed instead of cellulose. This can partly be balanced by an increased sample throughput, resulting in the averaging of more data. Further, we improved an off‐line method (pyrolysis in a nickel tube followed by catalytic CO to CO 2 conversion on nickel powder) by adding a CO 2 trap to enhance the CO to CO 2 conversion. The best reproducibility associated with this method is better than 0.1‰. We also found a strong memory effect linked with this method, causing a dampening of the signal of 30–40%. Therefore published climatic interpretation of δ 18 O data measured using similar methods may require revision.