• Geosciences Journal
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• v.22 no.6
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• pp.989-1000
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• 2018

The provenance of the Central Yellow Sea Mud (CYSM) in the Yellow Sea has been attracted a great deal of attention over the last three decades, but a consensus is not yet reached. In this study, 101 surface sediment samples collected from the CYSM were investigated to determine provenance and transport mechanisms in the area using the clay minerals and major element components. The Huanghe sediments are characterized by higher smectite, but the Changjiang sediments are more abundant illite contents. Western Korean rivers contain more kaolinite and chlorite than do Chinese rivers. The Chinese rivers have higher $Fe_2O_3$, MgO, and CaO than the Korean rivers at the same $Al_2O_3$ concentration. Therefore, the clay minerals and major element concentrations can be useful indicator for the source. Based on our results, we suggest that the surface sediments in CYSM were composed mainly of Changjiang sediments, mixed a partly with sediments from the Huanghe and the western Korean rivers. Although the northwestern part of CYSM is proximate to the Huanghe, the contents of smectite and CaO were extremely low. It could be evidence that the Huanghe materials do not enter directly into the CYSM due to the Shandong Peninsula Front. Considering the oceanic circulation in the Yellow Sea, the Changjiang sediments could be transported eastward with the Changjiang Diluted Water and then mixed in CYSM via the Yellow Sea Warm Current (YSWC). Huanghe sediments could be provided by coastal currents (Shandong Coastal Current and Yellow Sea Coastal Current) and the YSWC. In addition, sediments from western Korean rivers might be supplied into the CYSM deposit via the Korean Coastal Current, Transversal Current, and YSWC.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1090-1098
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• 2005

Benzoyl peroxide is very toxic to aquatic organisms but environmental concentration or exposure effects were not studied. Distribution of the chemical among multimedia environment was estimated using EQC(Equilibrium Criterion) model based on the physical-chemical properties to evaluate the risk of benzoyl peroxide in environment. Level I describes a situation that 100,000 kg of benzoyl peroxide is emitted into the environment which is equilibrium and steady-state without degradation and advection condition. Level II describes a situation that a constant rate of 1,000kg/h of benzoyl peroxide is continuously discharged into the environment which is equilibrium and steady-state with degradation and advection condition. Level III describes a situation that 1,000 kg/h of benzoyl peroxide is continuously introduced in each air, water, soil, and sediment compartment which are non-equilibrium and steady-state with degradation, advection, and inter-media transfer condition. In Level I and II calculations the chemical was distributed to soil(68.3%) and water(28.7%). In Level III calculation it was primarily distributed to soil(99.9%) and overall residence time was estimated to be 3.4 years. Benzoyl peroxide can be persistent in environment.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.1
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• pp.31-41
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• 1997

This study was carried out to investigate the composition and the distribution of the benthic community in the coastal area of Inchon seasonally from May 1994 to February 1995, and to estimate the environmental factors that effect the temporal and the spatial changes of benthic species composition. In the present study, 231 species were collected with the average density of 455 ind./$m^2$. The dominant species were Heteromastus sp., Sternaspis scutata, Chaetozone setosa, Mediomastus sp., Glycinde sp., Glycera sp. and Nephtys oligobranchia, which are in the polychaete group; abundance of these species showed seasonal and spatial variations. The study area was divided into 4 regions by cluster analysis such as outside area of Palmido (I), main channel region and adjacent are of Shihwa sea wall (II), north-eastern area of Youngjongdo (III), and the Inchon harbor and the mouth area of Sorae harbor (IV). The particle size of sediment which generally influences the distribution of the benthic community, the differences of the concentration of heavy metals, and of the dissolved oxygen, the increase of the proportion of polychaetes and molluscs, the absence of the crustacean phoxocephalids, and the increase of the abundance of pollution indicator species, indicated that the environment of the areas have been degrading gradually from Group I to Group IV.

