• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.1
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• pp.38-46
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• 2012

This study carried out current status, characteristics, and problems of coastal environment management on semi-enclosed Masan Bay in Korea and suggests cost-effective and eco-friendly water quality management policy. The pollutants from terrestrial sources into the Bay have apparently environmental pollution problems, such as eutrophication, red tide, and hypoxia. The carrying capacity of the Bay is estimated by hydrodynamic model and ecosystem model, material circulation including bivalve in ecosystem is analyzed by the growth model of bivalve. The resulting reduction in the input load was found to be 50~90%, which is unrealistic. When the efficiency of water quality improvement through bivalve farming was assessed based on the autochthonous COD, 30.7% of the total COD was allochthonous COD and 69.3% was autochthonous COD. The overall autochthonous COD reduction rate by bivalve aquaculture farm was found to be about 6.7%. This study indicate that bivalve farming is about 31% less expensive than advanced treatment facilities that remove both nitrogen and phosphorous.

• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.308-321
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• 2013

In order to understand the population dynamics of red tide dinoflagellate Noctiluca scintillans, we examined its hydrographical and bio-ecological characteristics at 19 to 20 stations of Gwangyang Bay during all four seasons from 2010 to 2012. During the 3-year period, N. scintillans was seasonally abundant during summer with water temperatures ranging from $15^{\circ}C$ to $22^{\circ}C$ and salinity ranging from 25 psu to 30 psu. On the other hand, N. scintillans population density significantly decreased in spring, fall and winter, although they were present even in lower temperatures (< $4^{\circ}C$). However, high water temperature (> $27^{\circ}C$) and low salinity (< 12 psu) led to the disappearance of N. scintillans population. Chl-a concentration in winter, spring and fall was positively correlated with N. scintillans population density, whereas the N. scintillans population was negatively correlated with Chl-a concentration in summer. This implies that densities of prey population such as diatoms are one of important contributing factor for maintaining abundance of N. scintillans in winter, spring and fall and for increasing abundance of N. scintillans in summer. During summer season, bio-accumulation of N. scintillans population by the wind from southwest is also considered to be a key factor in triggering the formation of large-scale blooms in Gwangyang Bay.

• Journal of the Korean Society of Marine Environment & Safety
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• v.12 no.2 s.25
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• pp.75-79
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• 2006

In order to study the characteristics of water quality in coastal water and mechanism of phytoplankton blooms, factors of water quality were investigated in diatom bloom area due to rainfall event and no diatom bloom area Diatom blooms occurred after heavy rain and the dominant species were Skeletonema costatum($1,200{\sim}5,000cells/mL$) and Thalassiosira spp.($750{\sim}1,200cells/mL$). In diatom bloom area, water temperature, pH, and dissolved oxygen were observed at higher level than in no diatom bloom area Although these two areas were only 20 meters apart from each other, sharp difference in coastal water quality between two areas was observed. In diatom bloom area, concentrations of nitrogen, phosphorus, and silicate were observed at lower level than in no diatom blooms area. This seems to be due to inflow of much trace metal such as Fe, Mo, Se and so on than nitrogen, phosphorus, and silicate by rainfall events. However, distinct differences in DIN/DIP and $DIN/SiO_2-Si$ between these two areas were not observed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.2
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• pp.308-323
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• 2021

In this study, we aimed to evaluate the environmental changes in Jinhae Bay caused by cooling water using numerical modeling. Cooling water discharge volume from the results of Case 1 (10 m³ sec^-1) showed that the environmental changes in Jinhae Bay were extremely insignificant throughout the study period. In the simulation conditions of Case 2 (100 m³ sec^-1), there was a decrease in water temperature of approximately 1 - 3℃ within a 5 km radius from the discharge outlet. In Case 3 (1000 m³ sec^-1), a decrease in water temperature of up to 4 - 5℃ was observed within a radius of 8 km from the discharge outlet and cooling water discharge spread throughout the Bay. Growth rate of microalgae decreased by up to 15 % in November, whereas it increased by up to 6 % near the Hangam Bay in Case 3. From the above results, we confirmed that the environmental changes in Jinhae Bay due to cooling water discharged from Tongyeong LNG station are extremely insignificant. Moreover, it is expected that cooling water discharge could be utilized as a counter measure for 'red tide bloom' or 'macroalgae growth'.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.1
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• pp.16-24
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• 2010

