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Isotopic compositions of lipid biomarker compounds in estuarine plants and surface sediments
Author(s) -
Canuel Elizabeth A.,
Freeman Katherine H.,
Wakeham Stuart G.
Publication year - 1997
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.1997.42.7.1570
Subject(s) - organic matter , spartina alterniflora , sedimentary organic matter , environmental chemistry , macrophyte , total organic carbon , δ13c , sediment , environmental science , oceanography , geology , chemistry , ecology , stable isotope ratio , biology , wetland , marsh , paleontology , physics , quantum mechanics
We examined the isotopic compositions of fatty acids, sterols, and hydrocarbons isolated from three coastal macrophytes ( Zostera marina, Spartina alterniflora, and Juncus roemerianus ) in order to investigate the relative contribution of these vascular plants as sources of organic matter in coastal sediments such as Cape Lookout Bight, North Carolina. On average, lipid biomarker compounds extracted from the plants were depleted in 13 C by 3–5‰ relative to δ 13 C total organic carbon (TOC). However, individual compounds within each lipid class varied by up to 5.6‰. Trends in the isotopic compositions of lipids were consistent with δ 13 C TOC ; compounds obtained from Z. marina were the most enriched in 13 C and those from J. roemerianus were the most depleted. The range in isotopic abundances and molecular compositions of the sediments was greater than that obtained from the plants, indicating that additional, presently unidentified sources of organic matter contribute to the Cape Lookout Bight sediments. Similarity between the signatures for suspended particulate matter and the sediments indicates that much of the sedimentary organic matter is derived from algal and bacterial sources. Bacterial sources of organic matter are likely greater during summer/early fall, and incorporation of 13 C‐enriched bacterial biomass may contribute to observed seasonal shifts in δ 13 C TOC in the surficial sediments.