Marine dissolved organic carbon (DOC) is one of the largest carbon reservoirs on Earth and plays an important role in carbon sequestration and climate regulation. It has been speculated that the majority of marine DOC possesses intrinsic stability that allows the DOC pool to grow in size. To test this speculation, we conducted long-term bioassay experiments where natural deep-sea microbial communities were incubated with deep-sea DOC at varying concentrations (2 to 55 times) for one year. It was found that while the amount of DOC degraded by microbes increased with concentration factors, there was an upper limit on the extent of microbial utilization. We will discuss in this talk the potential mechanisms behind the limited degradation and its implications for understanding the storage potential of organic carbon sequestration in the ocean.
 

dissolved organic carbon,amino acids,biodegradation,organic carbon reservoir,organic carbon sequestration