[A-HW27] Biodiversity, nutrients and other materials in ecosystems from headwaters to coasts

[AHW27-19] The impacts of typhoon processes on marine dynamics and submarine groundwater discharge (SGD) in Zhanjiang Bay,China.

★Invited Papers

*Guangzhe Jin¹ (1.College of Ocean and Meteorology, Guangdong Ocean University, China)

Keywords:Typhoons, marine dynamics, submarine groundwater discharge, Zhanjiang Bay

Coastal oceans are highly responsive to typhoons, making them one of the most affected regions. However, our understanding of the impact of typhoon intensity and movement path on marine dynamic processes and eco-environmental factors remains limited because there are very few on-site investigations, especially continuous field observations in the bay during typhoon events. This study analyzed the seasonal fluctuations of seawater 222Rn in Zhanjiang Bay from June 2021 to March 2022 as well as combined dual water isotopes parameters through a continuous survey (with a 5-day interval) during ten cruises in Zhanjiang Bay, associated with two typhoons of varying intensities and landing tracks. Nutrients from SGD also showed seasonal fluctuations, and their annual input was comparable to that of rivers, significantly influencing the bay's trophic status. Freshwater contributions to nutrient loads increased significantly during typhoon periods, with a stronger typhoon showing a greater contribution. Typhoons led to a sharp increase in SGD flux, which lasted up to 15 days, nearly double the wet season background values. The highest SGD-driven fluxes of chemical constituents were estimated. After typhoons, water mass mixing intensified and lasted for weeks, emphasizing SGD's crucial role in nutrient transport under the influence of tropical cyclones.