• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.4
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• pp.413-433
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• 1994

Jinhae Bay once was a productive area of fisheries. It is, however, now notorious for its red tides; and oxygen deficient water-masses extensively develop at present in summer. Therefore the shellfish production of the bay has been decreasing and mass mortality often occurs. Under these circumstances, the three-dimensional numerical hydrodynamic and the material cycle models, which were developed by the Institute for Resources and Environment of Japan, were applied to analyze the processes affecting the oxygen depletion and also to evaluate the environment capacity for the reception of pollutant loads without dissolved oxygen depletion. In field surveys, oxygen deficient water-masses were formed with concentrations of below 2.0mg/l at the bottom layer in Masan Bay and the western part of Jinhae Bay during the summer. Current directions, computed by the $M_2$ constituent, were mainly toward the western part of Jinhae Bay during flood flows and in opposite directions during ebb flows. Tidal currents velocities during the ebb tide were stronger than that of the flood tide. The comparision between the simulated and observed tidal ellipses showed fairly good agreement. The residual currents, which were obtained by averaging the simulated tidal currents over 1 tidal cycle, showed the presence of counterclockwise eddies in the central part of Jinhae Bay. Density driven currents were generated southward at surface and northward at the bottom in Masan Bay and Jindong Bay, where the fresh water of rivers entered. The material cycle model was calibrated with the data surveyed in the field of the study area from June to July, 1992. The calibrated results are in fairly good agreement with measured values within relative error of $28\%$. The simulated dissolved oxygen distributions of bottom layer were relatively high with the concentration of $6.0{\sim}8.0mg/l$ at the boundaries, but an oxygen deficient water-masses were formed within the concentration of 2.0mg/l at the inner part of Masan Bay and the western part of Jinhae Bay. The results of sensitivity analyses showed that sediment oxygen demand(SOD) was one of the most important influence on the formation of oxygen depletion. Therefore, to control the oxygen deficient water-masses and to conserve the coastal environment, it is an effective method to reduce the SOD by improving the polluted sediment. As the results of simulations, in Masan Bay, oxygen deficient water-masses recovered to 5.0mg/l when the $50\%$ reduction in input COD loads from Masan basin and $70\%$ reduction in SOD was conducted. In the western part of Jinhae Bay, oxygen deficient water-masses recovered to 5.0mg/l when the $95\%$ reduction in SOD and $90\%$ reduction in culturing ground fecal loads was conducted.

• ALGAE
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• v.35 no.3
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• pp.263-275
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• 2020

Water temperature is known to affect the growth and feeding of marine dinoflagellates. Each dinoflagellate species grows well at a certain optimal temperature but dies at very cold and hot temperatures. Thus, changes in water temperatures driven by global warming and extremely high or low temperatures can affect the distribution of dinoflagellates. Yihiella yeosuensis is a mixotrophic dinoflagellate that can feed on only the cryptophyte Teleaulax amphioxeia and the chlorophyte Pyramimonas sp. Furthermore, it grows fast mixotrophically but rarely grows photosynthetically. We explored the direct and indirect effects of water temperature on the growth and ingestion rates of Y. yeosuensis feeding on T. amphioxeia and the growth rates of T. amphioxeia and Pyramimonas sp. under 7 different water temperatures (5-35℃). Both the autotrophic and mixotrophic growth rates of Y. yeosuensis on T. amphioxeia were significantly affected by temperature. Under the mixotrophic and autotrophic conditions, Y. yeosuensis survived at 10-25℃, but died at 5℃ and ≥30℃. The maximum mixotrophic growth rate of Y. yeosuensis on T. amphioxeia (1.16 d^-1) was achieved at 25℃, whereas the maximum autotrophic growth rate (0.16 d^-1) was achieved at 15℃. The maximum ingestion rate of Y. yeosuensis on T. amphioxeia (0.24 ng C predator^-1 d^-1) was achieved at 25℃. The cells of T. amphioxeia survived at 10-25℃, but died at 5 and ≥30℃. The cells of Pyramimonas sp. survived at 5-25℃, but died at 30℃. The maximum growth rate of T. amphioxeia (0.72 d^-1) and Pyramimonas sp. (0.75 d^-1) was achieved at 25℃. The abundance of Y. yeosuensis is expected to be high at 25℃, at which its two prey species have their highest growth rates, whereas Y. yeosuensis is expected to be rare or absent at 5℃ or ≥30℃ at which its two prey species do not survive or grow. Therefore, temperature can directly or indirectly affect the population dynamics and distribution of Y. yeosuensis.

