• Title/Summary/Keyword: Surface Waters

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Variations and Characters of Water Quality during Flood and Dry Seasons in the Eastern Coast of South Sea, Korea (한국 남해 동부 연안 해역에서 홍수기와 갈수기 동안 수질환경 특성과 변동)

  • Jeong, Do Hyeon;Shin, Hyeon Ho;Jung, Seung Won;Lim, Dhong Il
    • Korean Journal of Environmental Biology
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    • v.31 no.1
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    • pp.19-36
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    • 2013
  • Physiochemical characters of sea waters during summer flood- and winter dry-seasons and their spatial variations were investigated along the coastal area off the eastern South Sea, Korea. Using the hierarchical clustering method, in this study, we present comprehensive analyses of coastal waters masses and their seasonal variations. The results revealed that the coastal water of the study area was classified into six water masses (A to F). During summer season, the surface water was mainly occupied by the coastal pseudo-estuarine water (water mass B) with low salinity and high nutrients and the river-dominated coastal water (water mass C) with low nutrients, respectively. The bottom water was dominated by cold water (water mass D) with very low temperature, high salinity and high nutrients, compared to masses of surface water. Notably, the water mass B, with high concentrations of nutrients (silicate and nitrogen) and low salinity, which is strongly controlled by the water quality of river freshwater, seems to play an important role in controlling the water quality and further regulating physical processes on ecosystem in the eastern coastal area of South Sea. The water mass D (bottom cold water) coupled with a strong thermocline, which exists in near-bottom layer along the western margin of Korea Strait, has a low temperature, pH and DO, but abundant nutrients. This water mass disappears in winter owing to strong vertical mixing, and subsequently may act as a pool for nutrients during winter dry-season. On the other hand, vertically well-mixed water column during the winter season was typically occupied by the Tsushima (water mass E) and the coastal water (water mass F) with a development of coastal front formed in a transition zone between them. These winter water masses were characterized by low nutrient concentration and balance in N/P ratio, compared with summer season with high nutrient concentrations and strong N-limitation. Accordingly, the analysis of water masses will help one to better chemical and biological processes in coastal area. In most of the study area, characteristically, the growth of phytoplankton community is limited by nitrogen, which is clearly different with coastal environment of West Sea of Korea, with a relative lack of phosphorus. It showed the western and the southern coasts in Korea are substantially different from each other in environmental and ecological characteristics.

The Ecosystem of the Southern Coastal Waters of the East Sea, Korea I. Phytoplankton Community Structure and Primary Productivity in September, 1994 (한국 동해 남부 연안생태계 연구 1. 1994년 9월에 있어서의 식물플랑크톤의 군집구조와 1차생산력)

  • LEE Joon-Baek;HAN Myung-Soo;YANG HanR-Seob
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.31 no.1
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    • pp.45-55
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    • 1998
  • Phytoplankton community and primary productivity have been investigated in a fall season in the southern coastal waters of the last Sea, Korea. A strong thermocline formed at the 20\~60\;m$ layer and a cold water mass also existed in the bottom around Yong-il Bay. The offshore of the surveyed area was likely to be influenced by relatively warmer water, whereas the inshore represented Higher primary productivity with lower water temperature and lower salinity. A total of 133 species of phytoplankton occurred, representing 107 spp. of diatom, 23 spp. of dinoflagellate 3 spp. of silicoflagellate. Skeletonema costatum and Asterionellepsis glacialis were most predominant with more than $30\%$ dominance ratio, while Leptocylindrus danicus was also dominant at all transect lines. Standing crops of phytoplankton ranged from $2.7{\times}10^3\;to\;141.6{\times}10^3\;cell^{\ell-1}$. Chlorophyll a concentration varied with stations and layers, but the $30\~50$ m layer showed maximun with about $1.18{\mu}g{\ell}^{-1}$ rather than at the surface layer. It is believed that the maximun in standing crops and chlorophyll of phytoplankton formed at the $20\~50$ m layer above the thermocline during the survey. Phytoplankton primary productivity ranged from 0.32 to 3.04 mgC $m^{-3}\;hr^{-1}$, showing higher at the inshore than at the offshore. The range of integrated primary productivity was $263.3\~1085.5 mgC\;m^{-2}\;day^{-1}$ for the euphotic layer. Photosysthesis rates varied with the range from 0.76 to 8.04 mgC mgChl $\alpha^{-1}\;hr^{-1}$. Phytoplankton photosynthesis at the inshore was saturated at lower irradiance ($15\~35\%$ of surface) and showed higher efficiency, Thus, it revealed that the phytoplankton community probably adapted to the middle of euphotic layer because the depth of mixing layer became thinner due to the formation of thermocline.

