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Title: Characterization of natural organic matter in low-carbon sediments: Extraction and analytical approaches

Abstract

Sediment-associated natural organic matter (NOM) is a complex assemblage of organic molecules with a wide range of sizes, functional groups, and structures, which is intricately associated with mineral particles. Organic carbon (OC) concentrations in subsurface sediments are typically 10 to 200 times lower than in surface soils, posing a distinct challenge for characterization. A range of chemical extractions were evaluated for extraction of NOM, and a NOM extraction scheme was developed using a combination of sequential extraction with water (MQ) and sodium pyrophosphate at pH 10 (PP), and purification by dialysis and solid phase extraction in order to isolate different fractions of sediment-associated NOM. Analysis of these different NOM fractions was then carried out by Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) spectroscopy, and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). The OC extraction efficiency of the tested extractions followed the order PP>NaOH>HCl=hydroxylamine hydrochloride>dithionite. Greater concentrations of OC in PP vs NaOH extracts suggest that metal complexation and/or ligand exchange plays an important role in OC stabilization. Characterization of different pools of extraction NOM by FITR shows that the water soluble fraction has a higher fraction of aliphatic and carboxylic groups, while the PP fractions have highermore » C=C groups. This trend from aliphatic to more aromatic is also supported by the UV-Vis and ESI-FTICR-MS data.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1439700
Report Number(s):
PNNL-SA-123194
Journal ID: ISSN 0146-6380; 48252; 48046; KP1704020
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Organic Geochemistry
Additional Journal Information:
Journal Volume: 114; Journal Issue: C; Journal ID: ISSN 0146-6380
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
Environmental Molecular Sciences Laboratory

Citation Formats

Fox, Patricia M., Nico, Peter S., Tfaily, Malak M., Heckman, Katherine, and Davis, James A. Characterization of natural organic matter in low-carbon sediments: Extraction and analytical approaches. United States: N. p., 2017. Web. doi:10.1016/j.orggeochem.2017.08.009.
Fox, Patricia M., Nico, Peter S., Tfaily, Malak M., Heckman, Katherine, & Davis, James A. Characterization of natural organic matter in low-carbon sediments: Extraction and analytical approaches. United States. doi:10.1016/j.orggeochem.2017.08.009.
Fox, Patricia M., Nico, Peter S., Tfaily, Malak M., Heckman, Katherine, and Davis, James A. Fri . "Characterization of natural organic matter in low-carbon sediments: Extraction and analytical approaches". United States. doi:10.1016/j.orggeochem.2017.08.009.
@article{osti_1439700,
title = {Characterization of natural organic matter in low-carbon sediments: Extraction and analytical approaches},
author = {Fox, Patricia M. and Nico, Peter S. and Tfaily, Malak M. and Heckman, Katherine and Davis, James A.},
abstractNote = {Sediment-associated natural organic matter (NOM) is a complex assemblage of organic molecules with a wide range of sizes, functional groups, and structures, which is intricately associated with mineral particles. Organic carbon (OC) concentrations in subsurface sediments are typically 10 to 200 times lower than in surface soils, posing a distinct challenge for characterization. A range of chemical extractions were evaluated for extraction of NOM, and a NOM extraction scheme was developed using a combination of sequential extraction with water (MQ) and sodium pyrophosphate at pH 10 (PP), and purification by dialysis and solid phase extraction in order to isolate different fractions of sediment-associated NOM. Analysis of these different NOM fractions was then carried out by Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) spectroscopy, and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). The OC extraction efficiency of the tested extractions followed the order PP>NaOH>HCl=hydroxylamine hydrochloride>dithionite. Greater concentrations of OC in PP vs NaOH extracts suggest that metal complexation and/or ligand exchange plays an important role in OC stabilization. Characterization of different pools of extraction NOM by FITR shows that the water soluble fraction has a higher fraction of aliphatic and carboxylic groups, while the PP fractions have higher C=C groups. This trend from aliphatic to more aromatic is also supported by the UV-Vis and ESI-FTICR-MS data.},
doi = {10.1016/j.orggeochem.2017.08.009},
journal = {Organic Geochemistry},
issn = {0146-6380},
number = C,
volume = 114,
place = {United States},
year = {2017},
month = {12}
}