2024-03-28T13:23:46Z
https://tsukuba.repo.nii.ac.jp/oai
oai:tsukuba.repo.nii.ac.jp:00054795
2022-04-27T09:29:06Z
160:2593
160:7790
3:62:5297:5314
Validation of carbon isotope fractionation in algal lipids as a pCO2 proxy using a natural CO2 seep (Shikine Island, Japan)
アゴスティーニ, シルバン
アゴスティーニ, シルバン
AGOSTINI, Sylvain
ハーベイ, ベンジャミン ポール
ハーベイ , ベンジャミン ポール
HARVEY, Benjamin Paul
Witkowski, Caitlyn R.
van der Meer, Marcel T. J.
Sinninghe Damsté, Jaap S.
Schouten, Stefan
© Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License.
Carbon dioxide concentrations in the atmosphere play an integral role in many Earth system dynamics, including its influence on global temperature. The past can provide insights into these dynamics, but unfortunately reconstructing long-term trends of atmospheric carbon dioxide (expressed in partial pressure; pCO2) remains a challenge in paleoclimatology. One promising approach for reconstructing past pCO2 utilizes the isotopic fractionation associated with CO2 fixation during photosynthesis into organic matter (εp). Previous studies have focused primarily on testing estimates of εp derived from the δ13C of species-specific alkenone compounds in laboratory cultures and mesocosm experiments. Here, we analyze εp derived from the δ13C of more general algal biomarkers, i.e., compounds derived from a multitude of species from sites near a CO2 seep off the coast of Shikine Island (Japan), a natural environment with CO2 concentrations ranging from ambient (ca. 310 µatm) to elevated (ca. 770 µatm) pCO2. We observed strong, consistent δ13C shifts in several algal biomarkers from a variety of sample matrices over the steep CO2 gradient. Of the three general algal biomarkers explored here, namely loliolide, phytol, and cholesterol, εp positively correlates with pCO2, in agreement with εp theory and previous culture studies. pCO2 reconstructed from the εp of general algal biomarkers show the same trends throughout, as well as the correct control values, but with lower absolute reconstructed values than the measured values at the elevated pCO2 sites. Our results show that naturally occurring CO2 seeps may provide useful testing grounds for pCO2 proxies and that general algal biomarkers show promise for reconstructing past pCO2.
Copernicus Publications on behalf of the European Geosciences Union
2019-11
eng
journal article
http://hdl.handle.net/2241/00160204
https://tsukuba.repo.nii.ac.jp/records/54795
10.5194/bg-16-4451-2019
1726-4189
Biogeosciences
16
22
4451
4461
https://tsukuba.repo.nii.ac.jp/record/54795/files/Bgs_16-4451.pdf
application/pdf
1.0 MB
2020-06-25