Abstract
Ratios of glycerol dialkyl glycerol tetraethers (GDGT), which are membrane lipids of bacteria and archaea, are at the base of several paleoenvironmental proxies. They are frequently applied to soils as well as lake- and marine sediments to generate records of past temperature and soil pH. To derive meaningful environmental information from these reconstructions, high analytical reproducibility is required. Based on submitted results by 39 laboratories from across the world, which employ a diverse range of analytical and quantification methods, we explored the reproducibility of brGDGT-based proxies (MBT′5ME, IR, and #ringstetra) measured on four soil samples and four soil lipid extracts. Correct identification and integration of 5- and 6-methyl brGDGTs is a prerequisite for the robust calculation of proxy values, but this can be challenging as indicated by the large inter-interlaboratory variation. The exclusion of statistical outliers improves the reproducibility, where the remaining uncertainty translates into a temperature offset from median proxy values of 0.3–0.9°C and a pH offset of 0.05–0.3. There is no apparent systematic impact of the extraction method and sample preparation steps on the brGDGT ratios. Although reported GDGT concentrations are generally consistent within laboratories, they vary greatly between laboratories. This large variability in brGDGT quantification may relate to variations in ionization efficiency or specific mass spectrometer settings possibly impacting the response of brGDGTs masses relative to that of the internal standard used. While ratio values of GDGT are generally comparable, quantities can currently not be compared between laboratories.
DOI Link
Publication Date
2024-07-19
Publication Title
Geochemistry, Geophysics, Geosystems
Volume
25
Issue
7
ISSN
1525-2027
Acceptance Date
2024-06-26
Deposit Date
2024-07-26
Funding
The authors thank two reviewers, Sarah Feakins and Yunping Xu, for their constructive comments. In addition, we would like to thank Jorien Vonk (VU, The Netherlands) for providing Soil A from Canada, Frank Hagedorn (WSL, Switzerland) for Soil B from Switzerland, Sebastian D\u00F6tterl (ETH, Switzerland) for Soil C from Rwanda, and Christoph H\u00E4ggi (ETH, Switzerland) for Soil D from Brazil. Adele Blatter (ETH, Switzerland) has helped with the preparation of soil samples. This study received funding from NWO\u2010Vidi Grant (192.074) awarded to FP and PRIMA (PR00P2_179783) and SNSF Starting Grant (TMSGI2_211319) grants from SNSF to CDJ. AS thanks the European Research Council for funding Consolidator Grant 771497 under Horizon 2020 program. SN, BD and TA thank GNS Science and Victoria University of Wellington for their ongoing support of the GNS/VUW Organic Geochemistry Laboratory, and the New Zealand Ministry of Business, Innovation and Employment (MBIE) in the framework of the Global Change Through Time research program (contract C05X1702). The authors thank two reviewers, Sarah Feakins and Yunping Xu, for their constructive comments. In addition, we would like to thank Jorien Vonk (VU, The Netherlands) for providing Soil A from Canada, Frank Hagedorn (WSL, Switzerland) for Soil B from Switzerland, Sebastian D\u00F6tterl (ETH, Switzerland) for Soil C from Rwanda, and Christoph H\u00E4ggi (ETH, Switzerland) for Soil D from Brazil. Adele Blatter (ETH, Switzerland) has helped with the preparation of soil samples. This study received funding from NWO-Vidi Grant (192.074) awarded to FP and PRIMA (PR00P2_179783) and SNSF Starting Grant (TMSGI2_211319) grants from SNSF to CDJ. AS thanks the European Research Council for funding Consolidator Grant 771497 under Horizon 2020 program. SN, BD and TA thank GNS Science and Victoria University of Wellington for their ongoing support of the GNS/VUW Organic Geochemistry Laboratory, and the New Zealand Ministry of Business, Innovation and Employment (MBIE) in the framework of the Global Change Through Time research program (contract C05X1702).
Additional Links
Keywords
GDGT, interlaboratory comparison, round robin
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
BrGDGTs Round Robin., De Jonge, C., Peterse, F., Nierop, K., Blattmann, T., Alexandre, M., Ansanay-Alex, S., Austin, T., Babin, M., Bard, E., Bauersachs, T., Blewett, J., Boehman, B., Castañeda, I., Chen, J., Conti, M., Contreras, S., Cordes, J., Davtian, N., van Dongen, B., Duncan, B., Elling, F., Galy, V., Gao, S., Hefter, J., Hinrichs, K., Helling, M., Hoorweg, M., Hopmans, E., Huguet, A., Jia, G., Karger, C., Keely, B., Kusch, S., Li, H., Liang, J., Lipp, J., Liu, W., Lu, H., Mangelsdorf, K., Manners, H., Martinez Garcia, A., Menot, G., Mollenhauer, G., Naafs, B., Naeher, S., O'Connor, L., Pearce, E., & Pearson, A. (2024) 'Interlaboratory Comparison of Branched GDGT Temperature and pH Proxies Using Soils and Lipid Extracts', Geochemistry, Geophysics, Geosystems, 25(7). Available at: 10.1029/2024GC011583
