夏季台湾海峡南部海域上层水体的生物固氮作用

Abstract

PDF HTML阅读 XML下载 导出引用 引用提醒 夏季台湾海峡南部海域上层水体的生物固氮作用 DOI: 10.5846/stxb201305101009 作者: 作者单位: 厦门大学海洋与地球学院,厦门大学海洋与地球学院,厦门大学海洋与地球学院,厦门大学海洋与地球学院,厦门大学海洋与地球学院,厦门大学海洋与地球学院,厦门大学海洋与地球学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目(41125020,41076043,41206062);国际海域资源调查与开发"十二五"项目(DY125-13-E-01) Biological nitrogen fixation in the upper water column in the south Taiwan Strait during summer 2011 Author: Affiliation: College of Ocean and Earth Sciences,Xiamen University,College of Ocean and Earth Sciences,Xiamen University,College of Ocean and Earth Sciences,Xiamen University,College of Ocean and Earth Sciences,Xiamen University,College of Ocean and Earth Sciences,Xiamen University,College of Ocean and Earth Sciences,Xiamen University,College of Ocean and Earth Sciences,Xiamen University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:2011年6-7月,利用15N2示踪法实测了台湾海峡南部海域的生物固氮速率,结合温度、盐度、天然颗粒物氮同位素组成的分布,分析并讨论了影响研究海域生物固氮速率的环境因素。结果表明,夏季台湾海峡南部海域的生物固氮速率介于 168-1080 nmol m-3 d-1之间,平均为537 nmol m-3 d-1,较高的生物固氮速率大多出现在次表层水体中。研究站位的积分固氮速率变化范围为11-40 μmol m-2 d-1,平均为23 μmol m-2 d-1。积分固氮速率的空间变化与不同水团的影响有关,在受黑潮水影响的海域,生物固氮速率较高,而在上升流和受河流冲淡水影响的海域,生物固氮速率较低,说明较低的水温及较高的无机氮营养盐可能会抑制研究海域的生物固氮作用。研究海域天然颗粒物δ15N与生物固氮速率之间呈现良好的负相关关系,表明天然颗粒物氮同位素组成可定性指征研究海域生物固氮作用的强弱。 Abstract:Biological N2 fixation in marine environments is a major component in the ocean nitrogen budget and plays an important role in global carbon cycles through the sequestration of atmospheric carbon dioxide and production of marine organic matter. N2 fixation could be regulated by the abundance and chemical speciation of nutrients and many trace elements in seawater. Recent studies have revealed that N2 fixation is much more widespread in marine environments than previously thought. However, little is known about the N2 fixation in the Taiwan Strait, especially on N2 fixation rates, and their relationship with environmental parameters. The major objectives of this study were to determine the N2 fixation rates and their spatial distributions and to explore major physicochemical controlling factors in the south Taiwan Strait. During June and July 2011, seawater samples were collected from ten stations at two transects in the south Taiwan Strait for the measurements of N2 fixation rate using the 15N2 tracer assay. Particulate nitrogen and its isotopic composition were measured with an elemental analyzer (Carlo Erba NC 2500) coupled with a Finnigan MAT Deltaplus XP isotope ratio mass spectrometer. Reproducibility of nitrogen isotope measurements (in terms of δ15N) was within 0.2‰. Our results showed that N2 fixation rates in the south Taiwan Strait ranged from 168-1080 nmol m-3 d-1 with an average of 537 nmol m-3 d-1. Most of the high rates were observed at subsurface layers. The depth-integrated N2 fixation rates were 11-40 μmol m-2 d-1 with an average of (23±10) μmol m-2 d-1. The distribution of the N2 fixation rates showed regional variations with influence from water masses with distinctive temperature and salinity. Higher N2 fixation rates were mostly observed in the regions influenced by the Kuroshio, with an average of 31 μmol m-2 d-1, while lower rates occurred in the upwelling and river plume regions with an average of 15 μmol m-2 d-1. This spatial distribution pattern indicated that biological N2 fixation was largely impeded by the low temperature and the high concentration of dissolved inorganic nitrogen in the south Taiwan Strait. The contribution of N2 fixation in the study area could be further quantified based on the δ15N signatures of suspended particles which could be significantly depleted during N2 fixation. Indeed, a negative correlation between the δ15N signatures of suspended particles and N2 fixation rates was observed regardless of using all data points or depth-averaged values within the water column. This indicated that 15N-depleted particles were largely derived from the enhanced N2 fixation, supporting the use of nitrogen isotopic composition (δ15N) of suspended particles as a potential indicator of N2 fixation in the south Taiwan Strait. Further studies are needed to better elucidate the relationship between N2 fixation rates and limiting elements and their chemical speciation, and thus the physical and biogeochemical controls on N2 fixation in the south Taiwan Strait. 参考文献 相似文献 引证文献