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Vertical Profiles of Marine Environments and Micro-phytoplankton Community in the Continental Slope Area of the East China Sea in Early Summer 2009 (이른 여름 동중국해 대륙사면의 해양환경과 소형 식물플랑크톤 군집의 연직분포 특성)

  • Yoon, Yang Ho
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.16 no.3
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    • pp.151-162
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    • 2013
  • Studies of the distribution of micro-phytoplankton community and chlorophyll a concentration have focused on the vertical profiles of marine environmental factors such as water temperature, salinity, sigma-t, light intensity, and dissolved oxygen in the continental slope on the east parts of East China Sea in the early summer of 2009. Water temperature showed a gradual reduction according to the depth. While the salinity was low in the surface layer showing a mixed down to the relatively subsurface layer, it was increased with an increase in the depth at the middle and bottom layers showing a maximum value at 150~200 m followed by a decreasing aspect afterwards, although the change was not large. The change of sigma-t was governed by the water temperature, and gradually increased in the surface layer with an increase in the depth, showing a value higher than in the surface layer by about 3 $kg/m^3$ at the bottom layer. Although the intensity of light was exponential reduced in the surface layer, the compensation depth was located at the depth of about 80m. The vertical profiles of chlorophyll a concentration was governed by the intensity rather than the changes in water temperature or salinity, exhibiting a maximum value at the compensation depth corresponding to 1% in the surface light intensity. The micro-phytoplankton communities consisted of 56 genera 103 species showing a relatively variety, while the standing crop was also changed to 112.0~470.0 cells/L in the pelagic environment, showing a maximum chlorophyll a concentration. Although a variety of dominant species appear at low dominance without dominant species appearing with a right-wing point in the phytoplankton communities, the silicoflagellate, Otactis otonaris at the station A and the dominance of 26% due to Leptocylindrus mediterraneus at the station C have been judged to be unusual. For community analysis of infinitesimal creatures such as phytoplankton of oligotrophic waters through the present study, ecology studies through vertical sample collection agreeing with the results of continuous observation such as identification of vertical distribution in a marine environment or of maximum chlorophyll layers have been considered rather than a survey method with intervals of a given depth such as surface, subsurface, middle and bottom layers.

Distribution of Microorganisms in the Marine Ranching Ground of Tongyong Coastal Waters (통영 연안 해역에서의 미생물 분포)

  • 장지철;김말남;이진환;김종만
    • Korean Journal of Environmental Biology
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    • v.18 no.4
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    • pp.403-409
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    • 2000
  • Surface and bottom water samples were collected from 10 stations located in the coastal area of Tongyong in April, August and October 2000. Distribution of heterotrophic bacteria, coliform bacteria and fungi in the sea water samples was investigated by measuring the corresponding viable cell number according to the plate counting method. Heterotrophic bacteria in the surface water counted 3.1$\times$10$^2$- 4.0$\times$10$^3$cfu ml$\^$-1/, 2.7$\times$10$^3$- 1.2$\times$10$\^$5/cfu ml$\^$-1/ and 1.3$\times$10$^2$- 7.2$\times$10$^2$cfu ml$\^$-1/ in April, August and October, respectively. The cell number of coliform bacteria in the surface water amounted to 0-1.5$\times$10$^1$cfu ml$\^$-1/, 3.5$\times$10$^1$- 5.2$\times$10$^3$cfu ml$\^$-1/ and 0-1.8$\times$10$^2$cfu ml$\^$-1/ in April, August and October, respectively. As for fungi, the cell number in the surface water was 0-3.0$\times$10$^1$propagules ml$\^$-1/, 3.0$\times$10$^1$- 8.0$\times$10$^1$ propagules ml$\^$-1/ and 0-2.2$\times$10$^1$ propagules ml$\^$-1/ in April, August and October respectively. The surface water samples from the station 3 in August were added with feed stuffs for fish as much as 0.01 gl$\^$-1/, 0.1 gl$\^$-1/ and 1 gl$\^$-1/ and cultured at 5$\^{C}$, 15$\^{C}$, 25$\^{C}$ and 35$\^{C}$. Microbial cells were not isolated at all when the culturing temperature was 5$\^{C}$. However, the microbial cell number increased significantly in all the surface water samples containing 1 gl$\^$-1/ of the feed stuffs when cultured at 15$\^{C}$, 25$\^{C}$ and 35$\^{C}$

