Detectability of Alkalinity Plumes During the OAE Field Trial: A Bedford Basin Case Study

In the Fall of 2023, in collaboration with Dalhousie University researchers, Planetary Technologies completed a first-of-a-kind series of alkalinity releases in the Bedford Basin/Halifax Harbour (Canada) using several alkalinity sources at varying dosing rates. These OAE trials aimed to test the detectability of alkalinity plumes resulting from the addition of varying amounts of alkalinization material and the different types of material - dissolved or particulate. Detectability of the released alkalinity was examined by observing the changes in the carbonate system of seawater measured in the water samples and by the sensor-equipped in situ platforms - fixed and mobile – before, during and after the trials. The collected data was used to test and validate the regional biogeochemical model (ROMS) available for the Bedford Basin, which largely informed the sampling design during the trial.We will present the challenges encountered, results and insights gained during the field trials in the Bedford Basin/Halifax Harbour in the Fall of 2023, particularly focusing on improvements to the observational component in 2024. We will discuss the utility of the moored and profiling assets, surface and underwater vehicles, and various water sampling methods in tracking and characterizing alkalinity plumes during the OAE trials