Silicon uptake and supply during a Southern Ocean iron fertilization experiment (EIFEX) tracked by Si isotopes
Silicon uptake and supply during a Southern Ocean iron fertilization experiment (EIFEX) tracked by Si isotopes
复制标题
由硅同位素追踪的南大洋铁施肥实验 (EIFEX) 期间硅的吸收和供应
DOI：
--
复制
发表时间：
2011
期刊：
影响因子：
--
通讯作者：
D. Cardinal
中科院分区：
文献类型：
--
作者：
A. Cavagna;F. Fripiat;F. Dehairs;D. Wolf;B. Cisewski;N. Savoye;L. André;D. Cardinal
研究了在南大洋（SO）涡旋中，由铁施肥实验引起的硅藻水华期间溶解硅（δ30SiDSi）和生物硅（δ30SiBSi）同位素组成的演化。溶解硅（DSi）的消耗量明显增加，作为一个结果，铁的添加。我们估计表观Si同位素分馏因子为21.36% ± 0.11%，与基于在充满铁的条件下体外孵育的估计值无显著差异，并且与先前在缺铁条件下的SO研究一致。δ 30 SiSi的时间变化最好将施肥表层沃茨视为一个开放系统，即，DSi由冬季水连续供应。使用垂直扩散率，我们估计供应量为6.7 ± 1.2 mmol Si m−2 d−1，占DSi总需求的30% ± 5%。我们估计生物硅（BSi）的产量为22.1 ± 1.8 mmol Si m−2 d−1，与SO中自然条件下的BSi产量相似。在施肥开始之前的DSi使用保守估计为49% ± 4%，并且由于Fe施肥，初始DSi储库的另外31% ± 4%被消耗。BSi输出量估计为17.4 ± 1.7 mmol Si m−2 d−1。我们的研究结果表明，在这项研究中，三个主要过程对δ30SiSi特征，生物吸收，来自地下的Si供应和BSi的输出起着重要作用，并且在这样的铁施肥实验中，生产和输出的幅度与南大洋发生的天然硅藻水华相似。
We studied the evolution of the isotopic composition of dissolved Si (δ30SiDSi) and biogenic Si (δ30SiBSi) during a diatom bloom induced by an iron fertilization experiment in a Southern Ocean (SO) eddy. Dissolved Si (DSi) consumption was clearly boosted as a result of iron addition. We estimate an apparent Si isotopic fractionation factor of 21.36% ± 0.11%, not significantly different from estimates based on in vitro incubations under Fe‐replete conditions and in agreement with previous SO studies under Fe‐depleted conditions. The temporal variations of the δ30SiSi are best reconstructed considering the fertilized surface waters as an open system, i.e., DSi is continuously supplied from the winter water. Using vertical diffusivity, we estimate a supply of 6.7 ± 1.2 mmol Si m−2 d−1 representing 30% ± 5% of total DSi demand. We estimate biogenic silica (BSi) production at 22.1 ± 1.8 mmol Si m−2 d−1, similar to BSi production under natural conditions in the SO. The DSi use preceding the start of the fertilization was conservatively estimated at 49% ± 4%, and as a result of the Fe‐fertilization, a further 31% ± 4% of the initial DSi reservoir was consumed. The BSi export was estimated to be 17.4 ± 1.7 mmol Si m−2 d−1. Our results suggest that for this study three main processes were acting significantly on δ30SiSi signatures, biological uptake, Si supply from subsurface, and export of BSi, and that the magnitude of production and export in such a Fe‐fertilized experiment are similar to those for natural diatom blooms occurring in the Southern Ocean.