URLhttps://www.bco-dmo.org/dataset/815362
CreatedJune 15, 2020
ModifiedJuly 16, 2020
StateData not available yet

Processing Description

Spectral processing was completed by subtracting a line fit to the pre-edge region (281–283 eV), followed by an area normalization between 282 and 310 eV with the high-energy intensity kept constant (atomic normalization). The entire pre-edge region appeared linear; fitting and background subtraction was conducted over a smaller energy range due to the presence of oxygen harmonic peaks. All the data normalization was conducted in Igor Pro (WaveMetrics).

BCO-DMO Data Manager Processing Notes:
* exported data in xlsx file "Estes_NEXAFSstds_data.xlsx" to csv file
* added a conventional header with dataset name, PI name, version date
* modified parameter names to conform with BCO-DMO naming conventions
* blank values in this dataset are displayed as "nd" for "no data."  nd is the default missing data identifier in the BCO-DMO system.

Instruments

Instance Description

Bulk carbon synchrotron-based near edge x-ray fine structure (NEXAFS) spectroscopy was conducted on beamlines 8-2 and 10-1 at the Stanford Synchrotron Radiation Lightsource.

A spectrometer is an optical instrument used to measure properties of light over a specific portion of the electromagnetic spectrum.

Parameters

eV [eV]
Details
eV

incident energy

The amount of energy gained or lost by the charge of a single electron moving across an electric potential difference of one volt. One electronvolt equal to 1.602*10−19 joules.

Details
BSA
absorption values for protein (bovine serum albumin (BSA)). arbitrary units (normalized)

The fraction of radiant flux absorbed (at a specific wavelength).

phenylalanin [absorbance]
Details
phenylalanin
absorption values of phenylalanin. arbitrary units (normalized)

The fraction of radiant flux absorbed (at a specific wavelength).

leucine [absorbance]
Details
leucine
absorption values of leucine. arbitrary units (normalized)

The fraction of radiant flux absorbed (at a specific wavelength).

agarose [absorbance]
Details
agarose
absorption values of agarose. arbitrary units (normalized)

The fraction of radiant flux absorbed (at a specific wavelength).

alginate [absorbance]
Details
alginate
absorption values of alginate. arbitrary units (normalized)

The fraction of radiant flux absorbed (at a specific wavelength).

lipo [absorbance]
Details
lipo
absorption values of lipo. arbitrary units (normalized)

The fraction of radiant flux absorbed (at a specific wavelength).

phospholipid [absorbance]
Details
phospholipid
absorption values of phospholipid. arbitrary units (normalized)

The fraction of radiant flux absorbed (at a specific wavelength).

HMWDOM [absorbance]
Details
HMWDOM
absorption values of high molecular weight dissolved organic matter (HMWDOM). arbitrary units (normalized)

The fraction of radiant flux absorbed (at a specific wavelength).

humic acid [absorbance]
Details
humic acid
absorption values of humic acid. arbitrary units (normalized)

The fraction of radiant flux absorbed (at a specific wavelength).

Dataset Maintainers

NameAffiliationContact
Emily R. EstesTexas A&M University (TAMU)
Colleen M. HanselWoods Hole Oceanographic Institution (WHOI)
Amber YorkWoods Hole Oceanographic Institution (WHOI BCO-DMO)

BCO-DMO Project Info

Project TitleGeochemical controls on organic carbon quantity and quality in the deep subsurface
AcronymOrg C Sed II
URLhttps://www.bco-dmo.org/project/779216
CreatedOctober 15, 2019
ModifiedOctober 16, 2019
Project Description

Abstract from the C-DEBI project page:

Sediment underlying ocean gyres receives minimal input of fresh organic matter yet sustains a small but active heterotrophic microbial community. The concentration and composition of the organic carbon (OC) available to this deep biosphere however is unknown. We analyzed the content and composition of OC in pelagic sediment in order to identify mechanism(s) that dictate the balance between OC preservation and utilization by microorganisms. Sediment cores from the North Atlantic gyre (KN223), South Pacific Gyre (Knox02-RR), and Peru Basin (IODP site 1231) allowed for a global comparison and a test of how sediment lithology and redox state affect OC preservation. OC was present in low concentrations in all samples (0.01—0.61%), at depths up to 112 meters below seafloor and estimated sediment ages of up to 50 million years. Synchrotron-based near edge X-ray absorption fine structure (NEXAFS) spectroscopy was conducted on over 100 samples, one of the first applications of NEXAFS to sedimentary environments. NEXAFS revealed an OC reservoir dominated by amide and carboxylic functionalities in a scaffolding of O-alkyl and aliphatic carbons. Detection of extractable, extracellular proteins supports this composition and suggests that sedimentary OC is protein-derived. This composition was common across all sites and depths, implicating physical rather than chemical mechanisms in OC preservation on long timescales. This study thereby points to physical access rather than energy or metabolic potential as a key constraint on subsurface heterotrophic life.

Project Maintainers
NameAffiliationRoleContact
Emily R. EstesWoods Hole Oceanographic Institution (WHOI)Principal Investigator
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