The western Arctic Ocean, including its shelves and coastal habitats, has become a focus in ocean acidification research over the past decade as the colder waters of the region and the reduction of sea ice appear to promote the uptake of excess atmospheric CO₂. Due to seasonal sea ice coverage, high-frequency monitoring of pH or other carbonate chemistry parameters is typically limited to infrequent ship-based transects during ice-free summers. This approach has failed to capture year-round nearshore carbonate chemistry dynamics which is modulated by biological metabolism in response to abundant allochthonous organic matter to the narrow shelf of the Beaufort Sea and adjacent regions. The coastline of the Beaufort Sea comprises a series of lagoons that account for > 50 % of the land–sea interface. The lagoon ecosystems are novel features that cycle between “open” and “closed” phases (i.e., ice-free and ice-covered, respectively). In this study, we collected high-frequency pH, salinity, temperature, and photosynthetically active radiation (PAR) measurements in association with the Beaufort Lagoon Ecosystems – Long Term Ecological Research program – for an entire calendar year in Kaktovik Lagoon, Alaska, USA, capturing two open-water phases and one closed phase. Hourly pH variability during the open-water phases are some of the fastest rates reported, exceeding 0.4 units. Baseline pH varied substantially between the open phase in 2018 and open phase in 2019 from ∼ 7.85 to 8.05, respectively, despite similar hourly rates of change. Salinity–pH relationships were mixed during all three phases, displaying no correlation in the 2018 open phase, a negative correlation in the 2018/19 closed phase, and a positive correlation during the 2019 open phase. The high frequency of pH variability could partially be explained by photosynthesis–respiration cycles as correlation coefficients between daily average pH and PAR were 0.46 and 0.64 for 2018 and 2019 open phases, respectively. The estimated annual daily average CO₂ efflux (from sea to atmosphere) was 5.9 ± 19.3 $\mathrm{mmol}{\mathrm{m}}^{-\mathrm{2}}{\mathrm{d}}^{-\mathrm{1}}$, which is converse to the negative influx of CO₂ estimated for the coastal Beaufort Sea despite exhibiting extreme variability. Considering the geomorphic differences such as depth and enclosure in Beaufort Sea lagoons, further investigation is needed to assess whether there are periods of the open phase in which lagoons are sources of carbon to the atmosphere, potentially offsetting the predicted sink capacity of the greater Beaufort Sea.

中文翻译：

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北极泻湖的季节阶段揭示了海-气界面处pH变异性和CO ₂通量的不连续性

在过去的十年中，北冰洋西部地区（包括其大陆架和沿海生境）已经成为海洋酸化研究的重点，因为该地区较冷的水域和海冰的减少似乎促进了过量大气中CO ₂的吸收。由于季节性的海冰覆盖，通常在无冰夏季，高频监测pH值或其他碳酸盐化学参数通常仅限于基于船的样带。这种方法未能捕捉到全年的近岸碳酸盐化学动力学，而这种动力学是由生物代谢调节的，它是对波弗特海及其邻近地区狭窄的陆架上丰富的异源有机物的响应。博福特海的海岸线包括一系列泻湖，占 > 50％的陆海界面。泻湖生态系统是新颖的特征，可在“开放”和“封闭”阶段（即分别为无冰和覆冰）之间循环。在这项研究中，我们结合了Beaufort Lagoon生态系统（长期生态研究计划），在美国阿拉斯加的Kaktovik Lagoon，收集了高频pH，盐度，温度和光合有效辐射（PAR）的测量值，捕获两个开放水相和一个封闭相。在开放水域，pH值的每小时变化是一些最快的速度，超过0.4个单位。基线pH在2018年的开放相和2019年的开放相之间从〜 尽管每小时的变化率相似，但仍分别为7.85至8.05。在所有三个阶段中，盐度-pH关系是混合的，在2018年开放阶段没有相关性，在2018/19年封闭阶段是负相关，在2019年开放阶段是正相关。pH变异性的高频率可以部分通过光合作用-呼吸周期来解释，因为2018年和2019年开放期的日平均pH和PAR之间的相关系数分别为0.46和0.64。估计每年从海洋到大气的年平均CO ₂外排量为5.9  ±  19.3 $\mathrm{毫摩尔}{\mathrm{米}}^{--\mathrm{2}}{\mathrm{d}}^{--\mathrm{1个}}$，尽管表现出极大的可变性，但与沿海波弗特海地区估计的CO ₂负流入相反。考虑到博福特海泻湖的地貌差异（例如深度和围封性），需要进一步调查以评估是否存在开放阶段的时期，泻湖是大气中碳的来源，有可能抵消大博福特海的预计汇入量。