• Korean Journal of Ecology and Environment
• /
• v.38 no.2 s.112
• /
• pp.237-248
• /
• 2005

To determine the content of hazard microcystin (MC) in Han River system and Ecological Ponds in Seoul City and Kyunggi district, a most toxic derivative, microcystin-LR (MCLR) of 15 samples of 7 ponds, 4 rivers and 4 reservoirs during low precipitation and cold season in 2003 were analyzed by ELISA method. With the change of water temperature ($0.4\;{\sim}\;21.9^{\circ}C$), cyanobacteria including Microcystis aeruginosa dominated the cold phytoplankton community in small ecological ponds such as Kyungbokgung Kyunghyaeru (KBP), Seokchon reservoir (SCR), Yangsoori Ryukgakji (YSS), having the long residence time. Contents of MCLR (the detection limit; $0.05\;{\mu}g\;L^{-1}$) were high in cyanobacteria-rich sites, especially, Microcystis aeruginosa. Total MCLR, cell extracted type plus dissolved type, were $1.39\;{\mu}g\;L^{-1}$ in KBP, $0.55\;{\mu}g\;L^{-1}$ in SCR and $0.59\;{\mu}g\;L^{-1}$ in YSS, in the first sampling having a high temperature (>$20^{\circ}C$), while some detected only in YSS during the cold season. As expected, the MCLR content was correlated with Microcystis aeruginosa (r = 0.526 for cell extracted type, r = 0.433 for dissolved type). Therefore, low concentration of MCLR detected in small ponds and Han river system in Seoul metropolitan city and Kyunggi district, maybe hardly affect human recreation activity, especially the drinking water supply.

• Toxicological Research
• /
• v.22 no.4
• /
• pp.375-380
• /
• 2006

Microcystin-LR (MC-LR) is a cyanobacterial hepatotoxin mainly produced by Microcystis aeruginosa. The current study examined the effects of a single intraperitoneal dose of MC-LR in rats. Female Sprague-Dawley rats were intraperitoneally injected with MC-LR ($100{\mu}g/kg$ body weight) and they were sacrificed at 0, 20, 40, 80, 160 min, or 12 h after injection. Clinically, animals showed lethargy and had ruffled hair beginning at 40 min post injection. In the gross findings, liver was enlarged and its color was changed into dark red beginning at 40 min post injection. Microscopically, dissociation of centrilobular hepatocytes and hemorrhage was observed in the hepatic central legions and such pathological changes were then extended to the portal regions of liver by time course manner. Interestingly at 80 min after MC-LR injection, the entrapped eosinophilic materials that may be necrotic fragments of dissociated hepatocytes were found in the capillaries of lung and renal glomerulus. Ultrastructurally, microvilli of the hepatocytes were disrupted or lost at all time points. Furthermore, the Disse space and gap junctions were widened beginning at 40 min post injection. These results suggest that liver is the major target organ of MC-LR and isolated hepatocytes by the effects of such hepatotoxin may secondarily reduce the physiological function of lung and kidney.

• Journal of Environmental Health Sciences
• /
• v.29 no.1
• /
• pp.74-83
• /
• 2003

Microcystin, stable compounds with circular heptapeptides, is presented inside cyanobacterial cell. So far, over 30 types have been known to exist and microcystin-LR, RR among them are the most potent toxin compound. By this reason, a strong oxidant, ozone was used in this study to remove the microcystins produced by cyanobacteria. Removal efficiency of microcystin at M water treatment plant was also evaluated. Microcystin concentration was determined by protein phosphatase inhibition assay. The results showed that dissolved microcystin in raw water detected in the range of 0.011-0.028 ㎍ Microcystin-RR equivalent/l. Above 98% of microcystin was removed through overall treatment system. Therefore, the water treatability of M treatment plant seemed to be excellent. Removal efficiency of microcystin according to unit process varied as characteristics of raw water such as DOC, UV/sub 254/ and turbidity. Removal efficiency of microcystin by ozonation was investigated in laboratory according to contact time and ozone dose. Dissolved microcystin was increased by twice fold according to ozone contact time, but increased by fifth fold according to ozone dose. So, changing of ozone dose more affected microcystin release than changing of ozone contact time. Behavior of microcystin by ozonation was similar to that of DOC, and residual ozone concentration gave influence to removal ratio of microcystin. In conclusion, single ozone treatment wasn't effective on microcystin removal in case of water containing a lot of cells. Therefore, it's more effective to use ozonation process after the removal of cyanobacterial cells in advance.