• Korean Journal of Environmental Biology
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• v.22
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• pp.11-29
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• 2004

This study was conducted bimonthly from June 2001 to June 2003 to investigate the seasonal variation of the zooplankton community in Gwangyang Bay, Zooplankton were collected at 9 stations using a NORPAC net from surface layer. The zooplankton community consisted of 47 taxa and the mean abundance was 6,205 inds. $m^{-3}$ during the survey period. The maximum abundance was observed to be 20,060 inds. $m^{-3}$ in June 2002 and the minimum in August 2001 with 630 inds. $m^{-3}$. Copepods were the predominant constituent, wihich comprised 4.6~84.1% (mean 38.2%) of the total zooplankton abundance. Dominant species of copepods were Acartia omorii, Acartia erythraea, Centropages abdominalis, Paracalanus parvus. Paracalanus parvus dominated from June 2001 to December 2002. A red tide causative dinoflagellate, Noetiluca scintillans, dominated from June 2002 to February 2003, Acartia omorii and Centropages abdominalis dominated in winter and spring seasons. While, Acartia erythraea dominated in summer and fall seasons. In June and August, Cladocerans and Cirriped larvae dominated. The abundance of zooplankton according to the tidal cycle showed considerable fluctuations with a range of 2,768~15,856 inds. $m^{-3}$ $(\risingdotseq$ 5.7 times).

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.4
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• pp.341-348
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• 2016

Micro-algae, one of the biological resources for alternative energy, has been heavily studied. Among various methods to analyze the status of the micro-algae including counting, screening, and flocculation, the flocculation approach has been widely accepted in many critical applications such as red tide removal study or microalgae resource study. To characterize the flocculation status of the micro-alga. A traditional optical modality, i.e., photospectrometry, measuring the optical density of the flocs has been frequently employed. While this traditional optical method needs shorter time than the counting method in flocculation status analysis, it has relatively lower detection accuracy. To address this issue, a novel real-time micro-algae flocculation analysis method based on the lens-free shadow imaging technique (LSIT) is introduced. Both single cell detection and floc detection are simultaneously available with a proposed lens-free shadow image, confirmed by comparing the results with optical microscope images. And three shadow parameters, e.g., number of flocs, effective area of flocs, and maximum size of floc, enabling quantification of the flocculation phenomenon of micro-alga, are firstly demonstrated in this article. The efficacy of each shadow parameter is verified with the real-time flocculation monitoring experiments using custom developed cohesive agents.

• Journal of Satellite, Information and Communications
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• v.1 no.2
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• pp.1-7
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• 2006

GOCi (Geostationary Ocean Color Imager) is one of the COMS payloads that KARI is currently developing and scheduled to be in operation from around 2008. Its primary objective is to monitor the Korean coastal water environmental condition. We report the current progress in development of the integrated optical model as one of the key analysis tools for the GOCI in-orbit performance verification. The model includes the Sun as the emitting light source. The curved Earth surface section of 2500 km x 2500 km includingthe Korean peninsular os defined as a Lambertian scattering surface consisted of land and sea surface. From its geostationary orbit, the GOCI optical system observes the reflected light from the surfaces with varying reflectance representing the changes in its environmental conditions. The optical ray tracing technique was used to demonstrate the GOCI in-orbit performances such as red tide detection. The computational concept, simulation results and its implications to the on-going development of GOCI are presented.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.3
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• pp.113-123
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• 2008

We have analyzed a long term data of marine environments, red tide information and meteorology acquired by NFRDI and KMA, in order to understand the characteristics of marine environments in the Narodo coastal waters which is known to be the first outbreak region of Cochlodinium polykrikoides blooms. During the period of from 1992 to 2007, Cochlodinium polykrikoides blooms have first occurred more often in August. However, the outbreak time of the blooms tended to be earlier annually, and in addition, the surface salinity also had a tendency to increase. Consequently, it suggested that there might be a relationship between the transition of the outbreak time of the blooms and salinity. On the other hand, insolation was relatively rich but precipitation was relatively scarce in Gohung Province, compared to Yeosu or Tongyeong, when Cochlodinium polykrikoides blooms first occur in Narodo coastal waters. Average water temperature and salinity in August in Narodo coastal waters were all higher than those in Gamak and Jinhae bays, suggesting that Narodo coastal waters are a region of relatively high water temperature and high salinity. Also, concentrations of nutrients and chlorophyll- a were significantly low than those in Jinhae Bay, which is known to be a eutrophicated region, while the overall water quality seemed to be similar to Gamak Bay. The results of PCA(Principal Component Analysis) proved that insolation and water temperature are the most important factors for the outbreak of Cochlodinium polykrikoides blooms in Narodo coastal waters while concentrations of COD and dissolved oxygen are secondly important. Furthermore, typhoons also appeared to be one of most important factors for the outbreak of Cochlodinium polykrikoides blooms.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.3
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• pp.121-126
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• 1975

