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Title: Characterization of minerals and organic phosphorus species in marine sediments using soft X-ray fluorescence spectromicroscopy.

Abstract

Phosphorus Near Edge X-ray Fluorescence Spectroscopy (P-NEXFS) data were collected on phosphorus containing phases including organic and inorganic compounds and minerals. Although phases containing P in the plus five oxidation state P(V) in a tetrahedral PO{sub 4} structure have similar primary fluorescence peak positions, the size, shape, and positions of secondary spectral features are diagnostic for different compounds and minerals. In particular, calcium phosphates exhibited a notable post-peak shoulder at 2154.5 eV, while oxidized iron phosphates had a distinctive pre-peak feature at 2148 eV. Polyphosphates have a broad secondary peak located approximately 2 eV higher in energy than a similar feature in phosphate esters and diesters. Compounds containing P(V) in structures other than PO{sub 4} tetrahedra such as phosphonates have a primary peak shifted about 1 eV lower than corresponding organo-phosphates. Organo-phosphates with P in the plus three oxidation state P(III) such as phosphines had primary fluorescence peaks shifted still further down in energy (2-3 eV). The substitution of aromatic carbon groups in close proximity to P structures in organic compounds generated both pre- and post-peak features as well as a number of secondary peaks. In addition, X-ray fluorescence mapping of P, Si, Al, Mg, and Na was conducted onmore » a marine sediment sample with sub-micron spatial resolution. Phosphorus was heterogeneously distributed in the sample and not correlated on a broad scale with any other element examined. Much of the P present in the sample was located in small, 0.6-8 {micro}m size, P-rich domains. Several P-rich regions were examined with P-NEXFS using a focused beam with 60 nm resolution and were found to consist of either calcium phosphate or polyphosphate phases. The presence of significant polyphosphate-dominated regions in a marine sediment sample supports the recent observations that such phases can play an important role in marine P cycling. The combination of fluorescence mapping and P-NEXFS data collection on fine particles provides a powerful new tool for environmental phosphorus studies.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
National Science Foundation (NSF); USDOE Office of Science (SC)
OSTI Identifier:
947545
Report Number(s):
ANL/XSD/JA-63463
Journal ID: ISSN 0304-4203; MRCHBD; TRN: US200905%%12
DOE Contract Number:  
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Mar. Chem.; Journal Volume: 103; Journal Issue: 2007
Country of Publication:
United States
Language:
ENGLISH
Subject:
54 ENVIRONMENTAL SCIENCES; X-RAY FLUORESCENCE ANALYSIS; MINERALS; ORGANIC PHOSPHORUS COMPOUNDS; PHOSPHATES; PHOSPHONATES; SEDIMENTS; VALENCE

Citation Formats

Brandes, J. A., Ingall, E., Paterson, D., X-Ray Science Division, Skidaway Inst. of Oceanography, and Georgia Inst. of Tech. Characterization of minerals and organic phosphorus species in marine sediments using soft X-ray fluorescence spectromicroscopy.. United States: N. p., 2007. Web. doi:10.1016/j.marchem.2006.09.004.
Brandes, J. A., Ingall, E., Paterson, D., X-Ray Science Division, Skidaway Inst. of Oceanography, & Georgia Inst. of Tech. Characterization of minerals and organic phosphorus species in marine sediments using soft X-ray fluorescence spectromicroscopy.. United States. doi:10.1016/j.marchem.2006.09.004.
Brandes, J. A., Ingall, E., Paterson, D., X-Ray Science Division, Skidaway Inst. of Oceanography, and Georgia Inst. of Tech. Mon . "Characterization of minerals and organic phosphorus species in marine sediments using soft X-ray fluorescence spectromicroscopy.". United States. doi:10.1016/j.marchem.2006.09.004.
@article{osti_947545,
title = {Characterization of minerals and organic phosphorus species in marine sediments using soft X-ray fluorescence spectromicroscopy.},
author = {Brandes, J. A. and Ingall, E. and Paterson, D. and X-Ray Science Division and Skidaway Inst. of Oceanography and Georgia Inst. of Tech.},
abstractNote = {Phosphorus Near Edge X-ray Fluorescence Spectroscopy (P-NEXFS) data were collected on phosphorus containing phases including organic and inorganic compounds and minerals. Although phases containing P in the plus five oxidation state P(V) in a tetrahedral PO{sub 4} structure have similar primary fluorescence peak positions, the size, shape, and positions of secondary spectral features are diagnostic for different compounds and minerals. In particular, calcium phosphates exhibited a notable post-peak shoulder at 2154.5 eV, while oxidized iron phosphates had a distinctive pre-peak feature at 2148 eV. Polyphosphates have a broad secondary peak located approximately 2 eV higher in energy than a similar feature in phosphate esters and diesters. Compounds containing P(V) in structures other than PO{sub 4} tetrahedra such as phosphonates have a primary peak shifted about 1 eV lower than corresponding organo-phosphates. Organo-phosphates with P in the plus three oxidation state P(III) such as phosphines had primary fluorescence peaks shifted still further down in energy (2-3 eV). The substitution of aromatic carbon groups in close proximity to P structures in organic compounds generated both pre- and post-peak features as well as a number of secondary peaks. In addition, X-ray fluorescence mapping of P, Si, Al, Mg, and Na was conducted on a marine sediment sample with sub-micron spatial resolution. Phosphorus was heterogeneously distributed in the sample and not correlated on a broad scale with any other element examined. Much of the P present in the sample was located in small, 0.6-8 {micro}m size, P-rich domains. Several P-rich regions were examined with P-NEXFS using a focused beam with 60 nm resolution and were found to consist of either calcium phosphate or polyphosphate phases. The presence of significant polyphosphate-dominated regions in a marine sediment sample supports the recent observations that such phases can play an important role in marine P cycling. The combination of fluorescence mapping and P-NEXFS data collection on fine particles provides a powerful new tool for environmental phosphorus studies.},
doi = {10.1016/j.marchem.2006.09.004},
journal = {Mar. Chem.},
number = 2007,
volume = 103,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}