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Study on transport of terrestrial organic matter into marginal sea inferred from biomarker and stable isotope analysis of sedimentary organic matter.

根据沉积有机质的生物标志物和稳定同位素分析推断陆地有机质向边缘海的迁移研究。

基本信息

批准号：
11440164
负责人：
MINAGAWA Masao
金额：
$ 9.79万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

The purpose of this project is to reveal historical changes of an interrelation between marine biological production and terrestrial organic matter flux in the North Pacific ocean and its adjacent seas.Sediment core samples were collected from various basins such as Shatsky rise in the North Pacific, Lake Abashiri, and the estuary of Changjiang river etc. Geochemical proxies in sedimentary organic matter, such as carbon and nitrogen stable isotopes, n-alkane, alkenone and sterol were analyzed to reconstruct the temporal change of marine biological productivity and atmospheric precipitation of terrestrial biomarkers. We estimated the historical variation of sedimentary flux of marine planktonic components using alkenone as a planktonic molecular markers. The result showed ten times greater accumulation rate of terrestrial organic matter in the last glacial period, suggesting that aeolian dust flux might be increased in the ice age. We studied also a boring core sample from Lake Abashiri that located in east Hokkaido, and found temporal change of sedimentary organic matter in the last 10 k years, indicating that a unique excursion of nitrogen isotope ratio in sedimentary organic matter. The result indicates that δ^<15>N may be useful tool to figure out the climatic change of coastal environment in last 20 k years. The isotopic results of sediment samples from the sourth of Thailand coast indicated that organic carbon and nitrogen isotopic composition have already recorded evidence of recent anthropological activities, urbanization and eutrophication in watershed. A boring core from Changjian river mouth represented that ^<15>N might be enriched in recent soil perhaps due to nitrogen accumulation in the growth of human population. This work successfully indicated that sedimentary organic matters are useful to study temporal change of marine and lacustrine environment since the last glacial period.

该项目的目的是揭示北太平洋及其邻近海域海洋生物生产与陆地有机质通量之间相互关系的历史变化。在北太平洋沙斯基隆起、阿巴什里湖、长江口等不同盆地采集了沉积物岩心样品。通过分析沉积有机质中碳、氮稳定同位素、正构烷烃、烯酮和甾醇等地球化学指标，重建海洋生物生产力和陆相生物标志物大气降水的时间变化。以烯烃酮为浮游生物分子标志物，估算了海洋浮游生物组分沉积通量的历史变化。结果表明，末次冰期陆相有机质积累速率提高了10倍，表明冰期风沙通量可能增加。研究了北海道东部Abashiri湖钻孔岩心样品，发现了近10 k来沉积有机质的时间变化，表明沉积有机质中氮同位素比值发生了独特的偏移。结果表明，δ^<15>N可能是计算近20 k来沿海环境气候变化的有用工具。泰国南部海岸沉积物样品的同位素结果表明，有机碳和氮同位素组成已经记录了流域近期人类活动、城市化和富营养化的证据。长剑河口钻孔岩心表明，近代土壤中N <15>的富集可能是由于人口增长过程中氮的积累所致。这项工作成功地表明，沉积有机质对研究末次冰期以来海洋和湖泊环境的时间变化是有用的。