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Aragonite Undersaturation in Gwangyang Bay, South Korea: Effects of Fresh Water Input
Kim, Dongseon,Yang, Eun-Jin,Baek, Seung Ho,Kim, Kyung-Hee,Jeong, Jin-Hyun,Kim, Young-Ok 한국해양학회 2014 Ocean science journal Vol.49 No.3
Dissolved inorganic carbon (DIC) and alkalinity were precisely measured for surface and bottom waters in Gwangyang Bay, Korea, during the four seasons to assess seasonal variations of aragonite saturation state (${\Omega}_{arag}$). Both the surface and bottom waters were undersaturated with respect to aragonite during summer but were supersaturated during the other seasons. The summertime undersaturation of the surface waters with respect to aragonite may have been a result of the dilution effect caused by higher seasonal river runoff. In the bottom waters, the average DIC concentration increased by $40.6{\mu}mol\;kg^{-1}$ from spring to summer, while the average alkalinity decreased by $74.7{\mu}eq\;kg^{-1}$. As a result, the alkalinity/DIC ratio decreased from 1.07 in spring to 1.01 in summer and pH also decreased from 7.91 to 7.48, which resulted in the summertime undersaturation of the bottom waters.
Kim, Dongseon,Choi, Sang Hwa,Kim, Kyung Hee,Shim, JeongHee,Yoo, Sinjae,Kim, Chul Ho Elsevier 2009 Continental shelf research Vol.29 No.11
<P><B>Abstract</B></P><P>Nutrients, chlorophyll-<I>a</I> (Chl<I>-a</I>), and environmental conditions were extensively investigated in the northern East China Sea (ECS) near Cheju Island during five research cruises from 2003 to 2007. In the eastern part of the study area, surface waters were characterized only by the Tsushima Current Water (TCW) during all five cruises. However, the western surface waters changed with season and were characterized by the Yellow Sea Cold Water (YSCW) in spring, the Changjiang Diluted Water (CDW) in summer, and the Yellow Sea Mixed Water (YSMW) in autumn. In spring and autumn, relatively high concentrations of nitrate and phosphate were observed in the surface waters in the western part of the study area, where vertical mixing brought large supplies of nutrients from deep waters. Changes in wind direction occasionally varied the inflow of the Changjiang plume in summer, clearly causing the annual variation in surface nitrate and phosphate concentrations in summer. In summer, the surface distribution of nitrate and phosphate did not coincide with that of silicate in the study area, which probably resulted from the significant drop in the Si:N ratio in the Changjiang plume since construction of the Three Gorges Dam (TGD). Despite large temporal and spatial variations in surface Chl-<I>a</I> concentrations, depth-integrated Chl-<I>a</I> concentrations exhibited little variation temporally and spatially. In the study area, surface Chl-<I>a</I> concentration did not well reflect the standing stocks of phytoplankton. The vertical distribution of Chl-<I>a</I> showed large temporal and spatial variations, and the main factor controlling the vertical distribution of Chl-<I>a</I> in summer was the availability of nitrate. The thermohaline front may play an important role for accumulation of phytoplankton biomass in spring and autumn.</P>
Water Quality Assessment at Jinhae Bay and Gwangyang Bay, South Korea
Kim, Dongseon,Baek, Seung Ho,Yoon, Dong-Young,Kim, Kyung-Hee,Jeong, Jin-Hyun,Jang, Pung-Guk,Kim, Young-Ok 한국해양학회 2014 Ocean science journal Vol.49 No.3
A new water quality index for evaluating the water quality of Jinhae Bay and Gwangyang Bay was developed. Four water quality parameters were selected as water quality indicators for the water quality index: dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), chlorophyll-a (Chl-a), and dissolved oxygen (DO). Reference levels of DIN, DIP, and Chl-a were determined as $6.22{\mu}mol\;L^{-1}$, $0.38{\mu}mol\;L^{-1}$, and $2.32{\mu}mol\;L^{-1}$, respectively, on the basis of a long-term dataset that was collected monthly in the Korea Strait over a period of seven years (2006-2012). The water quality index established for Jinhae Bay and Gwangyang Bay is (bottom DO grade ${\times}0.33$) + (surface Chl-a grade ${\times}0.33$) + (surface DIN grade ${\times}0.17$) + (surface DIP grade ${\times}0.17$). On the basis of a three-year observation, the water quality of Jinhae Bay was classified as "good" in winter and spring, "poor" in summer, and "fair" in autumn and exhibited large spatial variation, with the lowest-quality water observed in Masan Bay. The water quality of Gwangyang Bay was classified as "good" in winter, "fair" in spring, "poor" in summer, and "fair" in autumn. Unlike Jinhae Bay, the water quality of Gwangyang Bay exhibited minimal spatial variation. In both bays, water quality among the four seasons was worse during summer. It is essential that a survey for water quality evaluation be conducted during summer.