Utilization of dissolved organic phosphorus (DOP) and alkaline phosphatase (APase) activity by Skeletonema costatum, Chaetoceros didymus, Alexandrium tamarense and Heterosigma akashiwo under the phosphorus deficient condition were examined in the laboratory. S. costatum, C. didymus, A. tamarense and H. akashiwo could make use of phosphomonoester and nucleotide compounds for the growth of them as a phosphorus source. APase activity of S. costatum, C. didymus, A. tamarense and H. akashiwo began to be activated at dissolved inorganic phosphorus (DIP) concentrations less than $0.30\;{\mu}M$, $0.33\;{\mu}M$, $2.04\;{\mu}M$ and $0.63\;{\mu}M$ respectively, and their maximum APase activity were $0.01\;pmol\;cell^{-1}\;hr^{-1}$, $0.11\;pmol\;cell^{-1}\;hr^{-1}$, $1.63\;pmol\;cell^{-1}\;hr^{-1}$ and $0.19\;pmol\;cell^{-1}\;hr^{-1}$, respectively. Although each phytoplankton species displayed different APase activity for DOP utilization, their maximum APase activities were higher than maximum phosphorus uptake rates, inferring that these species might be able to keep growing under DIP-limited conditions thought utilizing effectively the hydrolized product of DOP. This result also implies that utilization of DOP might contribute to not only the growth of red tide forming phytoplankton but also the interspecific competition among phytoplankton species in coastal environments.

• Korean Journal of Environmental Agriculture
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• v.22 no.1
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• pp.16-25
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• 2003

Manun Reservoir, located in Andong district has the capacity of 2 million tons in irrigation water supply with the drainage area of $23.8\;km^2$. Manun Reservoir is over fifty year old, and shallow in depth. The ratio of drainage area (DA) to reservoir surface area (SA) as an effective physical parameter on water quality was 56.1 and was higher than those of other agricultural reservoirs. The ratio of reservoir storage (ST) to SA in Manun Reservoir was 4.79, and the mean depth was below 8m. Both ratios of DS/SA, total area (TA)/ST and ST/SA in Manun Reservoir were relatively higher than those in other agricultural reservoir and natural lakes in Korea. These physical parameters in Manun Reservoir, however, had a eutropic potential significance. Average of COD, IN, and TP in Manun Reservoir were 11.1 mg/L 1.426 mg/L, 0.093 mg/L, respectively. In the inflow stream of Manun Reservoir, the TN ($1.426{\sim}3.809\;mg/L$) was higher than those in reservoir. Only Lyngbya spp. was dominant in phytoplankton for this study period and Gymnodinium spp., Peridinium spp., and Cryptomonas spp. were dominant in zooplankton. According to the Carlson's trophic status index, Mnnun Reservoir was eutrophic in 1996, 1997, and 1999, and hypertrophic in 1998.

• Journal of Environmental Science International
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• v.14 no.2
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• pp.177-184
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• 2005

This study was to determine the fluctuation in phytoplankton assemblages with regarding to environmental conditions and nutrients, which were surveyed around Mokpo waters in the southwestern waters, Korea. Sampling was carried out on the Mokpo, Sinan, and Wando coasts from March to November 2003. The maximum sea surface temperature was recorded in August, and it ranged around $25^{\circ}C$ regardless of sampling sites. However, salinity in Mokpo waters showed a great variation, which ranged from 5-30 psu and recoded the minimum of 5 psu in July and the maximum of 30 psu in November. Moreover, in Mokpo waters, the chlorophyll a and SS concentration of the surface layer were also the highest values of $20\;{\mu}g\;l^{-1}\;and\;40\;{\mu}g\;l^{-1}$, respectively than those of Sinan and Wando waters. The concentrations of $NH_4-N,\;NO_2-N,\;NO_3-N,\;and\;PO_4-P$ were also he highest values of $0.018\;{\mu}mol\;^l{-1},\;0.062\;{\mu}mol\;l^{-1},\;1.2\;{\mu}mol\;l^{-1}\;and\;0.078\;{\mu}mol\;l^{-1}$, respectively in Morpo waters than those of Sinan and Wando waters. During the period of this study, the majority of the taxa were diatoms; Thalassiosira rotula, Rhizosolenia setigera, Prorocentrum minimum, Chaetoceros curvisetus, Leptocylindrus danicus, Pseudonitzschia pungens, and Chaetoceros spp. were detected in the dominant species of phytoplankton. The dinoflagellates were relatively abundant during the summer season in Wando waters, which attained an abundance of $10-20\%$. In Mokpo waters, DIN/DIP was the highest value of 700 in March, whereas the lowest was shown in Wando waters. However, DIN/DIP value in summer at Wando waters was extremely reversed, which appeared to be associated with the development of dinoflagellates. On the bais of factor analysis using SYSAT 6.0, nutrient showed somewhat correlation with chlorophyll a. Consequently, the process of discharge of fresh water in Mokpo waters plays an important role in extremely fluctuation in nutrients and conditions. Although Wando waters maintains a lack of nutrients, it should be influenced by different water current and may be associated with a concentration of nutrients.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.2
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• pp.83-99
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• 2005

