Determination of phospholipid fatty acid structures and stable carbon isotope compositions of deep-sea sediments of the Northwest Pacific, ODP Site 1179

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doi: 10.1016/j.marchem.2005.10.001
Author(s): Mills, Christopher T.; Dias, Robert F.; Graham, Dennis; Mandernack, Kevin W.
Author Affiliation(s): Primary:
Colorado School of Mines, Department of Chemistry and Geochemistry, Golden, CO, United States
Other:
Old Dominion University, United States
Texas A&M University, United States
Volume Title: Marine Chemistry
Source: Marine Chemistry, 98(2-4), p.197-209. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0304-4203 CODEN: MRCHBD
Note: In English. 75 refs.; illus., incl. 4 tables
Summary: Sediment samples ranging from 0.05 to 278 m below sea floor (mbsf) at a Northwest Pacific deep-water (5564 mbsl) site (ODP Leg 191, Site 1179) were analyzed for phospholipid fatty acids (PLFAs). Total PLFA concentrations decreased by a factor of three over the first meter of sediment and then decreased at a slower rate to approximately 30 mbsf. The sharp decrease over the first meter corresponds to the depth of nitrate and Mn(IV) reduction as indicated by pore water chemistry. PLFA-based cell numbers at site 1179 had a similar depth profile as that for Acridine orange direct cell counts previously made on ODP site 1149 sediments which have a similar water depth and lithology. The mole percentage of straight chain saturated PLFAs increases with depth, with a large shift between the 0.95 and 3.95 mbsf samples. PLFA stable carbon isotope ratios were determined for sediments from 0.05 to 4.53 mbsf and showed a general trend toward more depleted δ13C values with depth. Both of these observations may indicate a shift in the bacterial community with depth across the different redox zones inferred from pore water chemistry data. The PLFA 10me16:0, which has been attributed to the bacterial genera Desulfobacter in many marine sediments, showed the greatest isotopic depletion, decreasing from -20 to -35ppm over the first meter of sediment. Pore water chemistry suggested that sulfate reduction was absent or minimal over this same sediment interval. However, 10me16:0 has been shown to be produced by recently discovered anaerobic ammonium oxidizing (anammox) bacteria which are known chemoautotrophs. The increasing depletion in δ13C of 10me16:0 with the unusually lower concentration of ammonium and linear decrease of nitrate concentration is consistent with a scenario of anammox bacteria mediating the oxidation of ammonium via nitrite, an intermediate of nitrate reduction. Abstract Copyright (2006) Elsevier, B.V.
Year of Publication: 2006
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 07 Marine Geology and Oceanography; Ammonium ion; Bacteria; C-13/C-12; Carbon; Deep-sea environment; Desulfobacter; Experimental studies; Fatty acids; Gas chromatograms; Geochemistry; Hydrochemistry; Isotope ratios; Isotopes; Leg 191; Lipids; Marine environment; Marine sediments; Microorganisms; North Pacific; Northwest Pacific; ODP Site 1179; Ocean Drilling Program; Organic acids; Organic compounds; Oxidation; Pacific Ocean; Phospholipids; Phosphorus; Pore water; Sediments; Shatsky Rise; Stable isotopes; Sulfate ion; West Pacific
Coordinates: N410400 N410500 E1595800 E1595700
Record ID: 2007060880
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands