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Development of a modified SEDEX phosphorus speciation method for ancient rocks and modern iron-rich sediments

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Development of a modified SEDEX phosphorus speciation method for ancient rocks and modern iron-rich sediments. / Thompson, J.; Poulton, S.W.; Guilbaud, R. et al.
In: Chemical Geology, Vol. 524, 05.10.2019, p. 383-393.

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Thompson J, Poulton SW, Guilbaud R, Doyle KA, Reid S, Krom MD. Development of a modified SEDEX phosphorus speciation method for ancient rocks and modern iron-rich sediments. Chemical Geology. 2019 Oct 5;524:383-393. Epub 2019 Jul 2. doi: 10.1016/j.chemgeo.2019.07.003

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Thompson, J. ; Poulton, S.W. ; Guilbaud, R. et al. / Development of a modified SEDEX phosphorus speciation method for ancient rocks and modern iron-rich sediments. In: Chemical Geology. 2019 ; Vol. 524. pp. 383-393.

Bibtex

@article{812900484ffa4bc0ab574e18453c594c,
title = "Development of a modified SEDEX phosphorus speciation method for ancient rocks and modern iron-rich sediments",
abstract = "We report the development of a modified method for evaluating different reservoirs of sedimentary phosphorus (P) in ancient marine sedimentary rocks and in modern Fe-rich sediments. Utilising the existing SEDEX scheme for P partitioning in modern sediments, we initially demonstrate limitations in the application of the original scheme to sediments and rocks containing crystalline hematite and magnetite. We tested additional extractions for these crystalline Fe phases, using both synthetic minerals, and modern and ancient sediments. The addition of 6 h oxalate and 6 h citrate-dithionate-acetate extractions considerably enhanced the total recovery of synthetic magnetite and hematite to 88.7 ± 1.1% and 76.9 ± 3.8%, respectively. In addition, application of the 6 h oxalate extraction to synthetic P-containing magnetite recovered 93.9 ± 1.7% of the Fe present and 88.2 ± 12.8% of the co-precipitated P. Based upon these results we developed a modified SEDEX extraction scheme. The modified scheme was applied to modern Fe-rich sediments from Golfo Dulce, Costa Rica, which resulted in 16% higher Fe-bound P recovery. Application of the scheme to a variety of ancient marine rocks increased the recovery of Fe-bound P by up to 22%. We also highlight the potential for authigenic carbonate fluorapatite to convert to more crystalline apatite in ancient rocks during deep burial and metamorphism. We suggest that in such systems minimum and maximum estimates of the total reactive P pool may be calculated with and without the inclusion of crystalline P. It is noted that the application of the revised method may have important implications for understanding the cycling of P in ancient marine environments.",
keywords = "Hematite, Magnetite, Phosphorus, SEDEX, Sequential extractions, Crystalline rocks, Extraction, Iron, Oxalic acid, Phosphate minerals, Recovery, Sedimentology, Sediments, Authigenic carbonates, Co-precipitated, Marine environment, Modified scheme, Oxalate extraction, Phosphorus speciation, Sequential extraction, Sedimentary rocks",
author = "J. Thompson and S.W. Poulton and R. Guilbaud and K.A. Doyle and S. Reid and M.D. Krom",
year = "2019",
month = oct,
day = "5",
doi = "10.1016/j.chemgeo.2019.07.003",
language = "English",
volume = "524",
pages = "383--393",
journal = "Chemical Geology",
issn = "0009-2541",
publisher = "Elsevier",

}

RIS

TY - JOUR

T1 - Development of a modified SEDEX phosphorus speciation method for ancient rocks and modern iron-rich sediments

AU - Thompson, J.

AU - Poulton, S.W.

AU - Guilbaud, R.

AU - Doyle, K.A.

AU - Reid, S.

AU - Krom, M.D.

PY - 2019/10/5

Y1 - 2019/10/5

N2 - We report the development of a modified method for evaluating different reservoirs of sedimentary phosphorus (P) in ancient marine sedimentary rocks and in modern Fe-rich sediments. Utilising the existing SEDEX scheme for P partitioning in modern sediments, we initially demonstrate limitations in the application of the original scheme to sediments and rocks containing crystalline hematite and magnetite. We tested additional extractions for these crystalline Fe phases, using both synthetic minerals, and modern and ancient sediments. The addition of 6 h oxalate and 6 h citrate-dithionate-acetate extractions considerably enhanced the total recovery of synthetic magnetite and hematite to 88.7 ± 1.1% and 76.9 ± 3.8%, respectively. In addition, application of the 6 h oxalate extraction to synthetic P-containing magnetite recovered 93.9 ± 1.7% of the Fe present and 88.2 ± 12.8% of the co-precipitated P. Based upon these results we developed a modified SEDEX extraction scheme. The modified scheme was applied to modern Fe-rich sediments from Golfo Dulce, Costa Rica, which resulted in 16% higher Fe-bound P recovery. Application of the scheme to a variety of ancient marine rocks increased the recovery of Fe-bound P by up to 22%. We also highlight the potential for authigenic carbonate fluorapatite to convert to more crystalline apatite in ancient rocks during deep burial and metamorphism. We suggest that in such systems minimum and maximum estimates of the total reactive P pool may be calculated with and without the inclusion of crystalline P. It is noted that the application of the revised method may have important implications for understanding the cycling of P in ancient marine environments.

AB - We report the development of a modified method for evaluating different reservoirs of sedimentary phosphorus (P) in ancient marine sedimentary rocks and in modern Fe-rich sediments. Utilising the existing SEDEX scheme for P partitioning in modern sediments, we initially demonstrate limitations in the application of the original scheme to sediments and rocks containing crystalline hematite and magnetite. We tested additional extractions for these crystalline Fe phases, using both synthetic minerals, and modern and ancient sediments. The addition of 6 h oxalate and 6 h citrate-dithionate-acetate extractions considerably enhanced the total recovery of synthetic magnetite and hematite to 88.7 ± 1.1% and 76.9 ± 3.8%, respectively. In addition, application of the 6 h oxalate extraction to synthetic P-containing magnetite recovered 93.9 ± 1.7% of the Fe present and 88.2 ± 12.8% of the co-precipitated P. Based upon these results we developed a modified SEDEX extraction scheme. The modified scheme was applied to modern Fe-rich sediments from Golfo Dulce, Costa Rica, which resulted in 16% higher Fe-bound P recovery. Application of the scheme to a variety of ancient marine rocks increased the recovery of Fe-bound P by up to 22%. We also highlight the potential for authigenic carbonate fluorapatite to convert to more crystalline apatite in ancient rocks during deep burial and metamorphism. We suggest that in such systems minimum and maximum estimates of the total reactive P pool may be calculated with and without the inclusion of crystalline P. It is noted that the application of the revised method may have important implications for understanding the cycling of P in ancient marine environments.

KW - Hematite

KW - Magnetite

KW - Phosphorus

KW - SEDEX

KW - Sequential extractions

KW - Crystalline rocks

KW - Extraction

KW - Iron

KW - Oxalic acid

KW - Phosphate minerals

KW - Recovery

KW - Sedimentology

KW - Sediments

KW - Authigenic carbonates

KW - Co-precipitated

KW - Marine environment

KW - Modified scheme

KW - Oxalate extraction

KW - Phosphorus speciation

KW - Sequential extraction

KW - Sedimentary rocks

U2 - 10.1016/j.chemgeo.2019.07.003

DO - 10.1016/j.chemgeo.2019.07.003

M3 - Journal article

VL - 524

SP - 383

EP - 393

JO - Chemical Geology

JF - Chemical Geology

SN - 0009-2541

ER -