• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.2
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• pp.45-58
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• 2012

For the development of reference values and evaluation of water quality in various environmental conditions, we divided the coastal region around Korean peninsular into 5 distinctive ecological regions based on the influence of surface current, depth, tidal range, turbidity, and climate condition. We used national marine environment monitoring data collected by National Fisheries Research & Development Institute(NFRDI) from 2000-2009. For the reference values, we used maximum seasonal mean from 2000 to 2007 for DIN, DIP, and chlorophyll-a and minimum seasonal mean for secchi depth measured at stations without the influence of river runoff in each ecological regions. For the reference value of bottom dissolved oxygen saturation, we used minimum mean value of 90% calculated from minimal riverine influence stations of whole regions. We calculated enrichment score for each assessment criteria. The enrichment score of DIN, DIP, and Chlorophyll-a was 1 (=< reference value), 2 (< 110% of reference value), 3 (< 125% of reference value), 4 (< 150% of reference value), and 5 (> 150% of reference value). The enrichment score of DO saturation and Secchi depth was 1 (> reference value), 2 (> 90% of reference value), 3 (>75 % of reference value), 4 (> 50% of reference value), and 5 (< 50% of reference value). We calculated water quality index using weighted linear combination of five enrichment score for the comparison of whole regions. From the water quality index distribution calculated from all stations between 2000 and 2007 period, we classified into 5 grade based on the standard deviation calculated from total water quality index. We assigned grade very good(I), good(II), moderate(III), bad(IV), and very bad(V) when the water quality index was less than 23, minimum + 1 sd, +2 sd, +3 sd, and grater than minium+ 3 sd, respectively.

• The Korean Journal of Malacology
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• v.30 no.2
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• pp.117-126
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• 2014

To assess the effect of environmental factors on the sustainability of cultured production manila clam (Ruditapes philippinarum), we investigated the habitat characteristics of tidal flat (Hwangdo and Jeongsanpo in Taean). We measured the physiochemical parameters (temperature, salanity, pH, dissolved oxygen and nutrients) and the characteristics (mean size, chemical oxygen demand, ignition loss, C/N ratio and C/S ratio) of surface sediments. The C/N ratio of Hwangdo and Jeongsanpo were 9.0, 5.3 and the C/S ratio was 0.162, 0.159. The concentration of chlorophyll a at Hwangdo was higher than that of Jeongsanpo and species of micro algae were 102 and 100. The enrichment factor (Ef) and index of accumulation rate (Igeo) of the metals showed that those research areas can be classified as heavily polluted, heavily to moderately polluted, or more or less unpolluted, respectively. So two survey area of cultured clams in the tidal flat have been effected by the various environmental conditions, there are needed an improvement methods and continuous research for increasing the production of manila clam (Ruditapes philippinarum).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.348-354
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• 2001

This study was conducted to estimation of change characteristics for water quality by the dyke gate operation in the Keum River estuary. The estimation data made use of surveyed data in Keum River estuary by NERDI (National Fisheries Research and Development Institute) during $1990\~1999$. Shown to compare water quality changes at st. A and st. D in Figure 1, the concentrations of TSS, COD and nutrients at st. A were as high as about $2\~4$ times than those at st. D due to affection of fresh water discharge in the Keum River. The percentages of water quality change at surface water by dyke gate operation in the Keum River estuary were shown that TSS (Total Suspended Solid) was decrease to $56\%,\;47\%$ at st. A and D, and COD (Chemical Oxygen Demand) was increase to $68\%,\;71\%$ at st. A and D, respectively. The changes percentage of DIN (Dissolved Inorganic Nitrogen) by dyke gate operation in the Keum River estuary were increase high to $95\%$ at surface water and $7\sim30\%$ at bottom water, but those of DIP (Dissolved Inorganic Phosphorus) were increase to $2.8\sim8.6\%$ at surface water and $28\%$ at bottom water. The range of fluctuation for water quality at each station by dyke gate operation has shown that salinity and TSS are little better than before dyke gate operation, but COD show highly fluctuation. Also we studied estimation of characteristics of water quality change by the season, COD was increased except the summer, TSS was decreased to all season. DIN was increased to about $61\sim172.1\%$ for all season, but DIP was increased to the spring and decreased to the autumn, DIN enrichment in the estuary by dyke gate operation are interpreted to improvement of organic matter decomposition and nitrification by increasing the residence time and to increase nutrient flux in sediments due to decreasing dissolved oxygen and increasing a deposit matter.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.2
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• pp.106-117
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• 2006

