Silica cycling and isotopic composition in northern Marguerite Bay on the rapidly-warming western Antarctic Peninsula
Silica cycling and isotopic composition in northern Marguerite Bay on the rapidly-warming western Antarctic Peninsula
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DOI：
10.1016/j.dsr2.2016.09.006
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发表时间：
2017-05-01
影响因子：
3
通讯作者：
Ganeshram, Raja S.
中科院分区：
文献类型：
--
作者：
Annett, Amber L.;Henley, Sian F.;Ganeshram, Raja S.
南大洋是硅（Si）循环的关键区域，这里建立的同位素特征影响着世界其他海洋。南大洋的气候和生态系统正在迅速变化，有可能影响硅循环和同位素动力学。本文研究了南极西部半岛（WAP）沿海地区溶解硅浓度和同位素特征、颗粒硅浓度和硅藻物种形成的高分辨率时间序列数据集，以揭示硅循环中生产力和硅藻组合变化的相关性。溶解和颗粒硅相反映了生物吸收的主导控制，并结合同位素分馏与低/中等生产力的季节是一致的。生源硅是紧密耦合到叶绿素和颗粒有机碳在采样点，符合浮游植物占主导地位的组合沿着WAP。硅藻物种的变异性对地表沃茨中溶解硅的同位素特征的影响可以忽略不计，尽管由于硅藻物种的差异溶解，这不太可能适用于沉积物。硅藻生产力沿着WAP的持续下降可能会导致未使用的硅库存增加，这可能会反馈到硅有限的地区，促进硅藻生长和碳减少更远。
The Southern Ocean is a key region for silica (Si) cycling, and the isotopic signatures established here influence the rest of the world's oceans. The climate and ecosystem of the Southern Ocean are changing rapidly, with the potential to impact Si cycling and isotope dynamics. This study examines high-resolution time-series dataset of dissolved Si concentrations and isotopic signatures, particulate Si concentrations and diatom speciation at a coastal site on the western Antarctic Peninsula (WAP), in order to characterise changes in Si cycling with respect to changes occurring in productivity and diatom assemblages. Dissolved and particulate Si phases reflect the dominant control of biological uptake, and combined with isotopic fractionation were consistent with a season of low/intermediate productivity. Biogenic Si is tightly coupled to both chlorophyll and particulate organic carbon at the sampling site, consistent with diatom-dominated phytoplankton assemblages along the WAP. Variability in diatom speciation has a negligible impact on the isotopic signature of dissolved Si in surface waters, although this is unlikely to hold for sediments due to differential dissolution of diatom species. A continued decline in diatom productivity along the WAP would likely result in an increasing unused Si inventory, which can potentially feed back into Si-limited areas, promoting diatom growth and carbon drawdown further afield.