Typhoon stimulates the production of nitrous oxide of water column and sediment in coastal bays

Under the influence of global climate change, both frequency and intensity of typhoons are increasing. This study examines the impact of the typhoon on nitrous oxide (N2O) dynamics in coastal bays, which are considered the most active areas of N2O production in the ocean. Employing the 15N stable isotope labeling technique, coupled with the stable isotope mass spectrometry and analysis of key biogeochemical parameters, we conducted a series of five continuous cruises before and after typhoons in Zhanjiang Bay, a semi-closed coastal bay in the northern South China Sea. Our results showed that the typhoon initially led to a sharp decrease in N2O concentration in Zhanjiang bay. However, the typhoon also triggered a substantial production of N2O in both water column and sedimentary environments, therefore facilitating a rapid recovery of N2O levels within a short time period. In the water column, typhoon-induced enhancement of in-situ N2O production may be attributed to a substantial input of nutrients and terrestrial particles, which provide substrates and create anaerobic or hypoxic microenvironments favorable for N2O production. Concurrently, in the sediment, the deposition of phytoplankton-derived particles following typhoon-induced blooms introduces substantial fresh particulate organic matter, further facilitating N2O production. Our findings suggest that typhoons represent an efficient, yet transient, nitrogen removal mechanism that has previously been underestimated. By elucidating aspects of the nitrogen cycle in bays, this research aids in shaping policies aimed at mitigating greenhouse gas emissions triggered by typhoons.