Acidification in nearshore waters is influenced by a multitude of drivers that shape the dynamics of pH and carbonate chemistry variability on diurnal, seasonal, and yearly time scales. Monitoring efforts aimed at characterizing high temporal variability are lacking in many nearshore systems, particularly in high‐latitude regions such as Alaska. To rectify this, a nearshore acidification sensor array was established in the Fall of 2017 within Kachemak Bay, Alaska. Presented here are the results from the first year of these deployments, and the first record of a year‐long high‐frequency pH time series for nearshore Alaska. SeaFET™ pH and O₂ sensors deployed in Jakolof Bay and Bear Cove reveal a seasonally dynamic system in which nearshore waters in these two enclosed bays transition to being predominantly net autotrophic systems for a period of 60‐plus days. High rates and durations of primary production in late spring and early summer create high pH conditions and extreme variability. Observed pH values in Jakolof Bay and Bear Cove tracked hourly rates of change on the order of 0.18 and 0.10 units, respectively. In Jakolof Bay nondirectional variability within a 12‐h period was > 1 pH unit, exposing organisms to unstable, nonstatic pH conditions on tidal and diurnal cycles. Consistent frequency patterns detailing the magnitude of pH variability was correlated to tidal and O₂ signatures, elucidating the dynamics and drivers of pH variability. This first year of observations is the first step in quantifying the anthropogenic contribution to acidification for Kachemak Bay in the forthcoming years.

中文翻译：

---

季节性和生物强迫改变了北极亚拉斯加河口近岸pH极限的diel频率

近岸水域的酸化受到多种驱动因素的影响，这些驱动因素决定了日，季节和年度时间尺度上pH值和碳酸盐化学变化的动态。在许多近岸系统中，特别是在阿拉斯加等高纬度地区，都缺乏旨在表征高时变性的监测工作。为了解决这个问题，2017年秋季在阿拉斯加的Kachemak湾建立了近岸酸化传感器阵列。这里介绍的是这些部署第一年的结果，以及阿拉斯加近岸长达一年的高频pH时间序列的第一笔记录。SeaFET™pH和O ₂在Jakolof湾和Bear Cove中部署的传感器揭示了一个季节性动态系统，在这两个封闭的海湾中，近岸水域在长达60天以上的时间内转变为主要为净自养系统。春季末和初夏初产的高比率和持续时间造成了高pH条件和极端的可变性。在Jakolof湾和Bear Cove中观察到的pH值跟踪的每小时变化率分别为0.18和0.10单位。在Jakolof湾，在12小时内，非方向性变异大于1个pH单位，使生物体在潮汐和昼夜周期中处于不稳定，非静态的pH条件下。详细说明pH值变化幅度的一致频率模式与潮汐和O _2相关签名，阐明了pH可变性的动力学和驱动因素。第一年的观测结果是量化未来几年中人为化石湾酸化贡献的第一步。