The aim of this study was to decouple and quantify the influence of various biological and physical processes on the structure and variability of the marine carbonate system in the surface waters of the eastern part of the Fram Strait area. This productive region is characterized by its complex hydrographic and sea ice dynamics, providing an ideal set up to study their influence on the variability of the marine carbonate system. Different variables of the marine CO2 system: Total Alkalinity (TA), Dissolved Inorganic Carbon (DIC), partial pressure of CO2 (pCO2), and pH, were analysed together with temperature, salinity, sea ice extension, and chlorophyll a distribution during three consecutive summers (2019, 2020 and 2021), each of them having a unique oceanographic setting. The data revealed that TA and DIC are mostly controlled by the mixing of Atlantic water and sea ice meltwater. The combined effects of organic matter production/remineralization, calcium carbonate precipitation/dissolution, and air/sea CO2 gas exchange cause deviations from this salinity-related mixing. The scale of these deviations and the proportion between the effects observed for TA and DIC suggest interannual shifts in net primary production and dominant phytoplankton species in the area. These shifts are correlated with the sea ice extent and the spread of the Polar Surface Waters in the region. Net primary production is the main factor controlling the temporal and spatial variability of pH and pCO2 in the study area followed by the influence of temperature and, mixing of water masses expressed with salinity (seawater freshening). Surface waters of the Fram Strait area were generally undersaturated in CO2. The lowest pCO2 values, coinciding with an increase in oxygen saturation, were observed in areas of mixing of Arctic and Atlantic-derived water masses. However, as shown for 2021, a reduction of the sea ice extent may induce a westward shift of the chlorophyll maximum, resulting in pCO2 increase and pH decrease in the eastern part. This indicates that sea ice extent and associated spread of Polar Surface Waters may be important factors shaping primary production, and thus pCO2 and pH, in the Fram Strait area.

中文翻译：

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控制弗拉姆海峡表层水域夏季海洋 CO2 系统变化的关键过程


本研究的目的是解耦和量化各种生物和物理过程对弗拉姆海峡地区东部表层水域海相碳酸盐系统结构和可变性的影响。这个多产区的特点是其复杂的水文和海冰动力学，为研究它们对海洋碳酸盐系统变化的影响提供了理想的设置。分析了海洋 CO2 系统的不同变量：总碱度 （TA）、溶解无机碳 （DIC）、CO2 分压 （pCO2） 和 pH 值，以及连续三个夏季（2019 年、2020 年和 2021 年）的温度、盐度、海冰延伸和叶绿素 a 分布，每个夏季都有独特的海洋学环境。数据显示，TA 和 DIC 主要受大西洋水和海冰融水混合控制。有机物产生/再矿化、碳酸钙沉淀/溶解和空气/海洋 CO2 气体交换的综合效应导致偏离这种与盐度相关的混合。这些偏差的规模以及观察到的 TA 和 DIC 效应之间的比例表明，该地区净初级生产和主要浮游植物物种的年际变化。这些变化与该地区的海冰范围和极地表层水的扩散有关。净初级产量是控制研究区 pH 和 pCO2 时间和空间变化的主要因素，其次是温度和以盐度表示的水团混合（海水清新）的影响。弗拉姆海峡地区的表层水通常缺乏 CO2 饱和。 在北极和大西洋衍生的水团混合区域观察到最低的 pCO2 值，同时氧饱和度的增加。然而，正如 2021 年所示，海冰面积的减少可能会导致叶绿素最大值向西移动，从而导致东部的 pCO2 增加和 pH 值降低。这表明海冰范围和极地表层水的相关扩散可能是影响弗拉姆海峡地区初级生产的重要因素，从而影响 pCO2 和 pH 值。