We measured the concentrations of organic matter and metallic elements (Al, Fe, Cr, Mn, Ni, Cu, Zn, As, Cd, Pb and Hg) in the surface sediments of Masan Harbor (in the southern sea, Korea) to evaluate the geochemical characters of sediment and the pollutions by organic matter and metallic elements. The mean grain size of the surface sediments in the study area ranged from $5.6{\phi}$ to $7.8{\phi}$, indicating silt sediment. The water content of the surface sediments exceeded 60% except at some stations. The contents of ignition loss (IL), total organic carbon (TOC) and total nitrogen (TN) ranged from 7.2-14.3%, 1.2-3.2%, and 0.10-0.28%, respectively. Based on the C/N ratios, the organic matter in the surface sediments of Masan Harbor may originate from terrigenous sources including fluvial inputs (mainly sewage in urban areas). The chemical oxygen demand (COD) and acid volatile sulfide (AVS) ranged from $11.3-29.9\;mgO_2/g\;dry$ and 0.20-4.47 mgS/g dry, respectively, and low concentrations were observed near a shipping route. In addition, the concentrations of metallic elements showed large spatial variations in Masan Harbor and the distributions of metallic elements were also comparable to those of organic matter. This implies that the distributions of organic matter and metallic elements in the surface sediments of Masan Harbor are mainly controlled by biogenic matter and artificial action (mainly dredging). In addition, we calculated the enrichment facto. (EF) and geoaccumulation index (Igeo) in order to evaluate pollution by metallic elements. The enrichment of metallic elements relative to Al was three to eighteen times higher at the study sites, compared to levels in the Earth's crust except for Fe, Ni and Mn. In addition, the Igeo class indicated that the surface sediments in the study area were moderately to strongly polluted in terms of metallic elements.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.4
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• pp.297-302
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• 2004

A chitinase-producing bacterium was isolated from seashore mud around Beobseongpo in Chunmam province through the use of a selective enrichment culture. The best chitinase producing strain was isolated and identified as Serratia marcescens KY from its characteristics. For effective production of chitinase, optimum pH, temperature, and agitation speed were investigated in flask cultures. The optimum pH using Serratia marcescens KY was between pH 6 and 7 and the chitinase produced was 37.9 unit/mL. On the other hand, the optimal pH of the Serratia marcescens ATCC 27117 was 7.5, and the produced amount of chitinase was 35.2 unit/mL. The optimal temperature for chitinase production for Serratia marcescens KY and Serratia marcescens ATCC 27117 was $30^{\circ}$. The cell growth pattern at different temperature was almost identical to the chitinase production. To investigate the optimal shaking speed under optimal culture, speeds were varied in the range of 0∼300 rpm. The maximum production of chitinase was carried at 200 rpm although the cell growth was the highest at 150 rpm. It indicates that oxygen adjustment is required for the maximum chitinase production. Using optimal conditions, batch cultures for comparing Serratia marcescens KY and Serratia marcescens ATCC 27117 were carried out in a 5 L fermentor. The oxygen consumption was increased with the increase of culture. Especially, at 120 h of culture Serratia marcescens KY and Serratia marcescens ATCC 27117 produced 38.3 unit/mL, and 33.5 unit/mL, respectively.

• Journal of Ecology and Environment
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• v.35 no.4
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• pp.279-289
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• 2012

This study conducted a comparative analysis of benthic macroinvertebrate communities in the Fosu and Benya lagoons in Ghana, based on the anthropogenic effect on the two lagoons. Salinity, oxygen, temperature, conductivity, turbidity and pH were measured, invertebrate richness and species densities were determined. The AZTI Marine Biotic Index (AMBI) and multivariate statistics were used to determine the different responses of fauna to pollution. The fauna were categorized into five ecological groups based on the degree of tolerance of the different species to pollution: disturbance-sensitive species; disturbance-indifferent species, disturbance-tolerant species, second-order opportunistic species; and first-order opportunistic species. The Fosu Lagoon supported more pollution tolerant species, whereas the Benya Lagoon had more species that were sensitive to organic enrichment under relatively unpolluted conditions. Chironomus sp., which is adapted to virtually anoxic conditions, was the most abundant in the Fosu Lagoon whereas Nemertea sp. was the most abundant in the Benya Lagoon. The numerical and relative abundance (%) of all 7 taxa in the Fosu Lagoon was 1,359 and 92.35%, respectively. The numerical and relative abundance (%) of all 34 taxa in the Benya Lagoon was 2,459 and 87.52%, respectively. Expectedly, the level of dissolved oxygen in the less saline Fosu Lagoon was higher than that in the more saline Benya Lagoon. The reduced photoperiod and photosynthetic activities of aquatic plants might account for this trend. There is a need to implement comprehensive monitoring and management initiatives for sustaining the ecological health of coastal lagoons in Ghana in order to support the many people that depend upon these ecosystems for their livelihood.

• Journal of Microbiology and Biotechnology
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• v.15 no.5
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• pp.992-1000
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• 2005

