• Korean Journal of Ecology and Environment
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• v.45 no.3
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• pp.302-313
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• 2012

Long-term trends (e.g. 1997~2010) of chlorophyll a and water quality properties of the Yeongsan River were analyzed by using water quality monitoring data collected by the water information system, ministry of environment. Nine monitoring stations were selected along the main channel of the river, and parameters of BOD, COD, TN, TP, conductivity, TSS and chlorophyll a were collected for surface water monthly through the monitoring system. Trends of water quality and chlorophyll a were analyzed by the Seasonal Mann-Kendall Test and LOWESS (Locally Weighted Scatter-plot Smoother). The results showed that the water quality parameters, including chlorophyll a, were improved in all stations except Station WC in the most-upper region, where water quality data for the determined parameters were increased, indicating a reduction in water quality. Based on the results from LOWESS analysis, chlorophyll a (algal blooms), BOD and COD recently began to increase after 2007 suggesting that an additional study on the cause of these increases in organic pollution, as well as a better management system for the region are required.

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.4
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• pp.120-140
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• 2013

We investigated the occurrence of red tide, harmful algal blooms(HABs), at the end of 14th century until the beginning of 19th century recorded in the Annals of the Joseon Dynasty, which are the authentic and encyclopedic annual records of the Joseon Dynasty of Korea. In total, 81 cases of HABs are recorded in the annals for which authors draw a table and maps. The number of HABs occurrence at each sea is as follows: 68 times at the South Sea; 50 times at the East Sea; and 23 times at the Yellow Sea. A region hit by red tide most frequently was Gyeongsang-do Province (over 80 times), which borders on both the South Sea and the East Sea. HABs written in the annals follow two distinctive occurrence patterns. The first pattern shows red tide started at Gangwon-do Province in March, spread north to Hamgyeongnam-do Province in April, and moved further north to Hamgyeongbuk-do Province in May and June. On the other hand, the second pattern shows red tide occurred in Gyeongsangnam-do Province in August and then expanded north to Gyeongsangbuk-do Province in September. HABs generally happened from March to September, culminating in August. Paralytic shellfish poisoning incidents involving human deaths were reported in Jinhae, Geoje and Tongyeong, occurring February to June. Fish mortality increased throughout Gyeongsang-do Province from July to September. HABs occurred on an extensive scale from 1394 to 1451 and again from 1654 to 1706. HABs also occurred on a lesser scale from 1493 to 1534 and again from 1588 to 1609. In general, vast HABs occurred in odd years (1399, 1403, 1413 and 1681).

• Korean Journal of Remote Sensing
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• v.25 no.6
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• pp.475-486
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• 2009

Harmful algal blooms (HAB) caused by the dominant species Cochlodinium polykrikoides (C. polykrikoides) appear in the South Sea of Korea and are particularly present in summer and fall seasons. Environmental factors such as water temperature, weather conditions (air temperature, cloud cover, sunshine, precipitation and wind) influence on the initiation and subsequent development of HAB. The purpose of this research was to study spatial and temporal variations of HAB in the Yeosu area using environmental (oceanic and meteorological) and satellite data. Chlorophyll-a concentrations were calculated using Sea-viewing Wide Field-of-view Sensor (SeaWiFS) images by an Ocean Chlorophyll 4 (OC4) algorithm, and HAB were estimated using the Red tide index Chlorophyll Algorithm (RCA). We also used the surface velocity of sequential satellite images applying the Maximum Cross Correlation method to detect chlorophyll-a movement. The results showed that the water temperature during HAB occurrences in August 2002-2008 was $19.4-30.2^{\circ}C$. In terms of the frequency of the mean of cell density of C. polykrikoides, the cell density of the HAB found at low (<300 cells/ml), medium (300-1000 cells/ml), and high (>1000 cells/ml) levels were 27.01%, 37.44%, and 35.55%, respectively. Meteorological data for 2002-2008 showed that the mean air temperature, precipitation, wind speed and direction, and sunshine duration were $22.39^{\circ}C$, 6.54 mm/day, 3.98 m/s (southwesterly), and 1-11.7 h, respectively. Our results suggest that HAB events in the Yeosu area can be triggered and extended by heavy precipitation and massive movement of HAB from the East China Sea. Satellite images data from July to October 2002-2006 showed that the OC4 algorithm generally estimated high chlorophyll-a concentration ($2-20\;mg/m^3$) throughout the coastal area, whereas the RCA estimated concentrations at $2-10\;mg/m^3$. The surface velocity of chlorophyll-a movement from sequential satellite images revealed the same patterns in the direction of the Tsushima Warm Current.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.627-633
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• 2019