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Spatio-temporal Distributions of Organic Matter in Surface Sediment in the Central Part of the South Sea, Korea (남해 중부해역 표층퇴적물 유기물의 시.공간 분포특성)

  • Noh, Il-Hyeon;Yoon, Yang-Ho;Park, Jong-Sick;Soh, Ho-Young;Kim, Dae-Il
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.9 no.4
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    • pp.203-215
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    • 2006
  • Field observations on the spatio-temporal distribution of organic matter of the surface sediment were carried out at 15 stations in the central parts of the South Sea of Korea from April 2002 to January 2003. The range of water temperature and salinity in bottom waters, mud content and water content of surface sediment were $8.06{\sim}23.35^{\circ}C,\;29.20{\sim}34.51\;psu,\;71.2{\sim}99.9%$ and $38.7{\sim}68.9%$, respectively. Measured parameters on the surface sediments of ignition loss (IL), chemical oxygen demand (CODs), phaeopigment, particulate organic carbon (POC) and particulate organic nitrogen (PON) also ranged in $3.9{\sim}l2.5%,\;9.60{\sim}44.05\;mgO_2/g-dry,\;1.58{\sim}29.51\;{\mu}g/g-dry,\;3.12{\sim}13.01\;mgC/g-dry$ and $0.49{\sim}2.00\;mgN/g-dry$, respectively. The spatio-temporal distribution of organic matter demonstrated higher concentrations offshore than at lesions near the coastal line. Higher concentrations occurred in the summer and spring. The results indicated that the origin of organic matter in surface sediments in the central part of the South Sea was autochthonous rather than allocthonous because the organic matter had an average C/N ratio of 6.44 (${\pm}0.51$). However, the composition of autochthonous organic matter was mainly derived from detritus rather than living phytoplankton, which was Indicated by the results of the POC/phaeopigment ratio. A principal component analysis (PCA) indicated that 73.2% of the variability in the data was described by two factors: 1) an 'environmental factor concerning the accumulation of materials (57.3%)' and 2) 'origin of organic matter and the composition by primary production (15.9%)'. The sedimentary environment in the central part of the South Sea was divided into four regions from the factor score of the PCA by the concentrations of organic matter and the composition ratio of organic matters from phytoplankton in surface sediments.

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Regeneration Processes of Nutrients in the Polar Front Area of the East Sea III. Distribution Patterns of Water Masses and Nutrients in the Middle-Northern last Sea of Korea in October, 1995 (동해 극전선역의 영양염류 순환 과정 III. 1995년 10월 동해 중부 및 북부 해역의 수괴와 영양염의 분포)