Chlorophyll a content in marine phytoplankton and nutrient in seawater were determined to study the influence of eutrophication of Jinhae Bay area on primary production. Sampels were taken in the surface layer and bottom of 21 stations in Jinhae Bay including Masan Bay and Hengam Bay, ana adjacent waters such as Geoje Bay and the estuary of Naktong River for refrence during summer Period in 1974. Chlorophyll a content was ranged from $0.52\;mg/m^3\;to\;25.16\;mg/m^3$ in whole area. Mean value of chlorophyll a was the highest in Masan Bay and the lowest in GeojeBay. It was noteworthy that chlorophyll a content of Hengam Bay was not much higher than that of neighboring ares and rather lower than that of the estuary of Naktong River in spite of high phosphate content. Linear relationship between increase of nutrients and chlorophyll a was found in Masan Bay and the estuary of Naktong River where N/P ratio of nutrients was over 12. This relationship however could not be found in most area of Jinhae Bay where N/P ratio of nutrients was lower than 2 which might due to the wastewater from the Chemical Fertilizer plant. Red tide and low dissolved oxygen waters due to eutrophication were observed during summer period in Masan Bay.

• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.97-104
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• 2006

Though stringent guidelines are in place to protect the harbor environment, pollution from ships, from the ports terminals. Discharge from the ballast tanks of ships, though illegal, does occur. Such vessels, arriving from distant ports of call, can introduce exotic species of plants and animals, causing disruption of the local food web. Discharges rich in nitrogen can generate the rapid growth of plankton, eventually leading to a condition known as red tide that is lethal to some coastal organisms. In addition to the harbor's negative effects on marine organisms, the diesel engines of the ships and the trucks that haul cargo to and from the ports release large volumes of diesel exhaust into the atmosphere. IMO(International Maritime Organization) is strongly proceeding with adoption of a new maritime environment convention and coming into effect for regulation enhancement about the pollutants which are happened in a ship recently. Study about the conventions that our country currently comes into effect, and there is during forwarding and correspondence must be performed effectively. In this paper, International convention on the control of harmful Anti-Fouling system on ship, Ballast water management, Prevention of air pollution from ships, treat a main pending problem in ocean related environmental regulation convention.

• Journal of Wetlands Research
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• v.19 no.4
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• pp.383-392
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• 2017

In 2013, August and September(early) as summer and October and November as Fall the probe of eutrophication has been done at 22 sampling points from the entrance of Danghang Bay (Jinhae Bay) to Geosan reservoir. In Danghang Bay, total chlorophyll(TChl) concentration of summer was 3.7 times higher than that of fall, and sampling points closer to the center showed 1.8 times higher concentrations than sampling points near the fringe where fresh water encountered. Eutrophication Index(EI) exceeded 1 at all sampling points in Danghang Bay during summer and fall, and if other conditions for algae growth met there was a possibility red tide to bloom at any place. There was a tendency of EI to gradually increase moving up from the entrance of bay to the inner side during summer and fall. Especially there was a sudden increase by 2.3 times higher at sampling points of 13~22 (planned region as Madong reservoir) than at other points during fall. Nitrogen was a limiting nutrient for growth of algae during summer and fall in Danghang Bay, but phosphorus was a limiting nutrient during summer rainy season. During summer and fall, multiple linear regression analysis between EI and COD, DIN, and DIP showed a significant positive relationship and that DIP was the most effective variable. Whereas multiple linear regression analysis between TChl and COD, DIN, DIP, and DSi showed a significant positive relationship and that DIP was also the most effective variable during summer. There was no significant correlation between TChl and the other parameters during fall.

• Journal of Environmental Science International
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• v.24 no.11
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• pp.1485-1491
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• 2015

There are two treatment processes that are currently applied to ships are the biological treatment process using the activated sludge and the electrochemical treatment. However, neither of them are able to remove both nitrogen and phosphorus due to their limited ability to remove organic matters, which are main causes of the red tide. This study was conducted to identify the characteristics of nitrogen removal factors from manure wastewater by replacing the final settling tank in SBR (Sequencing Batch Reactor) process and applying immersion type hollow fiber membrane. SBR process is known to have an advantage of the least land requirement in special environment such as in ship and the immersion type hollow fiber membrane is more stable in water quality change. As the result, the average in the cases of DO (Dissolved Oxygen) is 2.9(0. 6~3.9) mg/L which was determined to be the denitrifying microorganism activity in anaerobic conditions. The average in the cases of ORP (Oxidation Reduction Potential) is 98.4~237.3 mV which was determined to be the termination of nitrification since the inflection point was formed on the ORP curve due to decrease in the stirring treatment after the aeration, same as in the cases of DO. Little or no variation in the pH was determined to have positive effect on the nitrification. T-N (Total Nitrigen) removal efficiencies of the finally treated water were 71.4%, 72.3% and 66.5% in relatively average figures, thus was not a distinct prominence. In being applied in ships in the future, the operating conditions and structure improvements are deemed necessary since the MEPC (Marine Environment Protection Committee). 227(64) ship sewage nitrogen is less than the standard of 20 Qi/Qe mg/L or the removal rate of 70%.