• Title/Summary/Keyword: Seawater

Search Result 2,752, Processing Time 0.029 seconds

Growth and Survival of Juvenile Grey Mullet (Mugil cephalus) in Rearing System with Recirculated Seawater and Freshwater (순환여과 사육시스템에서 해수와 담수에 사육한 숭어(Mugil cephalus) 치어의 성장과 생존율)

  • 장영진;허준욱;임한규
    • Journal of Aquaculture
    • /
    • v.14 no.1
    • /
    • pp.29-33
    • /
    • 2001
  • Total length and body weight of grey mullet were 6.4cm and 2.1g, respectively at the beginning of the experiment. After 60 days of rearing, body weight of the mullet(363%) was significantly higher in freshwater group than that (187%) in seawater group. However, the condition factor showed no significant differences between seawater (9.0%) and freshwater (8.8%) groups. Survival of the mullet was 98.3% and 64.3% in seawater and freshwater groups, respectively.

  • PDF

Analysis and Quantification of Seawater Infiltration by Wave Action in Coastal Zone (연안해역에서 파도에 의한 해수 침투이론의 비교와 정량화)

  • Cheong Cheong-jo;Choi Doo-hyoung;Kim Tae-keun;Okada Mitsumasa
    • Journal of the Korean Society for Marine Environment & Energy
    • /
    • v.4 no.4
    • /
    • pp.3-11
    • /
    • 2001
  • To know the seawater infiltration into tidal flat sediment in coastal area is very important, because it is significantly correlated with the infiltration and transportation of pollutants in soil, the supply of dissolved oxygen, nutrients and organic matter to benthic organisms for survival of benthic organisms and the seawater purification. So, we set up purpose to clarify the infiltration behavior of seawater by wave action in tidal flat, to clear the effects of slope of tidal flat and breaking wave height on seawater infiltration and to quantify the infiltration volume of seawater. For purpose, the seawater infiltration was studied with visualization method by using coloring tracer and transparent glass beads replaced as natural sediment in model tidal flat. Specific conclusions derived from this study are as follows. The semi-circular type infiltration of seawater by wave action into saturated sediment was a new infiltration behavior that was not considered in previous studies. The infiltration rate of seawater was increased with increasing of breaking wave height and slope of tidal flat. However, the effects of the slope was bigger than that of breaking wave height on seawater infiltration into tidal flat sediments. It was possible to calculate the infiltration volume of seawater by wave action in natural tidal flat sediment and in fields. Therefore, we can point out that wave action play an important role in the supply of dissolved oxygen, nutrients and organic matter to benthic organisms, transportation or diffusion of pollutants and seawater purification. So, we hope to be studied the supply of food to benthic organism, pollutant transport and seawater purification on the base of these results.

  • PDF

A Study on the Thermal and Chemical Characteristics of Wasted Coal for the Development of Low Cost Fuel

  • Lee, G.H.;Shim, J.D.
    • Agricultural and Biosystems Engineering
    • /
    • v.3 no.2
    • /
    • pp.79-84
    • /
    • 2002
  • The seawater involving diverse chemical elements was mixed with wasted coals to improve the quality. The thermal and chemical characteristics of these seawater-mixed coals were investigated and compared with those of original coals. The contents of MgO, $Na_2O$, and $K_2O$ were increased by mixing seawater in wasted coals. The content of $Na_2O$ in these coal samples was greatly increased due to the sodium, which was the main component of seawater. Thus, it was expected that fusion temperatures of these coal samples were decreased. Coal samples mixed with seawater showed that the rapid weight loss was started at the lower temperature than those of original coal samples. In these coal samples, the temperatures of maximum heat emission were lowered by average $61^{\circ}C.$. Thus, it is suggested that some chemical constituents of the seawater act an important role on lowering the ignition temperature of wasted coal. By mixing seawater into wasted coals, the calorific values were increased. Especially, calorific values were greatly increased in the coal samples of lower quality as Baksan A and B with the improvement of 15~20%.