  • CHO Hyun-Jin;MOON Chang-Ho;YANG Han-Seob;KANG Won-Bae;LEE Kwang-Woo
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.30 no.3
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    • pp.393-407
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    • 1997
  • A survey of biological and chemical characteristics in the middle-northern East Sea of Korea was carried out at 28 stations in October, 1995 on board R/V Tam-Yang. On the basis of the vertical profiles of temperature, salinity and dissolved oxygen, water masses in the study area were divided into 5 major groups; (1) Low Saline Surface Water (LSSW), (2) Tsushima Surface Water (TSW), (3) Tsushima Middle Water (TMW), (4) North Korean Cold Water (NKCW), (5) last Sea Porper Water (ESPW). Other 4 mixed water masses were also observed. It is highly possible that the LSSW which occured at depths of $0\~30m$ in the most southern part of the study area is originated from the Yangtze River (Kiang) of China due to very low salinity $(<32.0\%_{\circ})$ relatively high concentration of dissolved silicate and no sources of freshwater input into that area. Oxygen maximum layer in the vertical profile was located near surface at northern cold waters and became deeper at the warm southern area. Oxygen minimum layer af depths $50\~100m$, which is TMW, were found in only southern area. In the vortical profiles of nutrients, the concentrations were very low in the surface layer and increased drammatically near the thermocline. The highest concentration occurred in the ESPW. The relatively low value of Si/P ratio in the ESPW (13.63) compared to other reports in the East Sea was due to continuous increase of P with depth as well as Si. The N : P ratio was about 6.92, showing that nitrogenous nutrient is the limiting factor for phytoplankton growth. The exponential relationship between Si and P, compared to the linear relationship between N and P, indicates that nitrate and phosphate have approximately the same regenerative pattern, but silicate has delayed regenerative pattern.

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Variations in subtidal surface currents observed with HF radar in the costal waters off the Saemangeum areas (새만금 연안역에서 HF radar에 의해 관측된 조하주기 표층해류의 변화)

  • Kim, Chang-Soo;Lee, Sang-Ho;Son, Young-Tae;Kwon, Hyo-Keun;Lee, Kwang-Hee;Choi, Byoung-Hy
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.13 no.1
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    • pp.56-66
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    • 2008
  • Subtidal surface currents are derived from HF radar measurements in the Saemangeum coastal ocean of the Yellow sea in July 2002 and from September to November 2004. The surface current field is analyzed to examine the effect of wind, river plume and coastline change on the spatial distribution and temporal variation of the surface currents. In July 2002, average wind speed was 0.5 m/s and freshwater discharge from the Keum River was $0.88{\times}10^7\;ton/day$. Temporal mean currents ($\overline{U}$) flow to the northwest with speed of $7{\sim}10\;cm/s$ near the Keum River estuary, to the west as fast as 13 cm/s near the opening gap of the Saemangeum $4^{th}$ dyke, and to the northwest off the Gogunsan-archipelago. This flow pattern is a result of the Keum River plume dispersal and tide-residual currents from the opening gap of the Saemangeum $4^{th}$ dyke. Time series of spatially-averaged current (<$U-\overline{U}$>) direction is highly (r=0.98) correlated with wind direction. From September to November 2004, the opening gap of the Saemangeum $4^{th}$ dyke was closed, northwesterly wind blew with speed of 2.5 m/s on average and the Keum River discharge was $1.19{\times}10^7\;ton/day$. Temporal mean current field ($\overline{U}$) has weak surface flow in most of the coastal ocean and relatively strong currents flow to the southwest with speed of 10 cm/s along the shape coastline of the Gogunsan-archipelago and the Saemangeum $4^{th}$ dyke. The strong flow is generated by the prevailing northwesterly wind which pushes the Keum River plume toward the Saemangeum $4^{th}$ dyke. The residual currents from the opening gap of the Saemangeum $4^{th}$ dyke disappeared and correlation coefficient between time series of spatially-averaged current () direction and the wind direction is 0.69.

Study on Physical Oceanographic Environments in the Coastal Sea of Chung-Moon, Cheju Island (제주도 중문 연안역의 물리해양환경에 대한 연구)

  • Hong, Chang-Su;Oh, Kyung-Hee;Pang, Ig-Chan
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.6 no.4
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    • pp.211-217
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    • 2001
  • Physical oceanographic environments in the coastal sea of Chung-Moon located in the south coast of Cheju Island, Korea, where water pollutions by growing tourism complex possibly start to influence on the ecological system, are studied with hydrographic data observed monthly during July 1997 to June 2000. Winter and summer characteristics are shown in December to April and June to October, respectively, and transitional characteristics are shown in May and November. Waters show 14{\sim}16^{\circ}C$ and 34${\sim}$34.7 psu in winter and $15{\sim}27^{\circ}C$ and 32${\sim}$34.3 psu in summer. It tells that Tsushima water distributes in the whole column in winter and in the lower layer in summer, and Yangtze coastal water appears in the surface water in summer. When the influence of Yangtze coastal water is strong, salinities below 30psu are shown. Stratification is formed in the depth of about 20 m from June to October, so that it is not shown in the near shore stations, of which the depth is about10 m. Isotherms and isohalines sometimes tend to be perpendicular to the coast line in the surface, which seems to show influences from the steam power plant near St. 1 and the sewage disposal plant near St. 3. During the observation period, temperatures in St. 1 are a little higher than those in St. 2 and St. 3 except for a couple of months in summer and salinities in St. 3 are mostly a little lower than those in St. 1 and St. 2. Their effects seem to be no more than $0.4^{\circ}C$ in a distance of 300 m and no more than 0.1 psu within a distance of 30 m.