Rapid and accurate identification of marine microalgae causing harmful algal blooms (HABs) is a crucial tool for predicting and managing HABs. We previously developed a nuclease protection assay sandwich hybridization (NPA-SH) method for the in situ detection of blooming microalgae Cochlodinium polykrikoides. In this study, we improved the applicability of the NPA-SH method for the detection of C. polykrikoides by simplifying the reaction step. For this purpose, invertase (INV) was conjugated to the signal probe instead of using fluorescence, and sucrose was used as a reactant to induce a color reaction. The INV-signal probe conjugation was confirmed by SDS-PAGE and epifluoromicroscopy. The treatment time and appropriate amounts of the probe and sucrose that optimized the reaction were determined. As a result, the developed INV-SH reduced the treatment time in the field compared with NPA-SH, and also enabled the use of a relatively small volume and low-priced personal glucose meter, as well as an absorbance meter. INV-SH is the first C. polykrikoides species identification technology to which INV has been applied and could be an improved field technique.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.1
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• pp.9-16
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• 2019

The algal blooms in stagnant streams and lakes have caused many problems. Excessive algae leads to disturbance of ecosystem and overload of water treatment processes. Therefore, phosphorus(P), source of algal blooms, should be controlled. In this study, a filtration trench has been developed to convert dissolved phosphorus into hydroxyapatite(HAP) so that it could be crystallized on the surface of 'phosphorus removal granular material'; and residual particulate phosphorus could be removed by additional precipitation and filtration. The front and rear parts of filtration trench consisted of 'phosphorus removal granular material contact bed' and 'limestone filtration bed', respectively. As a result of the column test using phosphorus removal granular material and limestone serially, $PO_4-P$ was removed more than 90% when EBCT(empty bed contact time) of the contact bed was over 20 minutes; and T-P represented 60% of removal efficiency when total EBCT was over 1.5 hours. The results of column tests to figure out the sedimentation characteristics showed that more than 90% of particulate phosphorus could be removed within 24 hours. It was necessary to optimize the filtration part in order to increase removal efficiency of T-P additionally. Also, it was confirmed through the simulation of Visual MINTEQ that most of particulate phosphorus in the column tests is the form of HAP. Based on the results of the study, it could be suggested that the design parameters are over 0.5 hour of EBCT for phosphorus removal granular material contact bed and over 1.5 hours of EBCT for limestone filtration bed.

• Korean Journal of Environmental Biology
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• v.37 no.1
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• pp.48-59
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• 2019

This study analyzed the water quality characteristics and developed empirical models prior to and after the construction of Baekje Weir, in the Geum River watershed between 2004-2017. The comparative evaluation of the surface water chemistry before and after the four major river projects on the weirs indicated that total phosphorus (TP), based on annual data, rapidly decrease after the construction of the weir while the total nitrogen(TN) decreased. Conversely, chlorophyll-a (CHL) concentration, which is a good indicator of primary productivity, increased after the construction of the weir together with an increase in specific conductivity. Simply put, the construction of the weir led to the decrease in concentrations of N and P due to the increased water residence time (WRT), whereas the CHL :TP ratio greatly increased in magnitude. The regression analysis of the empirical model indicated that CHL had no significant relation (r=0.068, p=0.6102, n=58) with TP before the weir construction, but had a relation with TP after the weir construction (r=0.286, p<0.05, n=56). Therefore, such conditions resulted in an increase in primary productivity on a given unit of phosphorus, resulting in frequent algal blooms. In contrast, seasonal suspended solids (SS) and TP increased during the monsoon period, compared to the pre-monsoon, thereby showing positive correlations (r>0.40, p<0.01, n=163) with precipitation. If the government consistently discharges water from the weir, the phosphorus concentration will be increased due to its reversion to a lotic waterbody from a lentic waterbody hereby reducing algal blooms in the future.

