The biogeochemical dynamics of fjords in the southeastern Pacific Ocean are strongly influenced by hydrological and oceanographic processes occurring at a seasonal scale. In this study, we describe the role of hydrographic forcing on the seasonal variability of the carbonate system of the Sub-Antarctic glacial fjord, Seno Ballena, in the Strait of Magellan (53°S). Biogeochemical variables were measured in 2018 during three seasonal hydrographic cruises (fall, winter and spring) and from a high-frequency pCO₂-pH mooring for 10 months at 10 ± 1 m depth in the fjord. The hydrographic data showed that freshwater input from the glacier influenced the adjacent surface layer of the fjord and forced the development of undersaturated CO₂ (< 400 μatm) and low aragonite saturation state (Ω_Ar < 1) water. During spring, the surface water had relatively low pCO₂ (mean = 365, range: 167 - 471 μatm), high pH (mean = 8.1 on the total proton concentration scale, range: 8.0 - 8.3), and high Ω_Ar (mean = 1.6, range: 1.3 - 4.0). Concurrent measurements of phytoplankton biomass and nutrient conditions during spring indicated that the periods of lower pCO₂ values corresponded to higher phytoplankton photosynthesis rates, resulting from autochthonous nutrient input and vertical mixing. In contrast, higher values of pCO₂ (range: 365 – 433 μatm) and relatively lower values of pH_T (range: 8.0 – 8.1) and Ω_Ar (range: 0.9 – 2.0) were recorded in cold surface waters during winter and fall. The naturally low freshwater carbonate ion concentrations diluted the carbonate ion concentrations in seawater and decreased the calcium carbonate saturation of the fjord. In spring, at 10 m depth, higher primary productivity caused a relative increase in Ω_Ar and pH_T. Assuming global climate change will bring further glacier retreat and ocean acidification, this study represents important advances in our understanding of glacier meltwater processes on CO₂ dynamics in glacier–fjord systems.

太平洋东南部峡湾的生物地球化学动态受到季节性尺度的水文和海洋过程的强烈影响。在这项研究中，我们描述了水文强迫对麦哲伦海峡（53°S）中亚南极冰川峡湾 Seno Ballena 碳酸盐系统季节性变化的作用。生物地球化学变量在 2018 年的三个季节性水文航行（秋季、冬季和春季）期间进行了测量，并从高频pCO ₂ -pH 系泊在峡湾 10 ± 1 m 深度处 10 个月。水文数据表明，来自冰川的淡水输入影响了峡湾的相邻表层，并迫使欠饱和 CO ₂ (< 400 μatm) 和低文石饱和状态 (Ω _Ar < 1) 水的发展。春季，地表水相对较低pCO ₂（平均值 = 365，范围：167 - 471 μatm）、高 pH 值（在总质子浓度范围内平均值 = 8.1，范围：8.0 - 8.3）和高 Ω _Ar（平均值 = 1.6，范围：1.3 - 4.0） . 春季浮游植物生物量和养分条件的同时测量表明，较低的时期pCO ₂值对应于较高的浮游植物光合作用速率，这是由于本土养分输入和垂直混合造成的。相比之下，较高的值p在冬季和秋季，在寒冷的地表水中记录到CO ₂（范围：365 – 433 μatm）和相对较低的 pH _T值（范围：8.0 – 8.1）和 Ω _{Ar （范围：0.9 – 2.0）。}天然低淡水碳酸根离子浓度稀释了海水中的碳酸根离子浓度并降低了峡湾的碳酸钙饱和度。在春季，在 10 m 深度，较高的初级生产力导致 Ω _Ar和 pH _T相对增加。_{假设全球气候变化将带来进一步的冰川退缩和海洋酸化，这项研究代表了我们对冰川-峡湾系统中 CO 2}动力学的冰川融水过程的理解的重要进展。