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Distinguished Lecture

Distinguished Lecture - BG

Minhan DAI
Xiamen University

Wed- 31 Jul, 12:00-12:30pm
MR 300, Level 3

"On the Interactive Eutrophication, Hypoxia and Ocean Acidification in the Coastal Ocean"

Many studies have shown that coastal hypoxia is primarily associated with autochthonous organic carbon (Auto-OC) production, stimulated by coastal eutrophication resulting from excessive terrestrial nutrient runoff. Nutrients stimulate algal blooms in coastal surface waters. Sinking and remineralization of algal biomass drive dissolved oxygen (DO) consumption below the pycnocline. Therefore, Auto-OC is believed to be the predominant oxygen sink. Other studies, however, have suggested that Auto-OC may support only a fraction of DO consumption in the hypoxic zone. The relative contributions from eutrophication-induced autochthonous and terrestrially sourced allochthonous organic matter in causing coastal hypoxia are, however, still the subject of considerable debate despite decades of research. Another emerging but less studied environmental problem associated with entrophication is the enhanced ocean acidification (OA) in the coastal ocean, which often occurs accompanied by hypoxia. This enhanced acidification is typically induced by two processes. One is the in situ decomposition of the settled organic matter, which produces CO2 and decreases pH. The other is the decrease of the buffering capacity of the water, which further decrease pH.

This study examines major drivers of hypoxia and OA in both the East China Sea off the Changjiang estuary and in South China Sea off the Pearl River estuary. Also examined is the interplays between eutrophication, hypoxia, and ocean acidification in these two highly impacted systems. My presentation will then examine the global scale environmental issues related to eutrophication and its interactive biogeochemistry with hypoxia and ocean acidification in the coastal system. My research also highlights that both the hydrodynamic and biogeochemistry should be taken into consideration and multidisciplinary research approach is essential in order to diagnose individual processes in complex coastal environment.

Minhan Dai is a Chair Professor of Marine Biogeochemistry at Xiamen University, China ( where he serves as the Director of the State Key Laboratory of Marine Environmental Science. Minhan Dai’s research interests include ocean biogeochemistry of carbon and nutrients and geochemistry of radioactive elements in surface and ground waters.

Born in 1965 and raised in Hangzhou, Minhan Dai earned his B.S. degree from Xiamen University and his Ph.D. from Université Pierre & Marie Curie, France in 1995. After a Doherty Foundation Postdoctoral Fellowship at Woods Hole Oceanographic Institution (WHOI), he took a faculty position at Xiamen University in 1998. He was elected as an Academician of the Chinese Academy of Sciences in 2017.

Minhan Dai has published over 150 papers in leading international journals ( He is a leading PI of a “973” project funded through National Basic Research Program of China on “Carbon cycling in China Seas - budget, controls and ocean acidification” (CHOICE-C) which is at her second phase funded through 2019. He has served on many national and international committees.