In this paper we investigate the spatial extent and biogeochemical properties of a known CO₂ plume using the pelagic transport-biogeochemical model BROM (Bottom RedOx Model). The model consists of a biogeochemical module, a 2-dimensional vertical transport module and gas bubble fate module, parameterizing bubbles rising and dissolution according to existing approaches. A controlled CO₂ release experiment was carried out in the Horten Inner Harbor, Norway, in September 2018. This isolated bay is characterized by limited water mixing and anoxia in the bottom layer. CO₂ was released at a water depth of 18 m either in a gas phase or dissolved in seawater at leak rates ranging from 0.1 l/min to 15.8 l/min. The chemical response to the release events relative to background variations was measured using chemical sensors mounted on two seabed templates located 4 m and 15 m from the release point, respectively, and compared to the values predicted by the model. The measurements show elevated levels of pCO₂ and simultaneously decreased values in pH corresponding to the controlled release experiments. The model's simulations were in good agreement with the baseline observations and the measured changes forced by the experimental leak. The model predicts that after a continuous leak of this magnitude in stagnant conditions of anoxic bottom water, a 2–3 weeks long restoration period occurs, after which the disturbances disappear. This work confirms that the footprint of a potential CO₂ leak is localized in the vicinity of the source (tens of meters) where it can be detectable with available chemical sensors.

在本文中，我们使用远洋运输-生物地球化学模型 BROM（底部氧化还原模型）研究了已知 CO ₂羽流的空间范围和生物地球化学特性。该模型由生物地球化学模块、二维垂直输运模块和气泡命运模块组成，根据现有方法参数化气泡上升和溶解。2018 年 9 月，在挪威的霍滕内港进行了受控 CO ₂释放实验。这个孤立的海湾的特点是水混合有限，底层缺氧。CO ₂在 18 m 水深处以气相或溶解在海水中以 0.1 l/min 至 15.8 l/min 的泄漏率释放。使用分别安装在离释放点 4 m 和 15 m 的两个海底模板上的化学传感器测量相对于背景变化的释放事件的化学响应，并与模型预测的值进行比较。测量结果显示 pCO ₂水平升高并同时降低与控释实验相对应的 pH 值。该模型的模拟与基线观察结果和实验泄漏造成的测量变化非常吻合。该模型预测，在缺氧底水的停滞条件下连续发生如此严重的泄漏后，将出现 2-3 周长的恢复期，之后扰动消失。这项工作证实了潜在的 CO ₂泄漏的足迹位于源附近（数十米），可以用可用的化学传感器检测到。