• Journal of Life Science
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• v.15 no.4 s.71
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• pp.578-583
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• 2005

Cell-free culture broth of marine halophilic bacterium, Kordia algicida was shown to possess specific algicidal ability against red tide organism, Cochlodinium polykrikides. Physiochemical characteristics of algicidal material originated in the bacterial culture broth were analyzed that its molecular weight was estimated to a 3,000 dalton and it was stable in heat and pH treatment. The algicidal fraction against C. polykrikoides obtained from gel permeable chromatography contained high concentration of ammonium ion as analyzed by ICP/Mass spectrum. C. polykrikoides by the fraction was quickly lysed within 1 min. It was shown that the effective concentration for algicide against C. polykrikoides was over 1mM of ammonium chloride. On the other hand, other metal ions presented in the algicidal fraction showed no algicidal effect against C. polykrikoides. In additon, ammonium ion exhibited species-specific killing spectrum for two species of red tide organisms, C. polykrikoides and Gymnodinium sanguieum. Therefore, further researches on the killing mechanism against C. polykrikoides exerted by ammonium ion, and subsequent development of replaceable algicidal materials will perform to provide useful tools for the control of red tide.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.606-609
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• 2000

These results indicate that the low-Sequency signal of T/P data (with periods greater than 200 days) can be interpreted most safely. Similarly to the case of the T/P data, corrections were also applied to those of tide gauge counterparts. Hence, when the 200-day effect was filtered out, the agreement between T/P and TG data sets was optimized.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.2
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• pp.222-226
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• 2017

It is well known that typhoons strongly influence marine ecosystems. For example, red tides nearly disappear after the passage of typhoons, although the physical or biological mechanism underlying this has not been elucidated. Here, a particle tracking model is executed in a three-dimensional primitive equation model to understand the process of red tide extinction after the passage of a typhoon. Red tide organisms may be regarded as tracers because they have limited mobility and thus their behavior is governed entirely by currents. Initially, tracers are randomly scattered within a limited area, and their spatial and temporal behavior is tracked during and after the passage of a typhoon. This model suggests that the extinction of red tides is significantly influenced by momentum disturbances caused by the typhoon.

• Journal of Environmental Science International
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• v.9 no.6
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• pp.463-468
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• 2000

Ther effect of UV on the mortality rate of toxic dinoflagellate Amphidinium Carterae causing a red tide in the coastal area of korea was investigated in the batch and continuous-scale reactor equipped with ultraviolet irradiation-apparatus. Degussa P(sub)25 titanium oxide, a photocatalyst proved to be effective of the mortality of Amphidinium Carterae supplied with photocatalyst and UV radiation were greater than 95% in 2 minutes of UV radiation and the rate were higher than that by UV-radiation without titanium dioxide in the batch and continuous-flow scale reactor, The mortality time of Amphidinium Carterae increased with the cell density under UV-illumination in the batch scale reactor. The mortality rate in the density of $5.0$\times$10^4$ cell/mL at the same experimental condition was more than 90% in 4 minutes in the continuous flow scale reactor. The percentage of 99.9$\pm$0.1% of Amphidinium Carterae in the density of $0.5$\times$10^4$ cells/mL was died in 20 minutes when the phytoplankton was illuminated with UV-radiation without photocatalyst.

• Journal of Ocean Engineering and Technology
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• v.12 no.3 s.29
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• pp.1-8
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• 1998

The purpose of this study is to determine the distribution of the suspended matter caused by dredging at the northeastern part of Kwangyang Bay and to determine the effect of the single silt protector for it. According to the direction of the tidal current, six sampling stations were chosen from the dredging site to the southeast. At the high tide, the high concentration of the suspended matter was observed below the mid-depth near the dredging site. As the tidal currents were stronger. its concentrations below the mid-depth at the inner stations of the single silt protector were rapidly increased, but those of the outer stations did not show any significant change. The concentrations at the inner stations of the silt protector at that time were from 20~140mg/l and those of the outer stations, which was only about 30 m apart from the inner station, were from 20~30mg/l. It suggests that the large amount of suspended matter caused by dredging were moved to the inner stations near the silt protector at the ebb tide and that the silt protector is very effective for the suspended matter.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.4 no.4
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• pp.249-253
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• 2000

Data obtained from a cruise from 4~12 December, 1998 was analyzed to estimate the mixing effects of wind, surface cooling, and tide. A band denoting a mixing area with a temperature difference of less than 1$^{\circ}C$ between the sea surface and the bottom extended 40~60 km from the coast into the open sea, following 125$^{\circ}$ 30\` E in longitude. This band was divided into two areas; a well-mixed area close to the coast and a stratified region in the open sea. The mixing effect due to the wind was only 2%, yet the mixing effect due to the tides was about 68%. This indicates that surface cooling and tides were the major factors involved in the mixing mechanism on the west coast during the cooling season.

