• Economic and Environmental Geology
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• v.43 no.1
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• pp.1-12
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• 2010

Geochemical approaches on the two recovered piston cores were performed to understand the characteristics of organic matters and the influence of the sea level variation of the East Sea in the Hupo Basin since the Holocene. The analyzing results on organic components (TOC and TN), and isotopic compositions of organic matters showed the variation to core locations and sampling depths. In core 08HZP-01, their values were gradually changed with depth from 4 mbsf to seafloor. However, rapid variation was observed at the boundary of 4.71 mbsf (meter below seafloor) in core 08HZP-03. Based on TOC/TN, $\delta^{13}C_{org}$ and $\delta^{15}N_{org}$, the origin of organic matters in the Hupo Basin can be divided into three groups; 1) predominant marine algae, 2) $C_3$ land plant, and 3) mixture of $C_3$ land plant and marine/freshwater algae. It is likely that the vertical and spatial variations of organic and isotopic compositions reflect the shifts in sedimentary environment (including sediment transportation) by ocean currents and sea-level changes and others during the Holocene period.

• Economic and Environmental Geology
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• v.40 no.5
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• pp.605-622
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• 2007

Elemental, Rock-Eval pyrolysis and isotopic analysis of the core sediments from the northwestern and eastern Ulleung Basin of the East were carried out to identify their geochemical characteristics, spatial and vertical variation and origin of organic matter in Upper Quaternary sediments from the northwestern and eastern Ulleung Basin of the East Sea. TOC, m and TS did not show spatial variation between the sampling locations whereas they showed systematic vertical variation associated with MIS stages related to the sea-level change of the East Sea. It is suggested that these past changes of sea-level influenced the sedimentary depositional environments and/or diagenesis which resulted the patterns observed in this study. Based on the results of TOC/N, TS/TOC, ${\delta}^{13}C_{org}\;and\;{\delta}^{15}N_{org}$ analysis, organic matters in the study area appears to be predominantly originated from the marine algae rather than land plant and deposited under normal marine oxic condition during MIS I and MIS III period, and under euxinic/anoxic condition during MIS II period. TOC/N, ${\delta}^{13}C_{org}\;and\;{\delta}^{15}N_{org}$ have a relatively constant value irrespective of MIS stages, implying that the organic matter source does not change by the sea-level fluctuations. However, the results of Rock-Eval pyrolysis indicates that the organic matter is in immature stage and originated from land-plant (Type III), locating in the immature stage land plant (Type III). Similar differences were reported from other areas such as the Atlantic Ocean, Iberia Abyssal Plain, Mediterranean Sea, suggesting that Rock-Eval method does not exactly reflect the characteristic of immature organic matters. Accordingly, the application of Rock-Eval pyrolysis for delineating the source of immature organic matters should be approached with caution and all other geochemical proxies should be considered altogether at the same time.

• Economic and Environmental Geology
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• v.40 no.5
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• pp.623-633
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• 2007

Stable isotope and biomarker analyses were carried out for the organic sediments from the exploratory wells in the Jeju Basin in order to understand the characteristics of organic matter. Organic matter in Geobuk-1, Okdom-1, JDZ VII-1 and VII-2 well is predominantly originated from land plants rather than marine algae according to carbon $({\delta}^{13}C_{org})$ and nitrogen $({\delta}^{15}N_{org})$ isotopic compositions. In the Geobuk-1, geochemical characteristics such as carbon $({\delta}^{13}C_{org})$, nitrogen ($({\delta}^{15}N_{org})$ and TOC contents are obviously changed by the depth 2,400 m, which is likely due to the change of origin of organic matter, sedimentary process or sedimentary environments. Analysis of the saturated fraction of the bitumen suggests the contribution of migrated oil to the indigenous bitumen from the samples 2,509, 2,833 and 3,163 m of the JDZ YII-1 and 3,253 m of the Geobuk-1 well. However, this characteristics can be derived from the contribution of the original organic matter. Based on the biomarker analysis, the samples from the Okdom-1 and Geobuk-1 appear to represent sedimentary organic matter of similar composition, that is rotatively immature, and which was probably deposited in the fluvio-deltaic setting with minor offshore marine influence. The samples from JDZ VII-1 appear to have been deposited in a more terrestrially dominated setting.

• Journal of the korean society of oceanography
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• v.31 no.3
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• pp.134-143
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• 1996

Sediment cores were collected from one site each in Amursky and Ussuriysky Bays in the Peter the great Bay for $^{210}Pb$, org C, N, biogenic Si, ${\delta}^{13}$C and ${\delta}^{15}$N analysis to elucidate the processes of biogenic particulate matter accumulation and early diagenetic change in the upper sediment column. Biogeochemistry at the core sites of both bays shows differences in sedimentation rate, sediment mixing, and diagenetic processes of particulate biogenic matter. Sedimentary organic matter at the core sites in both bays appeared to be largely derived from marine origin. Sedimentation rates are 173 and 118 mg $cm^{-2}$ $yr^{-1}$(0.13 and 0.11 cm $yr^{-1}$) in Amursky and Ussuriysky Bays, respectively. The surface mixed layer in the core top was present in Amursky Bay but not in Ussuriysky Bay. At the core site in Amursky Bay, incorporation of biogenic particulate matter into the sediment from the overlying waters is 236, 19, 142 mmol $cm^{-2}$ $yr^{-1}$ for organic C, N, and biogenic Si, respectively. Of which about 70${\%}$ of organic C and biogenic Si are degraded within the upper 25 cm sediment and the rest are buried at 25 cm sediment horizon. At the core site in Ussuriysky Bay, incorporation of biogenic particulate matter into the sediment from overlying waters is 164, 18, 76 mmol $cm^{-2}$ $yr^{-1}$ for organic C, N, and biogenic Si, respectively. Of which less than 50${\%}$ of organic C and biogenic Si are degraded within the upper 25 cm sediment and the remainder are buried at 25 cm sediment horizon. This large difference of degradation of biogenic matter in the upper 25 cm sediment column appears to be resulted from the difference in sediment mixing rates between the two cores.

• Ocean and Polar Research
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• v.36 no.1
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• pp.25-37
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• 2014

To understand the degradation processes of organic matter related to sulfate reduction by Sulfate Reduction Bacteria (SRB) in the tidal flat sediments of Hwang-do and Sogeun-ri, Tae-an Peninsula in Chungnam-do, biogeochemical characteristics were analyzed and highlighted using specific microbial biomarkers. The organic geochemical parameters (TOC, ${\delta}^{13}C_{org}$, C/N ratio, long-chain-n-alkane) indicate that most of the organic matter has been derived from marine phytoplankton and bacteria in the fine-grained sediment of Sogeun-ri, although terrestrial plant components have occasionally been incorporated to a significant degree in the coarse-grained sediment of Hwang-do. The concentration of sulfate in pore water is a constant tendency with regard to depth profile, while methane concentration appears to be slightly different with regard to depth profile at the two sites. Especially, the sum of bacteria fatty acid (a-C15:0 + i-C15:0 + C16:1w5) confirms that the these concentrations in Sogeun-ri are related to the degradation of Benzene, Toluene, Ethylbenzene and Xylene (BTEX) compounds from the crude oil retained in the sediments as a result of the Hebei Spirit oil-spill accident in 2007. The methane-related microbial communities as shown by lipid biomarkers (crocetane, PMI) are larger in some sedimentary sections of Hwang-do than in the Sogeunri tidal flat. These findings suggest that methane production by microbiological processes is clearly governed by SRB activity along the vertical succession in organic-enriched tidal flats.