• Korean Journal of Environmental Biology
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• v.27 no.3
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• pp.306-313
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• 2009

In the Upo wetland, physico-chemical factors were observed during the period from March 2005 to December 2007 on a monthly basis. In the Upo wetland, water temperatures ranged $3.4{\sim}34.5^{\circ}C$. Conductivities were in the range of 133~806 ${\mu}S\;cm^{-1}$, which showed about 140 ${\mu}S\;cm^{-1}$ below in comparison with the precedent studies. The pH levels were between 6.7~9.1 with lower level in summertime. The dissolved oxygens were between 0.06~18.23 mg $L^{-1}$. COD ranged 4.9~20.8 mg $L^{-1}$, and showed a tendency to decrease every year. Nitrogen nutrients such as nitrate nitrogen ($NO_3-N$), ammonia nitrogen ($NH_3-N$) and total nitrogen (T-P) showed that they were generally decreased in comparison with those in the precedent studies. However the total nitrogen (T-N) is still considerably higher than the standard concentration level of eutrophication and algal blooming. Phosphate phosphorus ($PO_4-P$) and total phosphorus (T-P) were also shown as to be reduced considerably comparing with the values in the precedent studies. However, It was found out that total phosphorus (T-P) was dissolved over the criteria concentration of eutrophication. The average of TN/TP ratio was 18 in the Upo wetland, which proved that phosphorus was the limiting factor to the growth of phytoplankton in the Upo wetland. The chl-$\alpha$ was the highest in wintertime and the lowest in summertime, and especially in 2006 summer when the cyanobacterial bloom developed, it showed extremely high concentration.

• Journal of Korean Society on Water Environment
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• v.26 no.4
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• pp.614-621
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• 2010

A indigenous freshwater bivalve Unio douglasiae was introduced to compare the differences in the efficacy of algal bloom control and the appearances of mussel-mediated adverse effects between two different reservoirs such as mesotrophic (Shingu r.) and hypertrophic (Seokmun r.). We constructed the study mesocosm in the shore of each reservoir, stocked the mussel at density of $30indiv./m^3$ for 7 days, and measured daily the phytoplankton density and water quality. In mesotrophic reservoir, even though approximately 38% of suspended solids and chlorophyll-a was reduced by stocked bivalves for the first 3 days, algal density, ammonia and soluble reactive phosphorus gradually increased with increasing mussel death. In hypertrophic reservoir, mussels strongly inhibited suspended solids and chlorophyll-a by the termination of study with no increase of mussel death and nutrient, especially ammonia concentration. In both reservoirs, a strong selectivity showed mussels preferred to diatom rather than cyanobacteria and green algae without algal density and nutrient level. Our results indicate that an introduction of freshwater bivalve U. douglasiae is more strategic to improve water quality of hypertrophic than mesotrophic reservoir, but many preliminary studies on the treatment method and the selection of target water system are required.

• Ocean and Polar Research
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• v.35 no.2
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• pp.147-155
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• 2013

The purpose of this study is to investigate seasonal difference in linear trends in satellite-derived chlorophyll-a concentration (Chl-a) and their related environmental changes in the South Sea of Korea (SSK) and East China Sea (ECS) for recent 15 years (Jan. 1998~Dec. 2012) by analyzing climatological data of Chl-a, Rrs(555), sea surface wind (SSW) and nutrient. A linear trend analysis of Chl-a data reveals that, during recent 15 years, the spring bloom was enhanced in most of the ECS, while summer and fall blooms were weakened. The increased spring (Mar. - May) Chl-a was associated with strengthened winter (Dec. - Feb.) wind that probably provided more nutrient into the upper ocean from the deep. The causes of decreased summer (Jun. - Aug.) Chl-a in the northern ECS were uncertain, but seemed to be related with the nutrient limitation. Recently (after 2006), low-salinity Changjiang diluted water in the south of Jeju and the SSK had lower phosphate that caused increase in N/P ratio with Chl-a decrease. The decreased fall (Sep. - Nov.) Chl-a was associated with weakened wind that tends to entrain less nutrient into the upper ocean from the deep. This study suggests that phytoplankton in the ECS differently changes in response to environmental changes depending on season and region.

