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| Format: | Dataset Open Access |
| Language: | en |
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PANGAEA
2015
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| Online Access: | https://doi.org/10.1594/PANGAEA.841812 |
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| _version_ | 1867172331834572800 |
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| author | Kao, Shuh-Ji Zheng, Li-Wei Hsiao, Silver Sung-Yun |
| author_facet | Kao, Shuh-Ji Zheng, Li-Wei Hsiao, Silver Sung-Yun |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | Total organic carbon to total nitrogen ratio (C/N) and their isotopic composition (d13CTOC vs. d15NTN) are oft-applied proxies to discern terrigenous from marine sourced organics and to unravel the ancient environmental information. In high depositional Asian marginal seas, matrixes, including N-bearing minerals, dilution leads to illusive and even contradictive interpretations. We use KOH-KOBr to separate operationally defined total organic matter into oxidizable (labile) and residual fractions for content and isotope measurements. In a sediment core in the Okinawa Trough, significant amounts of carbon and nitrogen existed in the residual phase, in which the C/N ratio was ~9 resembling most documented sedimentary bulk C/N ratios in the China marginal seas. Such similarity creates a pseudo-C/N interrupting the application of bulk C/N. The residual carbon, though composition unknown, it displayed a d13C range (-22.7 to -18.9 per mil, mean -20.7 per mil) similar to black carbon (-24.0 to -22.8 per mil) in East China Sea surface sediments. After removing residual fraction, we found the temporal pattern of d13CLOC in labile fraction (LOC) was more variable but broadly agreed with the atmospheric pCO2-induced changes in marine endmember d13C. Thus, we suggested adding pCO2-induced endmember modulation into two-endmember mixing model for paleo-environment reconstruction. Meanwhile, the residual nitrogen revealed an intimate association with illite content suggesting its terrestrial origin. Additionally, d15N in residual fraction likely carried the climate imprint from land. Further studies are required to explore the controlling factors for carbon and nitrogen isotopic speciation and to retrieve the information locked in the residual fraction. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_841812 |
| institution | PANGAEA |
| language | en |
| publishDate | 2015 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Contents and isotopic speciation of sedimentary carbon and nitrogen in sediment core MD01-2404, the Okinawa Trough Kao, Shuh-Ji Zheng, Li-Wei Hsiao, Silver Sung-Yun AGE; Carbon, organic, residual; Carbon, organic, total; DEPTH, sediment/rock; East China Sea, Pacific Ocean; Giant piston corer; GPC; IMAGES; IMAGES VII - WEPAMA; International Marine Global Change Study; Marion Dufresne (1995); MD012404; MD01-2404; MD122; Nitrogen, carbonate free fraction; Nitrogen, inorganic; δ13C, organic carbon; δ13C, residual organic carbon; δ15N, carbonate free fraction; δ15N, inorganic Total organic carbon to total nitrogen ratio (C/N) and their isotopic composition (d13CTOC vs. d15NTN) are oft-applied proxies to discern terrigenous from marine sourced organics and to unravel the ancient environmental information. In high depositional Asian marginal seas, matrixes, including N-bearing minerals, dilution leads to illusive and even contradictive interpretations. We use KOH-KOBr to separate operationally defined total organic matter into oxidizable (labile) and residual fractions for content and isotope measurements. In a sediment core in the Okinawa Trough, significant amounts of carbon and nitrogen existed in the residual phase, in which the C/N ratio was ~9 resembling most documented sedimentary bulk C/N ratios in the China marginal seas. Such similarity creates a pseudo-C/N interrupting the application of bulk C/N. The residual carbon, though composition unknown, it displayed a d13C range (-22.7 to -18.9 per mil, mean -20.7 per mil) similar to black carbon (-24.0 to -22.8 per mil) in East China Sea surface sediments. After removing residual fraction, we found the temporal pattern of d13CLOC in labile fraction (LOC) was more variable but broadly agreed with the atmospheric pCO2-induced changes in marine endmember d13C. Thus, we suggested adding pCO2-induced endmember modulation into two-endmember mixing model for paleo-environment reconstruction. Meanwhile, the residual nitrogen revealed an intimate association with illite content suggesting its terrestrial origin. Additionally, d15N in residual fraction likely carried the climate imprint from land. Further studies are required to explore the controlling factors for carbon and nitrogen isotopic speciation and to retrieve the information locked in the residual fraction. |
| title | Contents and isotopic speciation of sedimentary carbon and nitrogen in sediment core MD01-2404, the Okinawa Trough |
| topic | AGE; Carbon, organic, residual; Carbon, organic, total; DEPTH, sediment/rock; East China Sea, Pacific Ocean; Giant piston corer; GPC; IMAGES; IMAGES VII - WEPAMA; International Marine Global Change Study; Marion Dufresne (1995); MD012404; MD01-2404; MD122; Nitrogen, carbonate free fraction; Nitrogen, inorganic; δ13C, organic carbon; δ13C, residual organic carbon; δ15N, carbonate free fraction; δ15N, inorganic |
| url | https://doi.org/10.1594/PANGAEA.841812 |