东沙海域沉积物有机碳、氮含量及其同位素分布特征对富甲烷环境指示意义  

Carbon and Nitrogen Concentration and Stable Isotopic Composition of Sediments from Dongsha Area to Indicator of Methane-rich Environment

作　　者：曹超[1] 雷怀彦[1] 官宝聪[2] 柳浩然[1] 吴丽芳[1] 

机构地区：[1]厦门大学海洋与环境学院,近海海洋环境科学国家重点实验室,福建厦门361005 [2]国家海洋局第三海洋研究所,福建厦门361005

出　　处：《厦门大学学报（自然科学版）》2010年第6期838-844,共7页Journal of Xiamen University：Natural Science

基　　金：“973”计划(2009CB219501);国家自然科学基金资助项目(40976035)

摘　　要：我国东沙海域是天然气水合物的潜在区,是目前世界上有机碳、氮同位素的环境效应研究的热点区域.通过对ODP184航次3个站位101件沉积物样品中的有机碳、氮含量,碳、氮同位素组成及碳/氮质量比分析测定,并结合沉积物中的顶空甲烷气体浓度和间隙水的盐度、SO42-、NH4+浓度分析,结果显示:1146站位430 m以下沉积层为富甲烷环境,该层段有机质1δ3C和1δ5N值变重,同时碳/氮质量比变小,表明沉积物母质主要来源于陆源高等植物,而1144和1148站位沉积物母质主要来源于海洋浮游动植物;沉积物中氮含量的增加和1δ5N值的亏损,推断可能与富甲烷环境中古细菌硝化作用和固氮作用有关;沉积物中碳、氮同位素的分布与有机碳、氮含量的规律相一致,也反映沉积物间隙水中相关离子的变化趋势.Dongsha sea area of China is a potential natural gas hydrate zone,and is also the hotspot region for the research of organic carbon and nitrogen isotopic environmental effect in the world.Through the measurement of organic carbon and nitrogen contents,carbon and nitrogen isotopes composition,m（C）∶m（N）,and the analysis of methane gas concentration,pore water salinity,c（SO42-）and c（NH4＋） in 101 sediments samples collected by ODP184 leg,it was demonstrated that illuvial horizon below 430 m displayed as methane-rich environment in 1146 site.The increase of δ13C and δ15N values in organic matter and the decreases of m（C）∶m（N） in the illuvial horizon below 430 m indicates that sedimentary parent materials come mainly from terrestrial higher plants,however,sedimentary mother materials in 1144 and 1148 sites come mainly from marine zooplankton and phytoplankton.From the increase of nitrogen content and δ15N value losses in sediments it can be inferred that methane-rich environment forming is related to nitrification and nitrogen fixation.Carbon and nitrogen isotope distribution is consistent with magnitude of organic carbon and nitrogen content in sediments,which reflects the tendency of pore water-related ions change.

关 键 词：东沙海域 有机碳、氮同位素 富甲烷环境 指示意义 

分 类 号：P736.4[天文地球—海洋地质]