Compound-Specific Radiocarbon Analysis of Organic Compounds from Mount Fuji Proximal Lake (Lake Kawaguchi) Sediment, Central Japan

• Published in: Radiocarbon Vol. 62; no. 2; pp. 439 - 451
• Main Authors: Yamamoto, Shinya, Miyairi, Yosuke, Yokoyama, Yusuke, Suga, Hisami, Ogawa, Nanako O, Ohkouchi, Naohiko
• Format: Journal Article
• Language: English
• Published: Tucson Cambridge University Press 01.04.2020
• Subjects: Biomarkers; Carbon; Chlorophyll; Chromatography; Fatty acids; Lakes; Organic compounds; Particle size; Pigments; Radiometric dating; Sediments; Surface water; Mount Fuji; Japan
• ISSN: 0033-8222; 1945-5755
• DOI: 10.1017/RDC.2019.158

ABSTRACT Differential sources of sedimentary organic compounds in a volcanic region were revealed by determining radiocarbon content (Δ 14 C) of organic compounds in surface sediments from Lake Kawaguchi, at the northern foot of Mount Fuji, central Japan. The Δ 14 C values of C 16 fatty acid (−124‰) and chlorophyll a (Chl a ) (−133‰) were similar to the Δ 14 C of dissolved inorganic carbon (DIC) in surface water (−117‰), suggesting that a significant portion of these compounds originated from modern primary producers with a reservoir age of ~1000 years. On the other hand, a large offset between the Δ 14 C values of Chl a (−133‰) and those of 13 2 , 17 3 -cyclopheophorbide- a -enol (−169‰) and pheophytin a (−179‰) suggested contributions from older pigments. In addition, the Δ 14 C of long-chain (C 24 , C 26 , and C 28 ) fatty acids (−183 to −75‰) showed a large offset from that of a plant leaf remain (0‰) within sediments, demonstrating that the long-chain fatty acids were affected by substantial contributions from pre-aged terrestrial materials. Overall, the sedimentary organic compounds gave 14 C ages older than the plant leaf fragment within sediments; however, the similarity between Δ 14 C of the C 16 fatty acid and DIC implies potential for applying compound-specific radiocarbon analysis as a dating tool in volcanic lake environments.