To evaluate environmental charateristics of the South Sea and East China Sea on summer, water and sediment quality were measured in June 2001-2003. Surface layer was affceted by Warm water originated from the high temperature and salinity-Tsushima Warm Current, on the other hand, Yellow Sea Cold Water was spread to the bottom layer in the south-western part of the Jeju island, and salinity at stations near the Yangtze River was decreased below 29psu because of a enormous freshwater discharges. Thermocline-depth was formed at about 10m, and chlorophyll maximum layer was existed in and below the thermocline. COD(Chemical Oxygen Demand), TN(Total Nitrogen), and TP(Total Phosphorus) concentrations showed seawater quality grade II in surface layer of the most area, but concentrations of such as COD, Chl. a, TSS(Total Suspended Solid), and nutrients were greatly increased in the effect area of Yangtze River discharges. Correlations between dissolved inorganic nitrogen, Chl. a and salinity were negative patterns strongly, in contrast, those of inorganic phosphorus, COD and Chl. a were positive, which indicates that phytoplankton biomass and phosphorus are considered as important factors of organic matter distribution and algal growth, respectively. in the study area. The distribution of ignition loss, COD, and $H_2S$ of surface sediment were in the ranges of 2.61-8.81%, $0.64-11.86mgO_2/g-dry$, and ND-0.25 mgS/g-dry, respectively, with relatively high concentration in the eastern part of the study area. Therefore, to effective and sustainable use and management of this area, continuous monitoring and countermeasures about major input sources to the water and sediment, and prediction according to the environmental variation, are necessary.

• Korean Journal of Ecology and Environment
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• v.34 no.1 s.93
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• pp.20-29
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• 2001

The amount, chemical composition and optical property of extracellular dissolved organic carbon (EOC) by phytoplankton were examined using axenic cultures of Microcystis aeruginosa, Anabaena flos-aquae, and Oscillatoria agardhii. The extracellular organic matter was categorized into five fractions (hydrophobic acids; AHSs, hydrophobic neutrals; HoNs, hydrophilic acids; HiAs, hydrophilic bases; HiBs, and hydrophilic neutrals; HiNs) using three adsorbent resins(XAD-8, cation, and anion). The release pattern and chemical composition of EOC varied with algal species and their growth phases. Percentage of extracellular release increased with age in all cultures. HiAs were the dominant component of EOC in all cultures, whereas the proportion of HiAs decreased with age in all cultures. In contrast, the proportions of HiBs and HiNs increased as cultures aged. In particular, the HiN fraction increased from 0% to 44% of EOC in M. aeruginosa and from 3.0% to 28% in A. flos-aquae, respectively. The proportion of AHSs was higher in the cultures of A. flos-aquae(7.5${\sim}$16%) and O. agardhii (8.7${\sim}$16%) than M. aeruginosa(0.2${\sim}$2.5%). The proportions of AHSs increased with culture age in M. aeruginosa and O. agardhii, but decreased in A. flos-aquae. The specific UV absorbance also varied among species; 1.9 Abs${\cdot}$cm$^{-1}$/mgC${\cdot}$L$^{-1}$ for M. aeruginosa, 3.7 Abs${\cdot}$cm$^{-1}$/mgC${\cdot}$L$^{-1}$ for A. flos-aquae, and 13.0 Abs${\cdot}$cm$^{-1}$/mgC${\cdot}$L^{-1}$ for O. agardhii. The results of this study indicates that DOC excreted by three blue-green algae differed with species and the growth phase.