Campylobacter is one of the emerging foodborne pathogens, and its worldwide incidence rate is extremely high. This study was undertaken to isolate and identify Campylobacter strains from chicken carcasses in the local markets, and analyze their characteristics regarding oxygen tolerance. They were isolated after aerobic enrichment and identified by biochemical, physiological, and morphological characteristics, PCR, and 16S rDNA sequencing. Their oxygen tolerances were analyzed in terms of the cell surface hydrophobicity, cell fatty acid composition, and oxidoreductase. Five strains of C. jejuni were isolated and identified from 61 isolates from 50 chickens. Among them, C. jejuni IC21 grew well in Brucella broth and commercial milk under aerobic condition. However, in the aerobic exposure, the cell surface hydrophobicity of C. jejuni IC21 was almost the same as the other isolates, even though its morphology changed from the spiral-bacilli form into the coccoid form. Fatty acid analyses showed that all Campylobacter strains had a high composition of $C_{19:1}$, cyclopropane fatty acid, and that the amount of the other fatty acids were very similar between them. Interestingly, however, only oxidoreductase activities of C. jejuni IC21 increased highly under aerobic exposure even though its activities were almost the same as the other C. jejuni strains just after microaerobic culture. It had 11.8 times higher catalase activity, 4.4 times higher for SOD, and 2.0 times higher for NADH oxidase activities. Therefore, in the case of the aero-adaptive C. jejuni IC21, expression of oxidoreductase significantly increased under oxidative stressed condition, which might allow it to survive for a longer time and grow on food under aerobic exposure. Such new strain might be one of the explanations for the increase of campylobacteriosis.

• Korean Journal of Ecology and Environment
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• v.42 no.4
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• pp.422-431
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• 2009

This study was to provide basic data for aquatic ecosystem research using fishes. Field sampling was carried out at five selected sites of Gap Stream, and fish samples, especially for a selection of sentinel species were collected three times in June, September, and October 2007. We analyzed total length distribution of Zacco platypus in relation with the season and the sampling sites, and then compared with total body weight, condition factor (K), and age distribution of the fish. The fish population data were compared with physico-chemical water quality, obtained from the Ministry of Environment, Korea. Water quality analysis showed a significant nutrient enrichment, based on total nitrogen (TN) and total phosphorus (TP), and organic matter pollution, based on biological oxygen demand (BOD) and chemical oxygen demand (COD) in the Site 5, which is directly influenced by wastewater disposal plant (WDP). Population analysis of the sentinel species showed that the total number of individuals, age distribution, and the population size-structure were influenced by the effluents from the WDP, and that reproductive failure of young-age population were evident in Site 5. According to the relation analysis of total weight to K, the disturbed population was mainly attributed to combined effects of habitat modifications and chemical degradations. Regression analysis of K values against water quality parameters showed significant (p<0.05) positive relations with nutrient and organic matter contents. Our data suggest that the population structure using a sentinel fish species reflected the ambient water quality in the stream and that diagnosis of aquatic ecosystem health using Z. platypus population may be practical for water resource and ecosystem conservations.

• Korean Journal of Materials Research
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• v.31 no.1
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• pp.38-42
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• 2021

In this study, high temperature wetting analysis and AZ80/Ti interfacial structure observation are performed for the mixture of AZ80 and Ti, and the effect of Al on wetting in Mg alloy is examined. Both molten AZ80 and pure Mg have excellent wettability because the wet angle between molten droplets and the Ti substrate is about 10° from initial contact. Wetting angle decreases with time, and wetting phenomenon continues between droplets and substrate; the change in wetting angle does not show a significant difference when comparing AZ80-Ti and Mg-Ti. As a result of XRD of the lower surface of the AZ80-Ti sample, in addition to the Ti peak of the substrate, the peak of TiAl3, which is a Ti-Al intermetallic compound, is confirmed, and TiAl3 is generated in the Al enrichment region of the Ti substrate surface. EDS analysis is performed on the droplet tip portion of the sample section in which pure Mg droplets are dropped on the Ti substrate. Concentration of oxygen by the natural oxide film is not confirmed on the Ti surface, but oxygen is distributed at the tip of the droplet on the Mg side. Molten AZ80 and Ti-based compound phases are produced by thickening of Al in the vicinity of Ti after wetting is completed, and Al in the Mg alloy does not affect the wetting. The driving force of wetting progression is a thermite reaction that occurs between Mg and TiO2, and then Al in AZ80 thickens on the Ti substrate interface to form an intermetallic compound.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.9 no.1
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• pp.30-39
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• 2004

In order to understand the environmental impact of marine cage fish farms, we measured the vertical fluxes of particulate to the sediment, the distribution of organic carbon in core samples, sediment oxygen consumption rate (SOD), and macrobenthos with increasing distance from a fish cage in Miruk island located in Tongyong. The experiment was performed in August 2003. Measured values gradually decreased with distance, indicating that the organic matter in the sediment derived from the fish farm. The dominant macrobenthos species were Tharyx mulifilis, Lumbrineris longifolia, Sigambra tentaculata, and Capitella capitata, occupying 88% of the total population. Capirella capirata, an opportunistic polychaete species, were especially abundant between 0 to 5 m radius range. The estimated impact regions of organic matter enrichment based on sediment consilmption rates and compositions of macrobenthos were in good agreement. Most organic matter derived from the fish farm was deposited within a 10 m radius and then dispersed horizontally to nearby (at least 50 m) surface sediment. The vertical organic carbon fluxes to the sediment at the fish farm were higher by a factor of two than those outside the area. The remineralization organic carbon in the upper sediment layer was estimated to be 50% (1.07 g C m$^{-2}$ day$^{-1}$ ) at the fish farm. In contrast, outside the area, 30% (0.30 g C m$^{-2}$ day$^{-1}$ ) of organic carbon was recycled and the remaining 70% was deposited to the deep sediment layer.