| 倪建宇,赵军,江巧文,姚旭莹.南海北部海域沉积物中生物钡、碳氮同位素的组成特征及其与表层水体初级生产之间的关系[J].海洋学报,2019,41(2):41-51 |
| 南海北部海域沉积物中生物钡、碳氮同位素的组成特征及其与表层水体初级生产之间的关系 |
| Biogenic barium, carbon and nitrogen isotopes features in sediments of the northern South China Sea and their correlation with primary productivity of surface ocean |
| 投稿时间：2018-03-28 修订日期：2018-06-29 |
| DOI：10.3969/j.issn.0253-4193.2019.02.004 |
| 中文关键词: 生物钡 有机质 碳氮同位素 生产力 南海北部 |
| 英文关键词:biogenic barium organic matter nitrogen and carbon isotopes primary productivity northern South China Sea |
| 基金项目:大洋矿产资源勘探开发专项基金项目（DY125-14-E-01）；国际合作项目"东亚大陆边缘现代地质过程与灾害机理"（GASI-GEOGE-05）。 |
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| 中文摘要: |
| 通过对采集自南海北部的D06和S0612两个短柱状沉积物样品中的不同赋存形态钡、有机碳和生物硅的含量以及有机质碳氮同位素组成的分析，结果表明沉积物中的钡主要以碎屑钡和自生的生物钡形式存在。沉积物中生物钡的含量在10.3~385.2 μg/g之间，平均值为177.0 μg/g，据此计算的新生产力在12.3~146.7 mg/（d·m2）（以碳计）之间，平均为78.9 mg/（d·m2）；D06站计算的结果和附近站位的实测值相当。沉积物中有机碳的含量在0.64%~1.34%之间，平均值为0.89%，C/N比值为4.96~5.93，平均值为5.54。有机碳的δ13C值在-22.98‰~-20.73‰之间，平均值为-21.46‰，依据端元组份同位素组成计算的陆源有机质比率显示，D06站位的有机质主要来自海洋生物，而S0612站位则受陆源有机质的影响较大。沉积物中有机质的δ15N值在3.96‰~6.29‰之间，平均值为5.26‰，反映的是该海区氮源的同位素组成，而不受硝酸盐利用率的影响。 |
| 英文摘要: |
| In this paper, we analyze different forms of barium, biogenic silica, the organic carbon (OC), total nitrogen concentrations and their stable isotopic compositions (δ13C and δ15N) in two short sediment cores sampled from the northern South China Sea (SCS). The results show that the detrital and biogenic barium are the main forms of barium in sediments. Based on the sequential extraction leaching, the biogenic barium content in sediments is between 10.3 μg/g and 385.2 μg/g with an average of 177.0 μg/g. Estimated the past productivity using the biogenic barium is between 12.3 mg/(d·m2) and 146.7 mg/(d·m2) with an average of 78.9 mg/(d·m2), and is comparable with the modern values near D06 station. The stratigraphic profiles of OC concentration, OC/TN ratios, δ13C and δ15N for the past about 400 years indicate that these two cores display distinctive histories. The δ13C values of sedimentary organic matter changed between -22.98‰ and -20.73‰. The relatively narrow δ13C range of sedimentary organic carbon with a mean value close to -21.46‰ indicates that the sedimentary organic matter is derived from marine phytoplankton mainly. Based on a two-end member mixing model, the estimated terrestrial organic matter is up to 41.3% at site S0612 and 11% at site D06 respectively. The δ15N values of sediments range from 5.92‰ to 6.29‰ with an average of (6.08±0.12)‰ for D06, and 3.96‰ to 4.85‰ with an average of (4.32±0.26)‰ for S0612 respectively. The low δ15N values may reflect that nitrogen fixation was more important for the new nitrogen supply and the source of ntritate from north Pacific intermediate water, and was not affected by nitrate utilization. |
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