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Lee J.S.,Ocean Observation & Information Section | Lee J.S.,Korean University of Science and Technology | Han J.H.,Korea Basic Science Institute | An S.-U.,Ocean Observation & Information Section | And 3 more authors.
Ocean Science Journal | Year: 2014

We characterized the biogeochemical organic carbon cycles in the surface sediment layer (< 25 cm) in the coastal waters of Namhae off the South Sea of Korea. The total and diffusive sediment oxygen uptake rates were measured using an in situ benthic lander equipped with a benthic chamber and a microprofiler. The bottom water above the sediment-water interface was incubated to estimate the benthic flux of the dissolved inorganic nutrients and the total alkalinity using an in situ benthic chamber. In addition, the particulate materials vertically deposited onto the surface sediment and the sedimentation rates were quantified to calculate the sedimentary organic carbon budget. The total oxygen uptake rate was in the range 34.9 to 54.1 mmol O2 m-2d-1, which is about three times the diffusive oxygen uptake rate. An abnormal oxygen peak observed in the anoxic sediment layer suggests a higher bioirrigation activity in the sediment layer. The oxidation rate of organic carbon at the sediment surface showed a very narrow range (36 ± 7 to 37 ± 7 mmol C m-2d-1), and the burial flux into the sediment layer was in the range 3 to 13 mmol C m-2d-1, which accounted for 9% to 36% of the remineralization rate of the organic carbon. The N and P requirement fluxes for pelagic production could be supported by 29% and 42% of the benthic flux, respectively, which strongly suggests a benthic-pelagic coupling in the coastal area of the South Sea of Korea. © 2014, Korea Ocean Research & Development Institute (KORDI) and the Korean Society of Oceanography (KSO) and Springer Science+Business Media Dordrecht. Source


Lee J.S.,Marine Chemistry & Geochemistry Research Center | Lee J.S.,Korean University of Science and Technology | An S.-U.,Hanyang University | Park Y.-G.,Korean University of Science and Technology | And 9 more authors.
Ocean Science Journal | Year: 2015

We have developed a new autonomous benthic lander for deep-sea research, the Korea Institute of Ocean Science and Technology (KIOST) BelcII and BelpII. The benthic lander was successfully tested at 950 and 1450 m water depths on the slope off the southwestern part of the Ulleung Basin in the East Sea of Korea. The ex situ measurements of the total oxygen uptake (TOU) rates at all the stations exceeded the in situ measurement values, and may indicate artificial effects from onboard incubation. The TOU rates were estimated to be 5.80 mmol m–2 d–1 and 3.77 mmol m–2 d–1 at water depths of 950 m and 1450 m, respectively. The benthic nutrient fluxes were also higher at water depths of 950 m, which indicates a partitioning of organic degradation with water depth. In addition, the negative phosphate and nitrogen benthic flux ratios and the higher nitrate removal flux via the sediment–water interface at the slope imply that the nitrogen in the bottom water may be preferentially removed via microbial respiration processes in the sediments, and may be coupled with the low nitrogen-to-phosphate ratio found in the deep water. Although our measurements comprised just two experiments in the slope sediment, the robust in situ measurement of the benthic fluxes in the slope sediment is a forerunner for new research into the biogeochemical cycles across the shelf edge–slope–basin system in the East Sea. © 2015, Korea Ocean Research & Development Institute (KORDI) and the Korean Society of Oceanography (KSO) and Springer Science+Business Media Dordrecht. Source

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