• Journal of Environmental Impact Assessment
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• v.32 no.5
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• pp.291-304
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• 2023

Harmful algal blooms (HABs) have become an increasing concern in terms of human health risks as well as aesthetic impairment due to their toxicity. The reduction of water pollutants, especially nutrients from non-point sources in a reservoir watershed, is fundamental for HABs prevention. We investigated the pollutant removal efficiencies of a constructed wetland to evaluate its feasibility as a method for controlling non-point sources located in the Annaecheon stream within the Daecheong Reservoir watershed. The overall removal efficiencies of pollutants were as follows: BOD 14.3%, COD 17.9%, SS 50.0%, T-N 19.0%, and T-P 35.4%. These results indicate that constructed wetlands are effective in controlling pollutants from non-point sources. The seasonal variation in removal efficiency depended on the specific pollutants. The removal efficiencies of BOD, COD, and T-N were stable throughout the year, except during winter, which might have been influenced by lower microorganism activity. In contrast, T-P showed a consistent removal efficiency even during the winter season, suggesting that the wetland can reduce external phosphorus loading to the reservoir. Regarding the effects of pollutant loadings on removal efficiency, the effluent concentrations of all pollutants were significantly decreased compared to those in the influent in case of middle and high loadings. This demonstrates that constructed wetlands can handle high pollutant loads, including the initial runoff during rainfall, to prevent reservoir eutrophication. Despite the various strengths of wetland water purification, there are limitations as passive treatment. Therefore, more case studies should be conducted to suggest optimum operational conditions for constructed wetlands, taking into consideration reservoir-specific characteristics.

• Korean Journal of Environmental Biology
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• v.41 no.4
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• pp.370-385
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• 2023

Cyanobacterial harmful algal blooms (Cyano-HABs) are an international environmental problem that negatively affects the ecosystem as well as the safety of water resources by discharging cyanotoxins. In particular, the discharge of microcystins (MCs), a highly toxic substance, has been studied most actively, and various water treatment methods have been proposed for this purpose. In this paper, we reviewed adsorption technology, which is recognized as the most feasible, economical, and efficient method among suggested treatment methods for removing MCs. Activated carbons (AC) are widely used adsorbents for MCs removal, and excellent MCs adsorption performance has been reported. Research on alternative adsorption materials for AC such as biochar and biosorbents has been conducted, however, their performance was lower compared to activated carbon. The impacts of adsorbent properties(characteristics of pore surface chemistry) and environmental factors (solution pH, temperature, natural organic matter, and ionic strength) on the MCs adsorption performance were also discussed. In addition, toward effective control of MCs, the possibility of the direct removal of harmful cyanobacteria as well as the removal of dissolved MCs using adsorption strategy was examined. However, to fully utilize the adsorption for the removal of MCs, the application and optimization under actual environmental conditions are still required, thereby meeting the environmental and economic standards. From this study, crucial insights could be provided for the development and selection of effective adsorbent and subsequent adsorption processes for the removal of MCs from water resources.

• Journal of fish pathology
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• v.16 no.3
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• pp.193-201
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• 2003

Mastoparan B (MPB), an antimicrobial cationic peptide isolated from the venom of the hornet Vespa basalis, is a basic amphipathic α-helical peptide composed of fourteen amino acid residues. In this study, we have investigated the algicidal effect of MPB against harmful algae blooms (HABs) casative Alexandrium tamarense, Chattonella marina, Cochlodinium polykrikoides and Gymnodinium catenatum. The algicidal effect of MPB showed in the concentration of 31.3 $\mu{g}$/mL to 500 $\mu{g}$/mL against 4 HAB species and observed cell lysis or cell ecdysis by microscopy. MPB reacted more sensitive to C. marina and C. polykrikoides than A. tamarense and G. catenatum. The algicidal study of MPB against HABs will provides much insight into development of new algicidal substances.

• Fisheries and Aquatic Sciences
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• v.7 no.3
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• pp.148-162
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• 2004

The monitoring activities at the National Fisheries Research and Development Institute (NFRDI) in Korea have been extended to include all the coastal waters of Korea after the outbreak of Cochlodinium polykrikoides blooms in 1995. We used several alternative methods including climatological analysis, spectral and optical methods which may offer potential detection of the major species of red tide in Korean waters. In the climatological analysis, NOAA, SeaWiFS, OCM satellite data was chosen using the known C. polykrikoides red tide bloom data and the area was mapped by helicopter reconnaissance and ground observation. The relationship between the distribution of sea surface temperature to C. polykrikoides bloom areas was studied. The anomalies of SeaWiFS chlorophyll a imageries against the imageries of non-occurring red tide for August, 2001 showed where the C. polykrikoides occurred. The anomalies of chlorophyll a concentrations from the satellite data during red tide outbreaks showed a similar distribution of C. polykrikoides in the red tide in August, 2001. The distribution between differences in sea surface temperatures during the day and at night also showed a possibility for red tide detection. We used a corrected vegetation index (CVI) to detect floating vegetation and submerged vegetation containing algal blooms. The results of from the optical absorption of C. polykrikoides in the ultraviolet band (340 nm) showed that if we use the optical characteristics from each red tide, we will be able to establish the feasibility of red tide detection.