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Radiocarbon analysis of neutral sugars in high‐molecular‐weight dissolved organic carbon: Implications for organic carbon cycling
Author(s) -
Repeta Daniel J.,
Aluwihare Lihini I.
Publication year - 2006
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2006.51.2.1045
Subject(s) - radiocarbon dating , dissolved organic carbon , chemistry , carbon fibers , environmental chemistry , carbon cycle , hydrolysis , sugar , dissolution , total organic carbon , acid hydrolysis , organic matter , geology , organic chemistry , ecology , biology , paleontology , materials science , ecosystem , composite number , composite material
We used compound‐specific natural‐abundance radiocarbon analyses of neutral sugars to study carbon cycling of high‐molecular‐weight (HMW) dissolved organic carbon (DOC) at two sites in the North Pacific Ocean. Sugars released from HMW DOC by acid hydrolysis were purified by high‐pressure liquid chromatography and analyzed for radiocarbon content via accelerator mass spectrometry. The seven most abundant sugars recovered from HMW DOC have similar radiocarbon values, supporting the hypothesis that these sugars are incorporated into a common family of polysaccharides. Neutral sugar Δ 14 C values from surface waters collected in 1999 and 2001 are 89 ± 13‰ and 57 ± 6‰, respectively; these values are much more enriched in radiocarbon than those found in previous studies that used operationally defined carbohydrate fractions. Radiocarbon values for HMW DOC neutral sugars are the same as, or only slightly depleted relative to, dissolved inorganic carbon (DIC), which is consistent with rapid cycling and a short (<3‐yr) residence time. In addition, the Δ 14 C value of neutral sugars at 600 m is 20‰ enriched relative to DIC Δ 14 C, suggesting that a fraction of dissolved neutral sugars at this depth are introduced by dissolution from large, rapidly sinking particles.