• Ocean and Polar Research
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• v.27 no.4
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• pp.359-379
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• 2005

In order to understand the spatial and temporal variations of nutrients and factors controlling their distribution in Gwangyang Bay, this study was carried out bimonthly from June 2001 to July 2003, Inorganic silicate and nitrate concentrations ranged from $0.04{\mu}M\;to\;69.5{\mu}M(avg.\;12.9{\mu}M)$, and from $0.12{\mu}M\;to\;42.2{\mu}M\;(avg.\;7.83{\mu}M)$, respectively. Silicate concentrations measured just after the typhoon were the highest with an average of $43.2{\mu}M$ at the surface layer in June 2001, whereas the highest nitrate concentration $(avg.\;37.0{\mu}M)$ was observed in the surface layer in July 2003. River runoff apparently influenced variations in silicate and nitrate concentrations (r=0.701 and 0.728, p<0.000, respectively) as well as salinity (r=-0.628, p<0.000). Phosphate concentrations ranged from $0.24{\mu}M\;to\;5.70{\mu}M\;(avg.\;1.34{\mu}M)$ and were highest at stations 5, 6, and 7, near a fertilizer plant with an average of $2.01{\mu}M$. On the basis of N/P and Si/N molar ratios, limiting nutrients have varied temporary and spatially. During 2001-2002, nitrogen was a limiting nutrient in the study area, and Phosphate was limited when a large volume of freshwater flowed into the bay. Silicate was limited when the high standing crops of phytoplankton occurred in the whole study area throughout 2003, and in the inner bay in February and August 2002. During the study period, factors controlling the distribution of nutrients might be summarized as follows; 1) inflow of freshwater by heavy rain accompanied by typhoons and frequent rainfall in summer, showing high concentrations of silicate and nitrate, 2) release of high phosphate concentrations from the fertilizer plant located in the south of Moydo to adjacent stations, 3) release of nutrients from bottom sediment, 4) magnitude of occurrence of phytoplankton standing crops.

• Journal of the Korean Society for Marine Environment & Energy
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• v.3 no.4
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• pp.56-64
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• 2000

Behavior of trace metals in Masan Bay, Korea was studied in August 1998 when the oxygen deficient condition occurred. Dissolved Cd and Zn concentration in the surface waters decreased with increasing distance from Masan Harbor. Dissolved concentrations of Cd, Cu Pb and Zn in the surface waters were higher than bottom waters. Particulate(acid-teachable fraction) concentrations of Cu, Cd and Pb in the surface waters of Masan Bay decreased with increasing distance from Masan Harbor. Bottom waters contained higher concentrations of particulate Cd, Cu, Pb and Zn than surface waters. Distribution coefficients between dissolved and particulate phase (K/sub d/) of Cu and Cd decreased with the increasing distance from the Harbor, possibly due to reaction of these elements with sewage-derived particulate matter Al, Zn, Cu, Cd, and Pb in the surface sediment showed relatively high concentration in the inner Masan Bay.

• 한국해양학회지
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• v.26 no.1
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• pp.24-37
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• 1991

Marine benthic diatoms and environmental factors were studied at 60 sites on the Mangyung-Dongjin tidal flat of the west coast of Korea. Sediment samples were taken quantitatively from the upper 5 mm layer to obtain a representative estimate of the epipelic and epipsammic cell concentration. Surface sediments taken simultaneously with the quantitative diatom samples were analysed for the grain size. Exposure duration of study sites were calculated by the tide data recorded at Kunsan Outer-Harbour. Coarse sediments dominated mainly on the offshore coastal and lower tidal flat, whereas fine sediments occurred on inner and higher tidal flat. Total 371 diatom taxa were collected and the genera represented by a great number were Navicula and Nizschia. The 16 abundant species occupying more than 1% of total cell number are of the following: Paralia sulcata, Navicula sp. 1, Navicula arenaria, Cymatosira belgica, Amplora holsatica, Amphora coffeaeformis, Achnanthes hauckiana, Rhaphoneis amphiceros, Thalassionema nitzschioides. Navicula sp. 2, Dimeregramma minor, Amphora sp. 1, Cyclotella atomus, C, striata, Nitzschia kuetzingiana, Stephanodiscus sp. 1. The distribution pattern of these dominant species are described in relation to the habitat condition. Most of these species showed high densities in fine sediments. However, they occurred even silty sand and sandy sediments in low abundance. The epipsammic forms belonging to the Araphidineae and Monoraphidineae were restricted on the lower tidal flat. The typical species found in coarse sediments were: Cocconeis sp. 1, Opephora martyi, Amphora sabyii, Dimeregramma minor var. nana, Fragilaria virescens var. oblongella, F. virescens, Cocconeis grata. The higher tidal flat consisting of fine sediments showed relatively higher cell numbers than the lower tidal flat. River mouth region was the highest in abundance.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.3
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• pp.251-261
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• 2003

As a part of an on-going project investigating flux of materials in Gomso Tidal Flat, we have monitored temporal and spatial distribution of nitrogen components(TN, PON, DON, DIN) and have sought the relationships with the freshwater input(tidal range, salinity), the biological activities(chlorophyll-${\alpha}$, TP, DIP, silicate) and the resuspended bottom sediment in seawater(SPM) from 1999 to 2000. TN in seawater was 39.05 $\mu\textrm{m}$ol 1$\^$-1/ (31.03∼42.93 $\mu\textrm{m}$ol 1$\^$-1/) without any statistical difference(p<0.05) between the studied periods. Organic nitrogen (DON and PON) occupied 75％, 95％, 73％, and 75％ in April, August, September and November, respectively. DON and PON have been found within the narrow concentration ranges of 11.30∼16.38 $\mu\textrm{m}$ol 1$\^$-1/ and 13.16∼20.04 $\mu\textrm{m}$ol 1$\^$-1/ in spite of severe environmental differences through the studied periods. Dissolved fractions of nitrogen(DON and DIN) occupied 53∼65％ of TN. Only DIN varied with an evident temporal variability: low concentrations(1.325∼1.616 $\mu\textrm{m}$ol 1$\^$-1/) in August and high enrichment(8.377∼14.65 $\mu\textrm{m}$ol 1$\^$-1/) in September. High consumption rate of DIN by phytoplankton and a long-lasted drought probably induced such low concentration of DIN in August. Eventually heavy precipitation probably introduced plenty of new nitrogen sources into Gomso Bay in September. The portion of PON, DON and DIN in the total nitrogen was 40％, 38％ and 22％, respectively. Their contents were in the order of DON>PON>DIN for the year round except PON>DON>DIN only in September. The highest DON portion in August probably due to the active microbial decomposition of organic material in summer. Only in April, some evident negative correlations have been found between chlorophyll-${\alpha}$ and DIN mostly nitrate(-0.64, p<0.01), phosphate(-0.46, p<0.01) and silicate(-0.55, p<0.01). The Si(OH)$_4$/DIN/DIP ratios in the water column suggests the limitation of DIN for the growth of phytoplankton during the dry summer in Gomso Bay, which was the case of August in this work. Even with some difference between the studied periods, the primary factors on the distribution of nitrogen components in seawater overlying the Gomso Tidal Flat have been the tidal range and the freshwater input, but the additional variations were due to the biological activities.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.9 no.2
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• pp.64-72
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• 2004

We measured the vertical profiles of $O_2$, H$_2$S, and pH in sediment pore water beneath marine cage fish farms using a microsensor with a 25 ${\mu}{\textrm}{m}$ sensor tip size. The sediments are characterized by high organic material load. The oxygen consumption, hydrogen sulfide oxidation, and sulfate reduction rates in the microzonations (derived from the vertical distribution of chemical species concentration) were estimated by adapting a simple one-dimensional diffusion-reaction model. The oxygen penetration depth was 0.75 mm. The oxic microzonations were divided into upper and lower layers. Due to hydrogen sulfide oxidation within the oxic zone, the oxygen consumption rate was higher in the lower layer. The total oxygen consumption rate integrated with reaction zone depth was estimated to be 0.092 $\mu$mol $O_2$cm$^{-2}$ hr$^{-1}$ . The total hydrogen sulfide oxidation rate occurring within 0.7 mm thickness was estimated to be 0.030 $\mu$mo1 H$_2$S cm$^{-2}$ hr$^{-1}$ , and its turnover time in the oxic sediment layer was estimated to be about 2 minutes. This suggests that hydrogen sulfide was oxidized by both chemical and microbial processes in this zone. The molar consumption ratio, calculated to be 0.84, indicates that either other electron accepters exit on hydrogen sulfide oxidation, or elemental sulfur precipitation occurs near the $O_2$- H$_2$S interface. Total sulfate reduction flux was estimated to be 0.029 $\mu$mol cm$^{-2}$ hr$^{-1}$ , which accounted for more than 60% of total $O_2$ consumption flux. This result implied that the degradation of organic matter in the anoxic layer was larger than in the oxic layer.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.4
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• pp.392-400
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• 2003