  • PDF

Germicidal Effect of Electrolyzed Seawater on Live Fish and Shellfish (전기분해 해수의 활어패류 살균 효과)

  • Lee, Hee-Jung;Yu, Hongsik;Oh, Eun-Gyoung;Shin, Soon Bum;Park, Kunbawui;Kim, Ji Hoe
    • Korean Journal of Fisheries and Aquatic Sciences
    • /
    • v.46 no.5
    • /
    • pp.534-539
    • /
    • 2013
  • To secure the biological safety of live fish and shellfish for raw consumption, the germicidal effects of electrolyzed seawater were evaluated. Upon direct exposure to electrolyzed seawater, coliform group bacteria were killed and decreased to undetectable levels after 1 day. The physicochemical characteristics of the seawater were stable during the test period. A byproduct of chlorine disinfection, trihalomethane, was not generated by the electrolysis of seawater. Vibrio parahaemolyticus infection in a live fish was effectively resolved by electrolyzed seawater and became undetectable after 12-36 h of treatment. Bioaccumulation of coliform group and fecal coliform bacteria in live oysters Crassostrea gigas was removed within 18 h of treatment. This study demonstrated that electrolyzed seawater is an effective and safe germicidal agent for the traditional retail market and can help to prevent outbreaks of foodborne disease associated with the consumption of raw fish and shellfish.

Characteristics of Foam Generation in Freshwater and Seawater (담수와 해수에서의 포말 생성 특성)

  • SHIN Jeong-Sik;KIM Byong-Jin;SUH Kuen-Hack
    • Korean Journal of Fisheries and Aquatic Sciences
    • /
    • v.37 no.3
    • /
    • pp.179-185
    • /
    • 2004
  • The characteristics of foam generation were assessed for freshwater and seawater using a foam generator. Both in freshwater and seawater, the height of the foam layer increased with initial protein concentrations. The height of the foam layer also increased with pore size of the air distributor. The optimum superficial air velocities (SAV) in freshwater and seawater were 0.84 cm/sec and 0.6 cm/sec, respectively. The height of the foam layer was the highest in pH 3 in freshwater and in the region of pH 5-7 in seawater. The height of the foam layer increased with $NaHCO_3$ concentration in freshwater, and $NaHCO_3$ concentration had little effect in seawater. Removal efficiencies of total suspended solid (TSS) and turbidity decreased with an increase of initial protein concentrations in a batch foam separator both in freshwater and seawater.

Assessment of seawater intrusion using geophysical well logging and electrical soundings in a coastal aquifer, Youngkwang-gun, Korea

  • Hwang Seho;Shin Jehyun;Park Inhwa;Lee Sangkyu
    • Geophysics and Geophysical Exploration
    • /
    • v.7 no.1
    • /
    • pp.99-104
    • /
    • 2004
  • A combination of drilling, geophysical well logging, and electrical soundings was performed to evaluate seawater intrusion in Baeksu-eup, Youngkwang-gun, Korea. The survey area extends for over 24 $km^2$. To delineate the extent of seawater intrusion, 60 vertical electrical soundings (VES) have been carried out. Twelve wells were also drilled for the collection of hydrogeological, geochemical, and geophysical well logging data, to delineate the degree and vertical extent of seawater intrusion. To map the spatial distribution of seawater in this coastal aquifer, geophysical data and hydrogeochemical results were used, and the relation between the resistivity of groundwater and equivalent NaCl concentration was found. Layer parameters derived from VES data, various in-situ physical properties from geophysical well logging, and the estimated equivalent NaCl concentration were very useful for quantitative evaluation of seawater intrusion. Our approach for evaluating seawater intrusion can be considered a valuable attempt at enhancing the use of geophysical data.

A Study on the Corrosion of Cu-Ni Alloy in Chlorinated Seawater for Marine Applications (잔류 염소가 포함된 해수에서의 Cu-Ni 합금의 부식 거동 연구)

  • Jung, Geunsu;Yoon, Byoung Young;Lim, Chae Seon
    • Corrosion Science and Technology
    • /
    • v.17 no.4
    • /
    • pp.176-182
    • /
    • 2018
  • Corrosion of the Cu alloy with 10wt% Ni in stagnant seawater with residual free chlorine was investigated. Despite that fact that Cu alloys are widely used for seawater applications due to their stubborn resistance to chloride attack, not much is known as to how the residual free chlorine in seawater affects corrosion of Cu and its alloys. In this work, immersion tests were conducted in the presence of different levels of chlorine for 90-10 Cu-Ni samples, one of the most frequently used Cu alloys for seawater application, mostly in shipbuilding. The results revealed no evidence for accelerated corrosion of the Cu-Ni alloy even in the presence of 5 ppm residual chlorine in seawater, signifying that the Cu-Ni alloy can be more tolerant to residual chlorine that has been commonly cited by the shipbuilding industry. However, comparison of polarization behavior of the alloy samples in the presence of different electrolytes with different concentrations of residual chlorine suggests that higher concentration of chlorine could increase the corrosion rate of the Cu-Ni alloy. Furthermore, it is suggested that microorganisms in the seawater could increase the corrosion rate of the Cu-Ni alloy by encouraging exfoliation of the corrosion product off the metal surface.

The Application and Evaluation of Heating and Cooling System by Seawater Heat Source for Research Center Building in Jeju (제주지역 연구소 건물의 해수열원 냉난방시스템 적용 및 평가)

  • Park, Jin-Young;Kim, Sam-Uel;Chang, Ki-Chang
    • Journal of the Korean Solar Energy Society
    • /
    • v.33 no.6
    • /
    • pp.26-31
    • /
    • 2013
  • Use of heat from seawater could be different from the weather conditions of a coastal city and seawater temperatures near the city. It will be a good option to use surface layer water with Heat Pump system for using seawater cooling/heating in Jeju. The study investigates the proper depth for seawater heat gain of Jeju area in Korea. Sampling points are 0, 10, 20, 30m from the surface of the Sea. Seawater temperature does not change significantly according to the depth in winter, while the temperature is quite different according to the depth in summer. In this study, it is analyzed to compare existing system and seawater heat source system for target buildings on Jeju. And this systems are calculated a initial cost.

Corrosion Behavior of Carbon Steel in Diluted Sulfuric Acid based on Seawater

  • Kim, Mun Su;Jeong, Jin-A
    • Corrosion Science and Technology
    • /
    • v.18 no.3
    • /
    • pp.78-85
    • /
    • 2019
  • The International Maritime Organization (IMO) will administer a new 0.5% global sulfur cap on fuel content from 1 January 2020, lowering from the present 3.5% limit. Seawater $SO_x$ (sulfur oxide) scrubbing is especially spray scrubbing and a promising alternative to complying with the IMO regulation. However, the ionization of $SO_2$ (sulfur dioxide) and the $H_2SO_4$ (sulfuric acid) formed from $SO_3$ (sulfur trioxide) is proposed to accelerate corrosion of the internal seawater pipe. Apparently, the corrosion of the scrubber seawater piping system occurs in a severe and frequent manner. Hence, in this study, electrochemical measurement and weight loss of carbon steel (used as seawater pipe in most of the ships) in diluted sulfuric acid solution were investigated to determine corrosion rate, corrosion current density, corrosion potential, electrochemical behavior, and impressed-current density. Accordingly, the corrosion rate of carbon steel sheet in various diluted sulfuric acid solutions was observed to be greater than that in natural seawater, thus suggesting the fundamental data to deal with corrosion problems in scrubber seawater pipe.

Investigation of water qualities and microbials on the flow-through olive flounder, Paralichthys olivaceus farms using coastal seawater and underground seawater in Jeju (연안해수와 지하해수를 사용하는 제주 넙치 양식장의 수질과 미생물 변동)

  • KIM, Youhee
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.58 no.1
    • /
    • pp.59-67
    • /
    • 2022
  • This study assessed the levels of water qualities and microbials contamination of inland olive flounder farms in Jeju in the summers from 2015 to 2017. Three farms (A-C) located in a concentrated area using mixing coastal seawater and underground seawater and one farm (D) located in an independent area using only coastal seawater were selected. Total ammonia nitrogen (TAN) reached a maximum of 0.898 ± 1.024 mg/L as N in the coastal seawater of A-C, which was close to the limit of the water quality management goal of the fish farm. TAN in the influent from A-C was up to three times higher than that of D, so that the discharged water did not spread to a wide range area along the coast and continued to affect the influent. TAN of the effluent in A-C increased by 2.7-4.6 times compared to the influent, resulting in serious self-pollution in the flounder farm. Heterotrophic marine bacteria in the influent of A-C was about 600 times higher than D, and the discharge of A-C was increased by about 30 times compared to the influent.