A critical review of marine sedimentaryδ¹³C_org‐<i>p</i>CO₂ estimates: New palaeorecords from the South China Sea and a revisit of other low‐latitude δ¹³C_org‐<i>p</i>CO₂ records

• Markus Kienast

• Stephen E. Calvert

• Carles Pelejero

• Joan O. Grimalt

抄録

In an attempt to understand better the local biogeochemistry of the South China Sea (SCS) and to unravel the contribution of this marginal low‐latitude basin to changes in atmospheric CO 2 concentrations, we analyzed the carbon isotopic composition of organic matter (δ 13 C org ) in four sediment cores from throughout the SCS covering the last 220 kyr. Higher values (around −19.5 to −20.5‰) mark glacial stages, while lower values (around −21 to −22.5‰) are characteristic of interglacials. Following well established procedures, the δ 13 C org records are converted to local p CO 2 estimates. On the basis of these and other low‐latitude δ 13 C org − p CO 2 estimates from the literature, we present a critical evaluation of the use of δ 13 C of bulk sedimentary organic matter to hindcast past changes in local CO 2 (aq). Three crucial pitfalls are identified. (1) Given the present inability to quantify precisely the time‐varying amount of terrigenous C org input to marine sediments, absolute values of p CO 2 estimates based on bulk sedimentary C org are questionable. (2) None of the low‐latitude sedimentary δ 13 C org − p CO 2 records shows the expected correlation between temporal changes in upwelling intensity and CO 2 estimates, most likely due to the antagonistic influences of CO 2 (aq) and phytoplankton growth rate on δ 13 C org . (3) A detailed comparison of marine δ 13 C org − p CO 2 records with the Vostok CO 2 record reveals significant differences in phasing, specifically at the end of the last deglaciation and during the oxygen isotope stage 5/4 transition. However, in areas where equilibrium between oceanic and atmospheric CO 2 occurs, for example the SCS and the Mediterranean, the timing of changes in δ 13 C org should agree with the CO 2 record from ice cores if δ 13 C org is a reliable proxy for changes in CO 2 (aq). Taken together, the compilation of records presented here cautions the use of δ 13 C org as an unambiguous tracer of dissolved molecular CO 2 in the surface ocean and calls for a re‐evaluation of the role of the low‐latitude ocean on temporal changes in atmospheric CO 2 .

収録刊行物

• Global Biogeochemical Cycles

  Global Biogeochemical Cycles 15 (1), 113-127, 2001-03

  American Geophysical Union (AGU)

キーワード

• Atmospheric Science
• General Environmental Science
• Environmental Chemistry
• Global and Planetary Change

詳細情報

• CRID: 1360011145525235456
• NII論文ID: 30013378396
• DOI: 10.1029/2000gb001285
• ISSN: 19449224
• ISSN: 08866236
• Web Site: https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1029%2F2000GB001285
• Web Site: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2000GB001285
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