• Membrane and Water Treatment
• /
• v.10 no.6
• /
• pp.405-415
• /
• 2019

Microcystins (MCs) are toxins produced by cyanobacteria causing a major environmental threat to water resources worldwide. Although several MCs have been reported in previous studies, microcystin-LR (m-LR) has been extensively studied as it is highly toxic. Among the several techniques employed for the removal of this toxin, adsorption with AC has been extensively studied. AC has gained wide attention as an effective adsorbent of m-LR due to its ubiquity, high sorption capacity, cost effectiveness and renewability. In this review, the adsorption of m-LR onto AC was evaluated using the information available in existing scientific literature. The effects of the pore volume and surface chemistry of AC on the adsorption of m-LR considering the structural and chemical properties of ACs were also discussed. Furthermore, we identified the parameters that influence adsorption, including natural organic matter (NOM), pH, and ionic strength during the m-LR adsorption process. The effect of these parameters on MCs adsorption onto AC from previous studied is compiled and highlighted. This review may provide new insights into future activated carbon-m-LR adsorption research, and broaden its application prospects.

• Korean Journal of Ecology and Environment
• /
• v.38 no.2 s.112
• /
• pp.261-270
• /
• 2005

Biological control agents (BCA; algicidal bacterium Xantobacter autotrophycus) plus casitone media, strongly changed physicochemical variables, standing crops of phytoplankton and microcystin-LR phytoplankton in 100-L mesocosm constructed in a small hexagonal pond (3.5 m ${\times}$ 5 m). No M. aeruginosa showed by 8 days, and 60% of total standing crops of phytoplanktons were decreased by the BCA treatment. BCA treatment also induced a strong decline of cellular extracted microcystin-LR (MCLR) and a remarkable increase of dissolved MCLR with the decrement in standing crops of cyanobacteria. In addition, BCA strongly increased all nutrients, but new outbreak of phytoplanktons hardly showed in the experimental mesocosm. The field application of BCA to controling the cyanobacterial bloom in large lakes and reservoirs is not relevant due to high concentration of nutrients and toxins. Thus, a further study is needed to diminish the adverse effects after BCA treatment for water quality preservation.

• Environmental Analysis Health and Toxicology
• /
• v.18 no.3
• /
• pp.209-217
• /
• 2003

To investigate the effects of low dosed microcystin -LR (MCLR) on the initial stage of subacute hepatotoxicity in vivo, male Sprague-Dawley rats after weanling were divided in four groups. The orally treated group (OG) was administered orally by 1 $\mu\textrm{g}$/kg B.W. at an interval of three days. The free group (FG) has taken the drinking water including 1 $\mu\textrm{g}$/L freely and the control group (CC) was only treated with 0.9％ saline solution All groups were treated for a period of 3 weeks. There was a significant correlation in body growth rate between OG and FC and especially, a deterioration of the growth of spleen was observed in the FG after 5 days. The protein levels were also decreased in OG and FG after 9 days. Level of total fat was increased to the 9th day but again decreased up to the initial level. High hemolysis of the isolated erythrocytes occurred only in OG. Activities of ${\gamma}$-G7 of 0G and FG were higher twice-fold than CG, but the values of OG were already higher at the first treatment day. No significant change in aspartate aminotransferase (AST) activity was shown in all groups, but the activity of alanine aminotransferase (ALT) was slightly increased at the beginning state. There were much similarities in the results of OG and FG. except the growth inhibition of spleen in FG. It may be concluded that long -term effects of the low doses of mycrocystins in animals including human being can lead to serious health problems, especially to liver and spleen.

