Key Laboratory of Marine Ecosystem and Biogeochemistry State Oceanic Administration Second Institute of Oceanography Ministry of Natural Resources Hangzhou 310012 China;
Key Laboratory of Marine Eco-environmental Science and Technology Marine Bioresource and Environment Research Center First Institute of Oceanography Ministry of Natural Resources Qingdao 266061 China;
Yap Trench; hadal zone; organic carbon loading; specifi csurface area; preservation capacity;