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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.


A map showing sampling stations for vertical dissolved organic carbon (DOC) profiles in the East/Japan Sea.Seawater samples for DOC analysis were collected with a Niskin sampler from 30 stations in the southern area and from 15 stations in the northern area of the EJS. The hydrological and biogeochemical surveys were conducted during four periods: May 8 to 22, 2007, on board the R/V M.A. Gagarinsky of the Pacific Oceanological Institute (POI), Russia; May 28 to June 2, 2007, onboard the R/V Tam-Yang of the Pukyung National University (PKNU), Korea; August 4 to 14, 2008, onboard the R/V HaeYang 2000 of the National Oceanographic Research Institute (NORI), Korea; and July 9 to 18, 2009, on board the R/V M.A. Lavrentyev of the POI, Russia. Map was created using Adobe Illustrator.
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f1: A map showing sampling stations for vertical dissolved organic carbon (DOC) profiles in the East/Japan Sea.Seawater samples for DOC analysis were collected with a Niskin sampler from 30 stations in the southern area and from 15 stations in the northern area of the EJS. The hydrological and biogeochemical surveys were conducted during four periods: May 8 to 22, 2007, on board the R/V M.A. Gagarinsky of the Pacific Oceanological Institute (POI), Russia; May 28 to June 2, 2007, onboard the R/V Tam-Yang of the Pukyung National University (PKNU), Korea; August 4 to 14, 2008, onboard the R/V HaeYang 2000 of the National Oceanographic Research Institute (NORI), Korea; and July 9 to 18, 2009, on board the R/V M.A. Lavrentyev of the POI, Russia. Map was created using Adobe Illustrator.

Mentions: The EJS is a semi-enclosed marginal sea and is divided into three major basins (Japan Basin, Ulleung Basin, and Yamato Basin), all of which are deeper than 2000 m (Fig. 1). The deep water masses (at depths greater than 1000 m) in the EJS are formed by deep convection or brine rejection in the Japan Basin891011. Using salinity and oxygen isotope budgets9, the rate of potential bottom-water formation due to brine rejection (at depths greater than 2500 m) was estimated to be approximately 4 × 1012 m3 yr−1. This brine rejection accounts for 25–35% of the subsurface water formed in the EJS. The turnover time of the EJS deep water mass was determined to be ~100 years by using radionuclides such as 14C and 226Ra1213 by assuming steady-state conditions.


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

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

A map showing sampling stations for vertical dissolved organic carbon (DOC) profiles in the East/Japan Sea.Seawater samples for DOC analysis were collected with a Niskin sampler from 30 stations in the southern area and from 15 stations in the northern area of the EJS. The hydrological and biogeochemical surveys were conducted during four periods: May 8 to 22, 2007, on board the R/V M.A. Gagarinsky of the Pacific Oceanological Institute (POI), Russia; May 28 to June 2, 2007, onboard the R/V Tam-Yang of the Pukyung National University (PKNU), Korea; August 4 to 14, 2008, onboard the R/V HaeYang 2000 of the National Oceanographic Research Institute (NORI), Korea; and July 9 to 18, 2009, on board the R/V M.A. Lavrentyev of the POI, Russia. Map was created using Adobe Illustrator.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: A map showing sampling stations for vertical dissolved organic carbon (DOC) profiles in the East/Japan Sea.Seawater samples for DOC analysis were collected with a Niskin sampler from 30 stations in the southern area and from 15 stations in the northern area of the EJS. The hydrological and biogeochemical surveys were conducted during four periods: May 8 to 22, 2007, on board the R/V M.A. Gagarinsky of the Pacific Oceanological Institute (POI), Russia; May 28 to June 2, 2007, onboard the R/V Tam-Yang of the Pukyung National University (PKNU), Korea; August 4 to 14, 2008, onboard the R/V HaeYang 2000 of the National Oceanographic Research Institute (NORI), Korea; and July 9 to 18, 2009, on board the R/V M.A. Lavrentyev of the POI, Russia. Map was created using Adobe Illustrator.
Mentions: The EJS is a semi-enclosed marginal sea and is divided into three major basins (Japan Basin, Ulleung Basin, and Yamato Basin), all of which are deeper than 2000 m (Fig. 1). The deep water masses (at depths greater than 1000 m) in the EJS are formed by deep convection or brine rejection in the Japan Basin891011. Using salinity and oxygen isotope budgets9, the rate of potential bottom-water formation due to brine rejection (at depths greater than 2500 m) was estimated to be approximately 4 × 1012 m3 yr−1. This brine rejection accounts for 25–35% of the subsurface water formed in the EJS. The turnover time of the EJS deep water mass was determined to be ~100 years by using radionuclides such as 14C and 226Ra1213 by assuming steady-state conditions.

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.