• Korean Journal of Ecology and Environment
• /
• v.44 no.4
• /
• pp.347-357
• /
• 2011

We examined two reservoirs (Inkyung res. and Joongang res.) and two streams (Kyungan str. and Jecheon str.), all of which were eutrophic, during the 2010 warm season, to evaluate the water quality improvement activity (WQIA) of plant-mineral composite (PMC), which was previously developed to control suspended solids, including cyanobacterial bloom (Kim et al., 2010). We simultaneously measured both solid (S-MCLR) and dissolved microcystin-LR (D-MCLR), before and after PMC treatment, in the Joongang reservoir. Taking water body size and volume into account, we conducted the whole-scale experiment in the Inkyung reservoir, and mesocosm-scale experiments in the other three systems. The WQIAs of PMC were found to be comparatively high in SS (70~81%), TP (75~91%), BOD (65~91%), Chl-a (88~98%), phytoplankton (84~92%) and zooplankton (68~88%), except for the Kyungan stream, which was below 45% in all parameters. After PMC treatment, the concentrations of both SMCLR (47%) and D-MCLR (96%) decreased within two days, suggesting a mitigation possibility of hazardous chemicals such as agrochemicals and endocrine disrupters in the aquatic ecosystem. Our results collectively indicate that PMC is a useful agent to control suspended solids, including nuisance cyanobacterial bloom and their exudates, in an undisturbed water system with a long residence time.

• Applied Chemistry for Engineering
• /
• v.24 no.5
• /
• pp.518-524
• /
• 2013

This study investigated the degradation of taste-and-odor compounds and toxins using dielectric barrier discharge plasma. The degradation of taste-and-odor compounds was conducted on geosmin and 2-methyl isoborneol (2-MIB), and the toxins investigated were microcystin-LR (MC-LR), microcystin-RR (MC-RR), microcystin-YR (MC-YR) and anatoxin-a. Largely depending on the type of gas fed to the plasma reactor, the degradation efficiencies of the taste-and-odor compounds decreased in order of oxygen (100%) > dry air (96%) > nitrogen (5%) for geosmin and in order of oxygen (100%) > dry air (94%) > nitrogen (2%) for 2-MIB on the basis of 150 s reaction time. This result suggests that the oxidative reactive species generated during plasma treatment, especially long-lived ozone, are mainly responsible for the degradation of these compounds. When using oxygen as the feed gas, geosmin and 2-MIB were totally degraded within 150 s, microcystins within 10 s, and anatoxin-a within 30 s. It was found that the taste-and-odor compounds and toxins were degraded more rapidly in real lake water than in distilled water.

• Proceedings of the Microbiological Society of Korea Conference
• /
• 2001.11a
• /
• pp.113-120
• /
• 2001

The production of microcystins from Microcystis aeruginosa was investigated in a P-limited continuous culture and a batch culture. The microcystin content of M aeruginosa was higher at a lower $\mu$, whereas the microcystin (MC)-producing rate was linearly proportional to $\mu$. The ratios of the MC-producing rate to the C-fixation rate were higher at a lower $\mu$. Consequently, increases in the microcystin content per dry weight along with the production of the more toxic form, MC-LR, were both observed under more P-limited conditions. The microcystin content of M. aeruginosa exhibited a high correlation with the total N content regardless of N-fixed or P-fixed culture. The microcystin concentration was investigated from spring to autumn in 1999 in the Daechung Reservoir, Korea. The dominant species in the algal blooming season was Microcystis. When the microcystin concentration exceeded about 100 ng $1^{-1}$ the ratio of particulate to dissolved total nitrogen (TN) or total phosphorus (TP) interestingly converged at a value of 0.6. The microcystin concentration was lower than 50 ng $1^{-1}$ at a particulate N:P ratio below 8, whereas the microcystin concentration varied quite substantially from 50 ng $1^{-1}$ to 250 ng $1^{-1}$ at a particulate N:P ratio> 8.

• Proceedings of the Korean Society of Fisheries Technology Conference
• /
• 1996.06a
• /
• pp.281-282
• /
• 1996