AUTHOR=Lee Jay , Yang Rick J. , Lin Hui-Ling , Chen Yi-Chi , Cai-Li Ren-Yi , Ren Haojia , Liu James T. TITLE=Sedimentary Anthropogenic Carbon Signals From the Western Pacific Margin for the Last Century JOURNAL=Frontiers in Earth Science VOLUME=9 YEAR=2022 URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2021.795519 DOI=10.3389/feart.2021.795519 ISSN=2296-6463 ABSTRACT=

The declining trend of the δ¹³C of tropical corals over the last century was about −0.01‰ year⁻¹, according to global coral records. The decrease was attributable to the significant input of anthropogenic CO₂ (¹³C Suess effect) to the atmosphere. Previous studies of δ¹³C in corals suggested that the signal of the anthropogenic carbon in the Pacific and Indian Oceans were weaker than that in the Atlantic Ocean. However, biases relating to environments in which corals grew caused concerns. To investigate the anthropogenic carbon signal in the Western Pacific, foraminiferal records in a suite of 13 box cores with good age control were obtained from the continental slope off southwestern Taiwan between 2004 and 2006. δ¹⁸O values of planktonic foraminifera (Globigerinoides sacculifer or so-called Trilobatus sacculifer) in collected cores were relatively stable at −2.5‰ to −2‰ in the last century, but foraminiferal δ¹³C had a gradual secular decline after the 1900s. The decline trend of δ¹³C began to intensify after the 1960s, and its rate was similar to that observed in the Atlantic. Similar decline trends of δ¹³C were also found in coral records at regions where the human activity is high (Liuqiu) and low (Dongsha). Our findings indicate that the anthropogenic carbon signal in the Western Pacific was not weaker than that recorded in the Atlantic, and the nearshore sediment can supplement the lack of δ¹³C records in corals, which are deficient when the environment is not suitable to grow.