• Journal of Environmental Science International
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• v.11 no.6
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• pp.519-528
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• 2002

This study was to evaluate the impact of river runoff and salt intrusion by tide on nutrient balance of estuary during a complete tidal cycle. 24 hours time series survey was carried out during a spring tide July 2001 on a tidal estuary in the Keum river. Three stations(A,B,C) were set along a transect line of about 10km, which linked the lower part of estuary dyke to the subtidal zone. Surface water was sampled simultaneously at each station every hours f3r the determination of nutrients. Water temperature, pH and dissolved oxygen were measured in situ. Riverine input of silicate and nitrate during ebb tide significantly increased the concentration of all stations. Conversely, during high tide, nutrient concentration were lowered by the mixing of fresh water with sea water Ammonium nitrogen concentration were higher at intertidal zone(Stn.B) due to sewage inflow to Kyeongpo stream and ammonium release under anaerobic conditions. Also, these results was discussed as a biological component that influences the processes of nutrient regeneration within the estuary. Best correlations were found at lower part of estuary dyke(Stn.A) for salinity against DIN(Y=0.121 Sal.+4.97, r2=0.956) and silicate(Y=0.040 Sal.+2.62, r2=0.785). But no significant correlation was found between salinity and ammonium. Unbalanced elemental ratio(N/P, Si/N and Si/P) depended significantly on the import of nutrients (silicate & nitrate nitrogen) from river and stream. The effect of the tidal cycle and river runoff is important that in determining the extend of the variations in nutrient concentrations at all station.

• 한국해양학회지
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• v.5 no.1
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• pp.30-36
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• 1970

The water quality of the laver bed at Yongwon Ri, Changwon Gun was investigated during the spring and neap tide in March 1970. The effect of tide on the contents of various chemical constituents was irregular and the variation ranges of the contents were narrow. The pH value during flood and ebb tide was a constant of 8.2. The chlorosity range varied from 19.15 to 19.33g/l, the difference of 0.18g/l being comparatively small for coastal waters. The nutrient salts contents varied irregulary with the change in tide, but nitrite and soluble iron were not detected. In local distribution, chlorosity and silicate- silicon contents were found to be more at Sts. 1, 2 and 3 in the eastern area than at Sts. 4, 5 and 6 in the western area, wheras nitrate and ammonia contents were found to be more at Sts. 4, 5 and 6. The nitrate content was especially high, being twice as much as that at Sts. 1, 2 and 3 in the eastern area. In the spring tide, chlorosity was found, on the average, to be as much as 0.06g/l higher than in the neap tide, but the contents of nutrient salts were higher in the neap tide, especially the nitrate content was twice as much. When compared with other selected local laver beds, i.e., the tidal flats of the Nackdong and Somjin rivers, and of Wan Do Gun, the chlorosity level was highest but the nutrient salts contents level was, in general, slightly lower and the variation ranges narrow in the laver bed at Yongwon ri. The nitrate content, in particular was one tenth smaller than the others.

• The Korean Journal of Zoology
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• v.9 no.1
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• pp.1-6
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• 1966

Frequently , large masses of the young short necked clam, Tapes japonica , die at their tidal flats in summer and this phenomenon has not been explained clearly. The purpose of the present investigation is to study the thermal condition and the chlorinity level of tidal flats in which the young clam appears to be injured. A study is also mad efor the burrowing organism in the lower layer of the esturay over which the fresh water flow during the low tide. Observation are made at five places of the tidal flat near Ikawazu Fixheries Laboratory of Tokyo University during the ebb and flow tide period of the spring tide. The diurnal and monthly changes of tidal temperatures and chlorinities are measured. Results of the study are ; 1. The surface temperature of the tidal flat increases with the ebb tide, reaches the highest between 12-14PM, and gradually decreases thereafter. The temperatures of tidal flat below 5 and 10 cm increase gradually until the flow tide reaches the surface. 2. At the spring tide in summer , the diurnal change of surface of the tidal flat temperature is very extensive ; it reaches 37-39$^{\circ}C$ in August. At the depths of 5 and 10 cm the temperature remains at 33 $^{\circ}C$ and 31$^{\circ}C$ , respectively. 3. The chlorinity of the tidal flat is higher during May through June and lower July through August, and this seems to be related to the amount of rainfall. 4. The chlorinity of the surface of tidal flat increases slightly during the ebb and flow tide periods. The observed higher chlorinity of surface of the tidal flat was 18.82% Cl. 5. At near the esturay, the fresh water that overflows the tidal flat affects the chlorinity of the surface but no such influence to the depth of the flat. 6. From above observations, it is assumed that the young short necked clam in the tidal flat could be exposed to the severe change of environmental conditions. The high temperature of the tidal flat in summer and the low chlorinity of it at flood period may be considered as the change in environment.

• Journal of Korea Water Resources Association
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• v.40 no.10
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• pp.793-800
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• 2007

This research applied to Wavelet transform that have soft resolution time and frequency area for stage of Hadong2 station in order to extract to discharge component by rainfall and tidal level component by tide. Approximation component(A6) of last level for wavelet decomposition displayed the biggest energy value 87.77%, and detail component(D3) energy value was 10.70% with periodicity of semidiurnal tide type(about 12 hours). Also skewness, kurtosis values of D3 have similar to tidal level of Yeosu. Approximation component(A6), Detail component(D6, D5) for Hadong2 stage was runoff component, and detail component(D4, D3, D2) was tide component according to effect of tide.