Progress in in-situ observation of methane flux at sediment-water interface in cold seep

As the most critical interface, the seabed sediment-water interface has become the key target of carbon cycle research in cold seep in recent years. To obtain accurately the fluid flux at marine sediment-water interface, reconstruct objectively the interface environmental processes, and evaluate the environmental effects, a complete set of accurate, efficient, and scientific underwater in-situ measurement techniques of methane flux shall be developed. The significance and value of methane flux at sediment-water interface in cold seep are reviewed in the topics including working principle, methods, advantages and disadvantages of free bubble methane flux seep tent, acoustic reflection, timing imaging, in situ dissolved methane membrane methane sensor, and laser Raman spectral measurement methods. The investigated regions, research status, and progress in the field are presented. Finally, the future direction and trend of development in this field are expected in technical aspect, to provide a reference for the in situ observation of methane flux in marine cold seep.