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Extraordinary slow degradation of dissolved organic carbon (DOC) in a cold marginal sea.

Kim TH, Kim G, Lee SA, Dittmar T - Sci Rep (2015)

Bottom Line: 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).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.

View Article: PubMed Central - PubMed

Affiliation: School of Earth and Environmental Sciences/RIO, Seoul National University, Seoul, 151-747, Republic of Korea.

ABSTRACT
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.

No MeSH data available.


Vertical profiles of dissolved organic carbon (DOC), potential temperature, and δ13C-DOC.(a–c) Vertical profiles of (a) DOC, (b) potential temperature, and (c) δ13C-DOC in the East/Japan Sea (open circle), North Pacific (black lines), North Atlantic (black dotted lines), and Mediterranean Sea (gray dotted lines). Data in the North Pacific, North Atlantic, and Mediterranean Sea are from Hawaii Ocean Time-series (HOT), Bermuda Atlantic Time-series (BATS), and Santinelli et al. (ref. 26), respectively. Samples for δ13C-DOC in the East/Japan Sea were collected in station 10 (42 °N). The depth profiles of δ13C-DOC in the major oceans are from the North Central Pacific (31 °N) and the Sargasso Sea (31 °N).
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f2: Vertical profiles of dissolved organic carbon (DOC), potential temperature, and δ13C-DOC.(a–c) Vertical profiles of (a) DOC, (b) potential temperature, and (c) δ13C-DOC in the East/Japan Sea (open circle), North Pacific (black lines), North Atlantic (black dotted lines), and Mediterranean Sea (gray dotted lines). Data in the North Pacific, North Atlantic, and Mediterranean Sea are from Hawaii Ocean Time-series (HOT), Bermuda Atlantic Time-series (BATS), and Santinelli et al. (ref. 26), respectively. Samples for δ13C-DOC in the East/Japan Sea were collected in station 10 (42 °N). The depth profiles of δ13C-DOC in the major oceans are from the North Central Pacific (31 °N) and the Sargasso Sea (31 °N).

Mentions: Vertical profiles of DOC concentration were determined on several cruises covering the main EJS during the course of three years (Fig. 1). The average DOC concentrations in the surface layer (0–200 m) and in the deep (>200 m) layer over the entire area of the EJS were 68 ± 6 and 58 ± 4 μM, respectively (Fig. 2). In general, the DOC concentrations in the surface layer of EJS were comparable to those in the major world oceans (60–80 μM)141516. However, the DOC concentrations in the deep layer of the EJS are significantly higher than those in the major oceans (34–43 μM)61718 (Fig. 2) and slightly higher than or similar to those in the Arctic Ocean (54 ± 3 μM, up to ~4000 m)19 and the Nordic seas (50 μM, up to ~3500 m)20, where deep water formation occurs. In the Greenland Sea, one of the Nordic seas, the concentrations of DOC decrease from the surface (60 μM) to the deep layer (53 μM, <1500 m depth) and reach a constant DOC concentration (50 μM) in the deeper layer (>1500 m depth)20. Therefore, the concentration of DOC in the deep bottom water of the EJS seems to be the highest reported so far in the world oceans.


Extraordinary slow degradation of dissolved organic carbon (DOC) in a cold marginal sea.

Kim TH, Kim G, Lee SA, Dittmar T - Sci Rep (2015)

Vertical profiles of dissolved organic carbon (DOC), potential temperature, and δ13C-DOC.(a–c) Vertical profiles of (a) DOC, (b) potential temperature, and (c) δ13C-DOC in the East/Japan Sea (open circle), North Pacific (black lines), North Atlantic (black dotted lines), and Mediterranean Sea (gray dotted lines). Data in the North Pacific, North Atlantic, and Mediterranean Sea are from Hawaii Ocean Time-series (HOT), Bermuda Atlantic Time-series (BATS), and Santinelli et al. (ref. 26), respectively. Samples for δ13C-DOC in the East/Japan Sea were collected in station 10 (42 °N). The depth profiles of δ13C-DOC in the major oceans are from the North Central Pacific (31 °N) and the Sargasso Sea (31 °N).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4561884&req=5

f2: Vertical profiles of dissolved organic carbon (DOC), potential temperature, and δ13C-DOC.(a–c) Vertical profiles of (a) DOC, (b) potential temperature, and (c) δ13C-DOC in the East/Japan Sea (open circle), North Pacific (black lines), North Atlantic (black dotted lines), and Mediterranean Sea (gray dotted lines). Data in the North Pacific, North Atlantic, and Mediterranean Sea are from Hawaii Ocean Time-series (HOT), Bermuda Atlantic Time-series (BATS), and Santinelli et al. (ref. 26), respectively. Samples for δ13C-DOC in the East/Japan Sea were collected in station 10 (42 °N). The depth profiles of δ13C-DOC in the major oceans are from the North Central Pacific (31 °N) and the Sargasso Sea (31 °N).
Mentions: Vertical profiles of DOC concentration were determined on several cruises covering the main EJS during the course of three years (Fig. 1). The average DOC concentrations in the surface layer (0–200 m) and in the deep (>200 m) layer over the entire area of the EJS were 68 ± 6 and 58 ± 4 μM, respectively (Fig. 2). In general, the DOC concentrations in the surface layer of EJS were comparable to those in the major world oceans (60–80 μM)141516. However, the DOC concentrations in the deep layer of the EJS are significantly higher than those in the major oceans (34–43 μM)61718 (Fig. 2) and slightly higher than or similar to those in the Arctic Ocean (54 ± 3 μM, up to ~4000 m)19 and the Nordic seas (50 μM, up to ~3500 m)20, where deep water formation occurs. In the Greenland Sea, one of the Nordic seas, the concentrations of DOC decrease from the surface (60 μM) to the deep layer (53 μM, <1500 m depth) and reach a constant DOC concentration (50 μM) in the deeper layer (>1500 m depth)20. Therefore, the concentration of DOC in the deep bottom water of the EJS seems to be the highest reported so far in the world oceans.

Bottom Line: 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).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.

View Article: PubMed Central - PubMed

Affiliation: School of Earth and Environmental Sciences/RIO, Seoul National University, Seoul, 151-747, Republic of Korea.

ABSTRACT
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.

No MeSH data available.