We used an oxygen microelectrode to measure the vertical profiles of oxygen concentration in sediments located near point sources of organic matter. The measurements were carried out between 13th and 17th May, 2003, in semi-closed bay and coastal sediments in the central part of the South Sea. The measured oxygen penetration depths were extremely shallow and ranged from 1.30 to 3.80 mm. This suggested that the oxidation and reduction reactions in the early diagenesis should be studied at the mm depth scale. In order to estimate the oxygen consumption rate, we applied the one-dimension diffusion-reaction model to vertical profiles of oxygen near the sediment/water interface. Oxygen consumption rates were estimated to be between 10.8 and 27.6 mmol O$_2$ m$\^$-2/ day$\^$-1/(average: 19.1 mmol O$_2$ m$\^$-2/ day$\^$-1/). These rates showed a positive correlation with the organic carbon of the sediments. The corresponding benthic organic carbon oxidation rates calculated using an modified Redfield ratio (170/110) at the sediment/water interface were in the range of 89.5-228.1 mg C m$\^$-2/ day$\^$-1/(average: 158.0 mg C m$\^$-2/ day$\^$-1/). We suggest that these results are maximum values at the presents situation in the bay because the sampling sites were located near point sources of organic materials. This study will need to be carried out at many coastal sites and throughout the seasons to allow an understanding of the mechanisms of eutrophication e.g. the spatial distribution of oxygen consumption within the oxic zone and hypoxic conditions in the coastal sea.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.23 no.2
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• pp.91-108
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• 2018

An ecological study on subtidal macrobenthic fauna was conducted from 25 stations in the estuarine area of Wando-Doam Bay, southern coast of Korea during August 2013. A total of 186 species was collected with a mean density of $1,229ind./m^2$ and a mean biomass of $265.7g/m^2$. Polychaetes showed the richest benthic fauna comprising 43% of total fauna, whereas mollusks appeared as density- and biomass-dominant fauna accounted for 45% and 48% of the mean density and biomass, respectively. The number of species and mean faunal density were relatively higher at the stations surrounded by Sinjido, Joyakdo and Gogeumdo showing a gradual decrease toward inner bay stations. Species number and density were negatively correlated with bottom water temperature, but they were positively correlated with both the bottom salinity and DO. The most dominant species in terms of density was a semelid bivalve, Theora fragilis which showed a positive correlation with TOC content of surface sediment and its high density occurred around Gogeum-Sinji-Joyakdo area where dense aquaculture facilities exist. In the bay mouth area, an amphipod species, Eriopisella sechellensis showed its higher density at the stations with low organic content but fine grains. The combination of water temperature, salinity, pH of bottom water, water and sulfur content of the surface sediment could explain 71% of the spatial distribution of macrobenthic fauna from the Bio-Env analysis. From the cluster analysis, the study area consisted of 6 distinct station groups lineated from offshore area toward inner area. Ampharete arctica, Goniada maculata, Eriopisella sechellensis, Theora fragilis, Caprella sp. were identified as the main contributing faunas in classification by the SIMPER analysis. From the value of BPI, the benthic communities at the inner and central Wando-Doam Bay were assessed to be in a normal condition whereas those at the outer Wando harbor and Gogeum-Sinji-Joyakdo area were assessed in a poor or very poor condition due to the high concentration of particulate organic matter might be originated from the nearby dense aquaculture facilities. This study indicated that pristine inner bay has been influenced by the organic material supplied from the outer bay. Thus it is necessary to establish an ecological management plan to reduce organic enrichment of sediment from dense aquaculture facilities in the outer bay.