Leveraging Artificial\nOxygenation Efficacy for Coastal\nHypoxia by Taking Advantage of Local Hydrodynamics

This study evaluates deployment strategies for artificial\noxygenation\ndevices to mitigate coastal hypoxia, particularly in mariculture regions.\nFocusing on a typical mariculture region in the coastal waters of\nChina, we examined the combined effects of topography, hydrodynamics,\nand biogeochemical processes. A high-resolution three-dimensional\nphysical–biogeochemical coupled model, validated against observational\ndata from three summer cruises in 2020, accurately captured key drivers\nof hypoxia. Results reveal that hypoxic zones exhibit an uneven distribution,\ndriven by persistent offshore jets at specific locations. Nearshore\ndeployment of oxygenation devices upstream of hypoxic zones significantly\nimproves oxygen delivery and is more cost-efficient due to reduced\nconstruction and maintenance requirements. Uncertainty analysis explored\nthe impacts of varying water mass properties, oxygen concentration,\ninjection flow rates, and biogeochemical content. The influence varies\ndepending on the deployment site. Particularly, buoyant plumes can\nnotably reduce the effectiveness of hypoxia mitigation. Artificial\noxygenation may lead to unintended ecological impacts, including increased\nnutrient release and enhanced primary production, which can prolong\nthe duration of hypoxia. Furthermore, simulations indicate that natural\ndownwelling currents are insufficient to transport oxygen-enriched\nsurface water to the bottom hypoxic zones. These findings underscore\nthe importance of comprehensive predeployment assessments and the\nadvancement of oxygenation technologies to ensure both immediate effectiveness\nand long-term ecological sustainability.