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Ultra Dry-Cleaning Technology Using Supercritical Carbon Dioxide (초임계 이산화탄소를 이용한 초순수 건식 세정기술)

  • Joung, Scung Nam;Kim, Sun Young;Yoo, Ki-Pung
    • Clean Technology
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    • v.7 no.1
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    • pp.13-25
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    • 2001
  • With fast advancement of fine machineries and semiconductor industries in recent decades, the ultra-cleaning of organic chemicals, submicron particles from contaminated unit equipments and products such as silicon wafers becomes one of the most important steps for further advancement of such industries. To date, two kinds of ultra cleaning techniques are used; one is the wet-cleaning and the other is the dry cleaning. In case of wet cleaning, removal of organic contaminants and submicron particles is made by DIW with additives such as $H_2O_2$, $H_2SO_4$, HCl, $NH_4OH$ and HF, etc. While the wet cleaning method is most widely adopted for various occasions, it is inevitable to discharge significant amount of toxic waste waters in environment. Dry cleaning is an alternative method to mitigate environmental pollution of the wet cleaning with maintaining comparable degree of cleaning to the wet cleaning. Although there are various concept of dry cleaning have been devised, the dry cleaning with environmentally-benign solvent such as carbon dioxide proven to show high degree of cleaning from the contaminated porous surface as well as from the bare surface. Thus, special global attention has been placing on this technique since it has important advantages of simple process schemes and no environmentally concern, etc. Thus, this article critically reviews the state-of-the-art of the supercritical fluid drying with emphasis on the thermo-physical characteristics of the supercritical solvent, environmental gains compared to other dry cleaning methods, and the generic aspects of the basic design and processing engineering.

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A Study on Chemical Compositions of Sediment and Surface Water in Nakdong River for Tracing Contaminants from Mining Activities (광해오염원 추적을 위한 낙동강 지역 퇴적물 및 하천수의 화학조성 연구)

  • Kim, Jiyun;Choi, Uikyu;Baek, Seung-Han;Choi, Hye-Bin;Lee, Jeonghoon
    • Journal of the Korean earth science society
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    • v.37 no.4
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    • pp.211-217
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    • 2016
  • There have been found mine tailings, wastes, and mining drainage scattered in the area of Nakdong River due to the improper maintenance of the abandoned mines. These contaminants can flow into rivers during the heavy rain periods in summer. Along the study area beginning Seokpo-myeon, Bonghwa-gun of Gyeongsangbuk-do untill Dosan-myeon, Andong-si, there are one hundred five mines including sixty metalliferous mines and forty-five nonmetal mines, which can adversely affect the adjacent rivers. To verify the contamination, we collected sediments, seepage water and surface water for a year both in rainy season and dry season. This study found that sediments, containing high concentrations of heavy metals caused by mining activities, are dispersed throughout the entire river basin (68 sample points with pollution index, based on the concentration of trace element, (PI) >10 among the total of 101 samples). The results of river water analysis indicated the increased concentrations of arsenic and cadmium at branches from Seungbu, Sambo, Okbang and Janggun mine, which concerns that the river water may be contaminated by mining drainage and tailing sediments. However, it is difficult to sort out the exact sources of contamination in sediments and waters only by using the chemical compositions. Thus the control of mining pollution is challenging. To prevent water from being contaminated by mining activities, we should be able to divide inflow rates from each origin of the mines. Therefore, there should be a continued study about how to trace the source of contaminants from mining activities by analyzing stable isotopes.