Evaluation of in vivo biodistribution using fluorescent probe labeled microplastic
Dongseon Kim,Hee-Kyung Kim,Dongkyu Kim,Tae-Jun Kwon,Chang-Hoon Shin,Kyungrim Yi,Jong-Wook Lee,Young-Eun Lee,Kil-Soo Kim 한국실험동물학회 2021 한국실험동물학회 학술발표대회 논문집 Vol.2021 No.7
Recent studies have shown that microplastics contaminate our food chain and accumulate in the intestines, liver, kidney, muscles, and more. Among them, polyethylene (PE) accounts for a large proportion of microplastics found in domestic fish and shellfish. It is necessary to study for the organs where the plastics were accumulated, and whether it affects the organism by inducing various responses such as oxidative stress. Therefore, form a part of this purpose, the study is performed to observe and evaluate the microplastic accumulation in organs by in vivo fluorescence imaging. We investigated the biodistribution analysis of microplastic particles by using PEs to classify two particle sizes (5μm, 50μm). For fluorescence imaging, PEs were labeled with cyanine5.5 carboxylic acid (Cy5.5), a near-infrared fluorescent dye. The labeled PEs were characterized by DLS, TGA/DSC, and in vitro IVIS spectrum CT (Perkin elmer, USA). To in vivo biodistribution imaging, each of labeled PEs was administered to ICR mice (n=5) as tracking markers, and the images were obtained by using IVIS spectrum CT (excitation 675 nm/emission 720 nm) at each time points. Mean fluorescence intensity graphs were analyzed by region of interests (ROI) that showed the Cy5.5 labeled PEs were gradually released through the stomach over 24 h after administration. In addition to in vivo imaging and ex vivo imaging were also performed after 24 h imaging, and the fluorescence of each organs were observed. However, there was no difference in organ distribution or secretion depending on the size of microplastics and the sex of mice. In this study, the in vivo biodistribution of the Cy5.5 labeled PEs were realized by fluorescent imaging using signal intensity profiles. In future studies, various microplastics and fluorescent probes would be utilized for comparison purpose.
Park, Geun-Ha,Lee, Seon-Eun,Kim, Young-il,Kim, Dongseon,Lee, Kitack,Kang, Jeongwon,Kim, Yeo-Hun,Kim, Haryun,Park, Seunghee,Kim, Tae-Wook Elsevier 2019 Science of the Total Environment Vol.681 No.-
<P><B>Abstract</B></P> <P>The atmospheric deposition of anthropogenic nitrogen is an increasingly important new source of nitrogen to the ocean. Coastal areas east of the Korean Peninsula are suitable for the investigation of the effects of atmospheric anthropogenic nitrogen on the ocean nutrient system because of the low riverine discharge rates and the prevailing influence of the East Asian outflow. Thus, we measured the concentrations of nitrate (NO<SUB>3</SUB> <SUP>−</SUP>) and ammonium (NH<SUB>4</SUB> <SUP>+</SUP>) in airborne particles and in precipitation from March 2014 to February 2016 at a coastal site (37.08°N, 129.41°E) on the east coast of Korea. The dry deposition of NO<SUB>3</SUB> <SUP>−</SUP> (27–30 mmol N m<SUP>−2</SUP> yr<SUP>−1</SUP>) was far greater than that of NH<SUB>4</SUB> <SUP>+</SUP> (6–8 mmol N m<SUP>−2</SUP> yr<SUP>−1</SUP>). The greater rate of dry NO<SUB>3</SUB> <SUP>−</SUP> deposition was associated with air masses traveling over northeastern China and central Korea. In contrast, the rates of wet deposition of NO<SUB>3</SUB> <SUP>−</SUP> (17–24 mmol N m<SUP>−2</SUP> yr<SUP>−1</SUP>) and NH<SUB>4</SUB> <SUP>+</SUP> (14–27 mmol N m<SUP>−2</SUP> yr<SUP>−1</SUP>) were comparable and were probably associated with in-cloud scavenging of these ions. The results indicate that the total deposition of NO<SUB>3</SUB> <SUP>−</SUP> and NH<SUB>4</SUB> <SUP>+</SUP> combined could contribute to ~2.4% and ~1.9% of the primary production in the coastal areas east of the Korean Peninsula and in the East Asian marginal seas, respectively, which would be a lower bound because the dry deposition of reactive nitrogen gas was not included. Our study shows that the atmospheric input of anthropogenic NO<SUB>3</SUB> <SUP>−</SUP> and NH<SUB>4</SUB> <SUP>+</SUP> may substantially increase phytoplankton biomass in the coastal waters of the East Sea near the Korean Peninsula.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Atmospheric Nitrogen Deposition (AND) was 64–89 mmol N m<SUP>−2</SUP> yr<SUP>−1</SUP> in the East Sea. </LI> <LI> AND was enhanced in air masses traveling over northeastern China and central Korea. </LI> <LI> AND could contribute to ~1.9% of the primary production of East Asian seas. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Kim, Dongseon,Park, Geun-Ha,Baek, Seung Ho,Choi, Yujeong,Kim, Tae-Wook Elsevier 2018 MARINE POLLUTION BULLETIN Vol.129 No.1
<P><B>Abstract</B></P> <P>We investigated the aragonite saturation state (Ω<SUB>arag</SUB>) during all four seasons in a coastal region of southern Korea that receives considerable freshwater input. The surface Ω<SUB>arag</SUB> values were higher during productive seasons with enhanced freshwater influences, likely due to an increased net removal of dissolved inorganic carbon (DIC) from the water column (i.e., biological control). In addition, during the productive seasons, enhancement of Ω<SUB>arag</SUB> was observed with decreasing salinity within a linear mixing zone present between river-influenced surface and saltier bottom waters. DIC appeared to be effectively sequestered from the warmer, less salty surface water by downward flux of organic matter, but not significantly affected by the relatively DIC-rich, cooler and saltier bottom waters under strong stratification conditions during these seasons (i.e., physical control). Low phytoplankton productivity and seasonal breakdown of the stratification caused reduced saturation in other seasons and made the study area a weak sink for atmospheric CO<SUB>2</SUB>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We investigated Ω<SUB>arag</SUB> in a coastal area that receives considerable freshwater input. </LI> <LI> The surface Ω<SUB>arag</SUB> values were higher during seasons with enhanced riverine impacts. </LI> <LI> It was due to enhancements in biological productivity and water column stability. </LI> </UL> </P>