The seasonal cycle of carbonate system processes in Ryder Bay, West Antarctic Peninsula
The seasonal cycle of carbonate system processes in Ryder Bay, West Antarctic Peninsula
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DOI：
10.1016/j.dsr2.2016.11.006
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发表时间：
2017-05-01
影响因子：
3
通讯作者：
Johnson, Martin T.
中科院分区：
文献类型：
--
作者：
Legge, Oliver J.;Bakker, Dorothee C. E.;Johnson, Martin T.
由于缺乏观测数据和系统的复杂性，对季节性海冰覆盖的沃茨的碳循环仍然知之甚少。在这里，我们提出了三个连续的季节性周期的上层海洋溶解无机碳（DIC）和总碱度测量从莱德湾在南极西部半岛。我们把观测到的DIC变化归因于四个过程：水团的混合、海气CO2通量、碳酸钙沉淀/溶解和光合作用/呼吸。这种方法使我们能够解决季节性DIC循环的主要驱动因素，并调查碳酸盐系统年际变化背后的机制。我们观察到一个强大的，不对称的季节性循环的碳酸盐系统，由物理过程和初级生产驱动。在夏季，冰川和海冰融化，与深层水混合减少，降低了表面沃茨中DIC的浓度。影响碳酸盐系统的主要过程是净光合作用，它减少了DIC和CO2的逸度，使海洋成为大气CO2的净汇。在冬季，混合更深，富碳水和净异养增加表面DIC浓度，导致pH值低至7.95和文石饱和状态接近1。我们没有观察到明确的碳酸钙沉淀/溶解的季节性周期，但碳酸盐时间序列的一些短暂的功能强烈表明，在海湾中确实发生了显着的碳酸钙沉淀。在这项研究中观察到的变化表明，在混合和海冰覆盖的变化显着影响碳循环在这个动态环境。保持这一独特的时间序列将有助于更好地了解季节性海冰覆盖的沃茨中的碳酸盐系统。
The carbon cycle in seasonally sea-ice covered waters remains poorly understood due to both a lack of observational data and the complexity of the system. Here we present three consecutive seasonal cycles of upper ocean dissolved inorganic carbon (DIC) and total alkalinity measurements from Ryder Bay on the West Antarctic Peninsula. We attribute the observed changes in DIC to four processes: mixing of water masses, air-sea CO2 flux, calcium carbonate precipitation/dissolution and photosynthesis/respiration. This approach enables us to resolve the main drivers of the seasonal DIC cycle and also investigate the mechanisms behind interannual variability in the carbonate system. We observe a strong, asymmetric seasonal cycle in the carbonate system, driven by physical processes and primary production. In summer, melting glacial ice and sea ice and a reduction in mixing with deeper water reduce the concentration of DIC in surface waters. The dominant process affecting the carbonate system is net photosynthesis which reduces DIC and the fugacity of CO2, making the ocean a net sink of atmospheric CO2. In winter, mixing with deeper, carbon-rich water and net heterotrophy increase surface DIC concentrations, resulting in pH as low as 7.95 and aragonite saturation states close to 1. We observe no clear seasonal cycle of calcium carbonate precipitation/dissolution but some short-lived features of the carbonate time series strongly suggest that significant precipitation of calcium carbonate does occur in the Bay. The variability observed in this study demonstrates that changes in mixing and sea-ice cover significantly affect carbon cycling in this dynamic environment. Maintaining this unique time series will allow the carbonate system in seasonally sea-ice covered waters to be better understood.