• Microbiology and Biotechnology Letters
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• v.34 no.1
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• pp.1-6
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• 2006

Harmful algal blooms (HABs or red tides), caused by uncontrolled proliferation of marine phytoplankton, impose a severe environmental problem and occasionally threaten even public health. We sequenced the genome of an EPS-producing marine bacterium Hahella chejuensis that produces a red pigment with the lytic activity against red-tide dinoflagellates at parts per billion level. H. chejuensis is the first sequenced species among algicidal bacteria as well as in the order Oceanospirillales. Sequence analysis indicated a distant relationship to the Pseudomonas group. Its 7.2-megabase genome encodes basic metabolic functions and a large number of proteins involved in regulation or transport. One of the prominent features of the H. chejuensis genome is a multitude of genes of functional equivalence or of possible foreign origin. A significant proportion (${\sim}23%$) of the genome appears to be of foreign origin, i.e. genomic islands, which encode genes for biosynthesis of exopolysaccharides, toxins, polyketides or non-ribosomal peptides, iron utilization, motility, type III protein secretion and pigment production. Molecular structure of the algicidal pigment was determined to be prodigiosin by LC-ESI-MS/MS and NMR analyses. The genomics-based research on H. chejuensis opens a new possibility for controlling algal blooms by exploiting biotic interactions in the natural environment and provides a model in marine bioprospecting through genome research.

• Korean Journal of Ecology and Environment
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• v.46 no.2
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• pp.225-233
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• 2013

We examined the effect of different field temperatures on water quality improvement (WQI) of natural domestic plant-mineral composites (PMCs). This method was previously used by Kim et al. (2011), to monitor the restoration of water quality of a eutrophic lake, Lake Shingal (Korea). Results indicate that PMCs on phytoplankton, BOD and phosphorus showed more than 70% WQI below $20^{\circ}C$, and less than 40% WQI over $25^{\circ}C$, respectively. The WQIs of PMCs on blue-green algae were gradually decreased with the increase of temperature, whilst diatoms exhibited more than 90% higher WQIs, regardless of water temperature. Additionally, the WQIs on bacterial biomass and total nitrogen were low at all temperatures. These results collectively indicate that water quality improvement activity of plant-mineral composites was dependent on the water temperature, and that the field application of above chemical during temperatures over $25^{\circ}C$, would be less effective in treating a cyanobacteria bloom dominated by Microcystis aeruginosa, than by diatoms.

• 한국해양학회지
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• v.28 no.3
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• pp.186-191
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• 1993

Scrippsiella trochoidea is a dinoflagellate responsible for red tide in early spring in southern coastal water. Marine bacteria appear to exert critical roles on the development and decay of phytoplankton bloom in marine ecosystem. It is likely that marine bacteria, Pseudomonas spp., share some metabolic processes with S. trochoidea. To investigate interactions between S. trochoidea and Pseudomonas spp. directly, cysts of S. trochoidea isolated from the bottom mud in Masan Bay have been germinated and cultured. From the S. trochoidea cultured medium, we have isolated Pseudomonas spp., a dominant and cultured. From the S. trochoidea cultured medium, we have isolated Pseudomonas spp., a dominant species. Both of Pseudomonas spp. and S trochoidea have been simultaneously inoculated into the sterilized sea water and cultured to examine the change of fatty acids. The major fatty acids that showed increases in composition during the dispecific culture were $C_{18:0/},{\;}C_{20:5}{\;}and{\;}C_{22:5}$ in S. trochoidea, and in Pseudomonas spp. Especially, $C_{20:5}{\;}and{\;}C_{18:0}$ were increased in S. trochoidea but decreased in Pseudomonas spp. These results strongly suggest that two species share some processes in their fatty acid metabolism.

• Journal of Environmental Health Sciences
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• v.11 no.1
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• pp.15-28
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• 1985

In order to analyze the water quality in artificial lakes in Chonnam area, a chemical and biological examination of Dongbock Lake and Changsung Lake was conducted from September to December 1983 and May 1984. A summary of the surveyed results is as follows 1. In Dongbock Lake, pH ranged from 7.2-8.1, D.O.: 8.2-12.6mg/l, B.O.D.: 4.4-22.1 mg/l, C.O.D.: 1.0-3.4rag/l, Cl$^-$: 5.9-11.9mg/l, Total-P: 0.001-0.071 mg/l, and Total -N: 0.016-0.697 mg/l, respectively. 2. In Changsung Lake, pH ranged from 7.2-8.1, D.O.: 8.1-9.8mg/l, B.O.D.: 0.9-2.9mg/l, C.O.D.: 1.9-3.4mg/l. Total- P: 0.006-0.016mg/l and Total -N:0.006-0.033mg/l, respectively. 3. The Phytoplankton identified in this investigation were distributed in a total of 46 genera and 76 spedes in Dongbock Lake 37 genera and 45 species in Changsung Lake. 4. In Dongbock Lake, it was found that the dominant algae were Melosira sp., Microcystis sp. and Synedra sp. in September Melosira sp. and Microcytis sp. in October, but Cymbella sp., Naviculla sp. and Nitzschis sp. were also observed in OctoberAsterionella sp., Melosira sp. and Microsystis sp. in November and Melosira sp., Asterionella sp sp. and Synedra sp. in December 1983. 5. In Changsung Lake, it was found that the dominant algae were Melosira sp., Lyngrbya sp. and Microcystis in September Melosira sp. and Synedra sp. in October and November and Melosira sp., Lyngbya sp. and Asterionella sp. in December 1983. The dominant algae were Melosira sp., Lyngbya sp. and Euglena sp. in May 1984. 6. It was found that the dominant algae in both Dongbock and Changsung Lakes were Microcystis sp., Melosira sp. and Asterionella sp.. Which are strongly related with water-bloom. Therefore, it could be suggested that the eutrophication phenomena is going to occur very easily in Dongbock Lake and possibly in Changsung Lake.

• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.95-100
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• 1998

The purpose of this study is to describe the change of the spring bloom and oceanographic condition. The variation of pigment concentration derived from the satellite ocean color data has been analyzed. According to the movement of blooming area, blooming was very concerned with a rising trend of sea surface temperature and a supply of nutrients. A nutrient rich water carried by the Oyashio encounters with the warm Core ring, where mixings and blooms are observed. We examined the correlation by using the satellite observations of the temperature and chlorophyll-a for the spring seasons (May, June, July) of 1998 the off Sanriku area (38-43N, 141- l50E). Using the SeaWiFS data, we process the data into the level-3, which contains the geophysical value of chlorophyll-a. And chlorophyll-a data is mapped for the water between 110E and 160E, and 15N and 52N with a 0.08 * 0.05 degree grid for each image. And Sea Surface Temperature (SST) data is produced using the AVHRR onboard the NOAA. The SST is derived by the MCSST. Then, the data is mapped for the water as much as chi-a data. And these gridded image was made by detection of each water masses, which are Kuroshio Extension, the warm-core ring and the Oyashlo Intrusion, etc., using those satellite images to determine short term change. Off Sanriku is a place where warm-water pool and the Oyashio at-e mixed. When warm streamer has intruded in cold water, the volume of phytoplankton increases at the tip of warm streamer. Warm water streamer was trigger of occurring blooming. And also, SeaWiFS images provided as much information for the studies of chlorophyll-a concentrations in the surface.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.4
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• pp.938-945
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• 2004

On the relationship between the red tide occurrence and the oceanographic factors in the middle coastal area in the South Sea of Korea, the favorable oceanographic conditions for the red tide formation are considered as follows； the calm weather increases sea water temperature in summer and early-fall which the red tide occurs frequently, and the heavy precipitation brings some riverine water to ween: low salinity, high suspended solid, low phosphorus and high nitrogen, respectively. We decided the potential areas in the coastal zones vulnerable to the red tide occurrence based on the limited factors controlling the growth of phytoplankton. By using GIS through the overlap for three subject figures (phosphorus, nitrogen and suspended solids), it was founded that the potential areas are the Yeosu∼Dolsan coast, the Gamak bay, the Namhae coast, the Narodo coast, the Goheung and Deukryang bay. This result has very well coincided to the results of the satellite and in-situ data.

• Korean Journal of Environmental Agriculture
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• v.34 no.1
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• pp.14-20
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• 2015

BACKGROUND: Contamination of source water by odorous compounds are one of the problems related to the water quality management, especially in Korea where surface water is used as drinking water. Geosmin (1, 10-trans-dimethyl-trans-9-decalol) and 2-MIB (2-methyl isoborneol : 1,2,7,7-tetramethyl-exo-bicycloheptan-2-ol) are commonly recognized earthy-musty odor compounds produced by algae causing serious problems to the drinking water purification facilities. METHODS AND RESULTS: In this study, spatial and temporal distribution of the odor compounds, geosmin and 2-MIB were investigated along with the development of phytoplankton in the Daechung reservoir from July 2012 to October 2013. CONCLUSION: Concentrations and frequencys of detection of both compounds increased from April to October which were related to cyanobacterial bloom periods. However, concentrations of odor compounds were not related to the number of cyanobacteria. Concentrations of both cyanobacteria and geosmin showed similar trends with depth. Pearson correlation analyses showed that geosmin concentration exhibited significant correlation with the count of Anabaena macrospora and Aphanizomenon flos-aquae. On the other hand, 2-MIB concentration showed a significant correlation with the count of Anabaena smithii.