Riverine influence on nitrogen fixation in the upwelling region off Vietnam, South China Sea
Riverine influence on nitrogen fixation in the upwelling region off Vietnam, South China Sea
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DOI：
10.1029/2005gl025569
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发表时间：
2006-04
影响因子：
5.2
通讯作者：
M. Voss;Deniz Bombar;N. Loick;J. Dippner
中科院分区：
文献类型：
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作者：
M. Voss;Deniz Bombar;N. Loick;J. Dippner
固氮被认为在海洋贫营养亚热带区域最为重要。在这里，我们表明固氮作用在越南附近的上升流区域也很明显。我们比较了季风季节和季风间的固氮率和其他水化学变量，发现固氮率相当。季风季节期间高出 10 倍。然而，在实际的上升流区域——沿着海岸的 40-50 公里宽的地带——情况并非如此，而是在离岸更远的地方，湄公河羽流很明显。因此，我们假设湄公河羽流中水柱、微量营养素和/或微量金属的稳定性可能是蓝藻生长增强的原因。这些蓝细菌可能是Trichodesmium、单细胞或硅藻相关的共生体，后者来自亚马逊等其他河流羽流。
Nitrogen fixation is assumed to be most important in oligotrophic subtropical regions of the oceans. Here we show that nitrogen fixation can also be pronounced in the upwelling region off Vietnam. We compare nitrogen fixation rates and other hydro‐chemical variables from the monsoon season with the intermonsoon season and find that nitrogen fixation rates are app. 10 times higher during the monsoon season. However, this was not the case in the actual upwelling region – a 40–50 km wide strip along the coast – but further offshore, where the Mekong plume was noticeable. Therefore, we hypothesize that the stability of the water column, micronutrients and/or trace metals in the Mekong river plume may be responsible for enhanced cyanobacterial growth. These cyanobacteria may be either Trichodesmium, unicellular, or diatom‐associated symbionts, the latter are known from other river plumes like the Amazon.