| Registro completo |
| Provedor de dados: |
ArchiMer
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| País: |
France
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| Título: |
Acid digestion on river influenced shelf sediment organic matter: Carbon and Nitrogen contents and isotopic ratios
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| Autores: |
Pasquier, Virgil
Sansjofre, Pierre
Lebeau, Oanez
Liorzou, Celine
Rabineau, Marina
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| Data: |
2018-01
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| Ano: |
2018
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| Resumo: |
Rationale Natural stable isotopes ratios (d13Corg and 15N vales) and associated elemental concentrations (i.e. total organic carbon and total nitrogen contents) preserved in marine sediments are frequently used for the determination of paleoenvironmental processes such as the origin of organic matter. Previous studies highlighted biases in the determination of such geochemical proxies due to pre-analysis acid treatment methods. This study is the first systematic comparison of the effect of acid treatment methods on bulk organic matter using a unique sedimentary system, under two contrasting climatic contexts (i.e. glacial vs interglacial). Methods We used the most common method for pre-treatment analysis, which consists of the acidification of bulk sediments followed by several de-ionised water rinses. We investigated the effect of acid type (hydrochloric acid and acetic acid), and also acid strength (from 0.2 to 10 mol L-1) on the δ13Corg, δ15N, TOC, TN and C/N values of three samples from the Gulf of Lion. Two of them (S302 and S102) were deposited during glacial maxima (i.e. high sedimentation rate, low porosity and high terrestrial inputs) whereas S157 characterizes interglacial conditions (high porosity, high foraminifera content, low sedimentation rates and low terrestrial inputs). Results For all three samples the δ13Corg values are between -21.7 and -24.4‰ with the TOC varying from 0.56 and 0.84 %wt/wt. The δ15N values are more stable with an average value of 3.0 ± 0.1‰ with a TN average of 0.08 ± 0.002 %wt/wt. Conclusions We show that acid type did not significantly affect results. We also find that (i) glacial and interglacial samples do not react similarly to acid pre-treatment, (ii) high acid strength (>1.5 mol L-1) induces significant bias on δ13Corg and TOC values, and therefore on C/N ratios; (iii) 25% of an isotopically distinct pool of organic carbon was lost when using acid concentrations of 0.2-1.5 mol L-1, affecting δ13Corg values by more than 1.5‰; and (iv) geochemical evidence indicates that the leachable organic carbon pool is preferentially composed of terrestrial organic matter. These findings call for precautions when using C/N ratios and associated δ13Corg values for paleoenvironmental and climate reconstructions.
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| Tipo: |
Text
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| Idioma: |
Inglês
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| Identificador: |
https://archimer.ifremer.fr/doc/00407/51830/52429.pdf
DOI:10.1002/rcm.8014
https://archimer.ifremer.fr/doc/00407/51830/
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| Editor: |
Wiley
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| Formato: |
application/pdf
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| Fonte: |
Rapid Communications In Mass Spectrometry (0951-4198) (Wiley), 2018-01 , Vol. 32 , N. 2 , P. 86-92
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| Direitos: |
2017 John Wiley & Sons, Ltd.
info:eu-repo/semantics/openAccess
restricted use
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