Stable carbon and nitrogen isotopic composition of gas hydrate-bearing sediment from Hydrate Ridge,Cascadia Margin  

作　　者：Young-Joo Lee 

机构地区：[1]Petroleum and Marine Resources Research Division, Korea Institute of Geoscience and Mineral Resources, Daejon 305-350,South Korea

出　　处：《Science China Earth Sciences》2006年第8期872-880,共9页中国科学（地球科学英文版）

基　　金：This work was supported by the National Major Fundamental Research and Development Project of China(Grant No.G2000046704);the National Natural Science Foundation of China(Grant No.40576059).

摘　　要：54 sediments were sampled at 5 sites, 1244, 1245, 1246,1250 and 1251 from ODPLeg 204, Hydrate Ridge, Cascadia Margin. The stable carbon and nitrogen isotopic composition,δ^(13)C of organic matter and δ^(15)N, have been used to characterize the depositional variationof sediments with gas hydrate bearing. Values of δ^(13)C of bulk organic matter range between-22.37 per thousand and -24.72 per thousand PDB, with a mean value of -23.54 ± 1.17 per thousandPDB; δ^(15)N of the same sedimentary samples range from 3.30 per thousand to 5.68 per thousand,with a mean value of 4.49 ± 1.19 per thousand; Values of C/N ratio range from 4.53 to 9.26, with amean value of 6.90 ± 2.37. The occurrence of gas hydrate changed the diagenetic evolution trend ofthe carbon and nitrogen in organic matter. The δ^(15)N and C/N ratio depletion suggest that thenitrogen fixation related with the bacteria/archaea maybe occurred in the sediments near thehydrate. The stable carbon and nitrogen isotopic composition could be used to evaluate thedepositional environment in the study area.54 sediments were sampled at 5 sites, 1244, 1245, 1246, 1250 and 1251 from ODP Leg 204, Hydrate Ridge, Cascadia Margin. The stable carbon and nitrogen isotopic composition, δ C of 13 organic matter and δ N, have been used to characterize the depositional variation of sediments with 15 gas hydrate bearing. Values of δ C of bulk organic matter range between ?22.37‰ and ?24.72‰ 13 PDB, with a mean value of ?23.54±1.17‰ PDB; δ N of the same sedimentary samples range from 15 3.30‰ to 5.68‰, with a mean value of 4.49±1.19‰; Values of C/N ratio range from 4.53 to 9.26, with a mean value of 6.90±2.37. The occurrence of gas hydrate changed the diagenetic evolution trend of the carbon and nitrogen in organic matter. The δ N and C/N ratio depletion suggest that the nitrogen 15 fixation related with the bacteria/archaea maybe occurred in the sediments near the hydrate. The stable carbon and nitrogen isotopic composition could be used to evaluate the depositional environ- ment in the study area.

关 键 词：gas hydrate  carbon isotopes  NITROGEN isotopes  C/N ratio  NITROGEN fixation. 

分 类 号：P597[天文地球—地球化学]