Extraordinary slow degradation of dissolved organic carbon (DOC) in a cold marginal sea.
Dissolved organic carbon (DOC) is the largest organic carbon reservoir in the ocean, and the amount of carbon in this reservoir rivals that in atmospheric CO2. In general, DOC introduced into the deep ocean undergoes a significant degradation over a centennial time scale (i.e., ~50 μM to ~34 μM in the North Atlantic and Mediterranean Sea). However, we here show that high concentrations of DOC (58 ± 4 μM) are maintained almost constantly over 100 years in the entire deep East/Japan Sea (EJS). The degradation rate in this sea is estimated to be 0.04 μmol C kg(-1) yr(-1), which is 2-3 times lower than that in the North Atlantic and Mediterranean Sea. Since the source of DOC in the deep EJS is found to be of marine origin on the basis of δ(13)C-DOC signatures, this slow degradation rate seems to be due to low temperature (<1 °C) in the entire deep water column. This observational result suggests that the storage capacity of DOC in the world ocean is very sensitive to global warming and slowdown of global deep-water overturning.
School of Earth and Environmental Sciences/RIO, Seoul National University, Seoul, 151-747, Republic of Korea.|Department of Earth and Marine Sciences, Jeju National University, Jeju, 690-756, Republic of Korea.
Tae-Hoon
TH
Kim
School of Earth and Environmental Sciences/RIO, Seoul National University, Seoul, 151-747, Republic of Korea.
Guebuem
G
Kim
School of Earth and Environmental Sciences/RIO, Seoul National University, Seoul, 151-747, Republic of Korea.
Shin-Ah
SA
Lee
Research Group for Marine Geochemistry (ICBM-MPI Bridging Group), Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University, 26111 Oldenburg, Germany, and Max Plank Institute for Marine Microbiology (MPI), Bremen, Germany.
Thorsten
T
Dittmar