Role of particle stock and phytoplankton community structure in regulating particulate organic carbon export in a large marginal sea
Role of particle stock and phytoplankton community structure in regulating particulate organic carbon export in a large marginal sea
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颗粒库和浮游植物群落结构在调节大型边缘海颗粒有机碳输出中的作用
DOI：
10.1002/2014jc010432
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发表时间：
2015-03-01
影响因子：
3.6
通讯作者：
Dai, Minhan
中科院分区：
文献类型：
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作者：
Cai, Pinghe;Zhao, Daochen;Dai, Minhan
在这项研究中，我们利用234/238U不平衡来确定南中国海真光层中颗粒有机碳(POC)的输出。从2009年8月到2011年5月，在四个航次中收集了234、总叶绿素、色素和POC的深度剖面，覆盖了春季、夏季、秋季和冬季的整个季节周期。所获得的大量数据集使人们能够评估上层海洋POC出口的季节变化及其在大型边缘海的控制情况。结果表明，对于海岸、陆架和盆地，真光层的234通量分别落在528DPM 1550、340DPM 2694和302-2647DPM m−2d−1之间。在这些区域中，真光区底部的POC/234比值分别在5.7-5 8.2、4.6-44.0和2.5-15.5μmolDPM−1范围内下降。相应地，对于沿海、陆架和盆地区域，真光层的POC平均输出通量分别为24.3mmolCm−2d−1和6.3mmolCm 2d Mf1。研究区POC出口通量的季节变化明显，且出口高峰期一般在秋季。我们使用一种简单的线性回归(LLS)方法来检验POC出口与POC储量以及浮游生物群落结构之间的相关性。我们发现POC输出通量与近岸海域硅藻含量之间存在很强的相关性(R2 = 0.73，p <； 0.005)，表明本省POC输出通量主要受大型浮游植物，特别是硅藻的驱动。在陆架区域，POC出口通量与真光区POC存量之间存在较强的相关性(R2 = 0.54，p <； 0.0001)。这表明南中国陆架的POC出口通量主要受POC存量的控制。相比之下，在南中国海盆，我们发现POC输出通量与典型的<； = 5μm的浮游植物和原生植物的比例之间存在着微弱但有趣的相关性(r2；0.26，p <； 0.0001)。这表明南中国海盆POC输出通量的控制机制是复杂的。然而，小型浮游植物可能在控制POC输出通量方面发挥重要作用，因为它们在该地区的浮游植物群落结构中占据主导地位。
In this study, we utilize 234Th/238U disequilibrium to determine particulate organic carbon (POC) export from the euphotic zone in the South China Sea. Depth profiles of 234Th, total chlorophyll, pigments, and POC were collected during four cruises from August 2009 to May 2011, covering an entire seasonal cycle of spring, summer, autumn, and winter. The extensive data set that was acquired allows for an evaluation of the seasonal variability of upper ocean POC export and its controls in a large marginal sea. The results show that 234Th fluxes from the euphotic zone fall in the range of 528−1550, 340−2694, and 302–2647 dpm m−2 d−1 for the coastal, shelf, and basin regimes, respectively. In these regimes, POC/234Th ratios at the base of the euphotic zone fall in the range of 5.7–58.2, 4.6–44.0, and 2.5–15.5 μmol dpm−1, respectively. Accordingly, for the coastal, shelf, and basin regimes, the mean POC export fluxes from the euphotic zone are 24.3, 18.3, and 6.3 mmolC m−2 d−1, respectively. Seasonal variations in POC export flux are remarkable in the study area, and POC export peaks were generally observed in autumn. We use a simple linear regression (LLS) method to examine the correlation of POC export versus POC stock and versus plankton community structure. We found a strong correlation (R2 = 0.73, p < 0.005) between POC export flux and the fraction of diatom in the coastal area, indicating that POC export flux in this province is driven by large phytoplankton, in particular, diatoms. In the shelf area, a relatively strong correlation (R2 = 0.54, p < 0.0001) was noted for POC export flux and POC stock in the euphotic zone. This indicates that POC export flux in the South China Sea shelf is primarily controlled by POC stock. In contrast, in the South China Sea basin, we identified a weak but intriguing correlation (R2 = 0.26, p < 0.0001) between POC export flux and the fraction of haptophytes and prasinophytes that are typically < 5 μm in size. This suggests that mechanisms controlling POC export flux in the South China Sea basin are complicated. However, small phytoplankton may play a significant role in controlling POC export flux since they dominate the phytoplankton community structure in this region.